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  1. #401
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by oldranger View Post
    Note: their Gravity Rims are very popular amongst the riders in the Southeast. They have a 28.5mm internal width and in the 26" diameter the rim weighs 530g. I just can't afford a set at $1,200-$1,400.

    So...I have contacted them and will see if I can get some time with one of their folks to understand how they came up with 28.5 inner width. On their website they write: "The added traction and support our 28.5mm internal width provides is an incredible upgrade from the industry standard 21mm."

    26\" Gravity
    You are correct! I should have clarified that they are not yet convinced on the wide carbon rims.
    Function in disaster, finish in style.

  2. #402
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    Belive. Live. It's the mtb dream. It's finally here. Big rubber. Wide rims. Tubeless.
    On my 6.5" big boy bike. And my steel SS. And my trusty road bike.
    Volume. Lower/less tread. Bigger footprint. Lower psi.
    I run pacenti tl28 and dl31. Great rims. Narrow by wide standards. But much wider than the pinner rims of the late 80's 90's. A noticeable difference!

  3. #403
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    Pacenti

    Pacenti; that was a new one for me. Never heard of that company but they seem interesting. Nice MSRP at $80 - $90 per rim.

    From their website:
    The Pacenti DL31 rim was orignially designed as an Enduro rim, but has proven much tougher than its weight might suggest. For the last 2 seasons the DL31 has been proven on the toughest DH tracks in Europe under several Pro teams; including winning the 2013 Scottish National DH title under Joe Connell. The DL31 has a tubeless friendly design, welded construction and stainless steel eyelets. The DL31 is a wide, light rim designed for hard core trail riding, Enduro racing and the most extreme levels of DH abuse.

    DL31 Specifications:

    * Size: ISO 559 - 26"
    * Width: 31.0mm
    * Inner bead width: 26mm
    * Section Height: 20mm
    * ERD: 538mm
    * Weight: 522g
    * Welded Construction
    Attached Images Attached Images   

  4. #404
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    this picture sums up why I don't want wide rims. confirms my suspicions and riding experience that these are good for people who like to ride straight up and down, and don't lean. just like too wide of a motorcycle tire on a street bike makes the steering flat, vague, and lazy... until tire companies come up with something, I'll pass
    Attached Thumbnails Attached Thumbnails Wide Rims?  Don't believe the hype...-ibis-741-review-2470-780x520.jpg  

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  5. #405
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    i'm guessing wide rim on the left? i feel like anything over 27mm is too much, then it blocks the tires and you can't lean the bike over.

  6. #406
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    Quote Originally Posted by Yody View Post
    this picture sums up why I don't want wide rims. confirms my suspicions and riding experience that these are good for people who like to ride straight up and down, and don't lean. just like too wide of a motorcycle tire on a street bike makes the steering flat, vague, and lazy... until tire companies come up with something, I'll pass
    Is there a shot looking at the profile of the tire, the curvature of the tread face?

  7. #407
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    Quote Originally Posted by Yody View Post
    this picture sums up why I don't want wide rims.
    (1) You should not repost copyrighted images from one site on another. That image comes from this article.

    (2) That image is suspicious. The rim on the left is (supposedly) 41mm wide and has a 58mm wide tire on it, yet it appears that we see the rim outside the sidewall. Whatever the white-ish lines on either side are, they are not the (Ibis) rim.

    This picture tells us nothing other than that the tread doesn't get wider with wider rims (as some believe).

    The article reads like a forum post, but here's an interesting quote:

    "...we did experience some issues when it came to tyre choice. The tyres that perform best with these rims are those with rounded profiles, Maxxis Minions DHF, Schwalbe Hans Dampfs, and Maxxis Shorty’s all performed very well. However tyres with defined shoulder knobs or very square edges performed less so, with the breakaway point being moved to a shallower angle of lean and a resultant highly unpredictable handling. ..."

    So the tire in the picture is one that is claimed to work well, as does the Minion DHF. Curious considering the comments here. As for other tires working less well, duh. That has been true since the dawn of time.

    Find evidence that wide rims make all tires perform poorly and you might have something.

  8. #408
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    Quote Originally Posted by craigsj View Post
    (2) That image is suspicious. The rim on the left is (supposedly) 41mm wide and has a 58mm wide tire on it, yet it appears that we see the rim outside the sidewall. Whatever the white-ish lines on either side are, they are not the (Ibis) rim.
    Suspicious?

    The white-ish lines are part of the sidewall of the tire. Look at the next image down. See the sidewall there, with the cross-hatched pattern? That's the reinforced part of the carcass that is intended to protect against cuts and give stability.

    It's not visible in the pic on the 23mm rim because it's actually on the sidewall. The 35mm rim is stretching the tire profile enough that the sidewall is much nearer to ground.

  9. #409
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    The Pacenti rims were a treat to build up. I love that they have eyelets. The tubeless bead is excellent . With tires snapping into the seat reassuringly with a commpressor. And no obnoxious graphics.

  10. #410
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    Another relevant comment from the article/review of those wide Ibis rims:

    "Riding in Scotland we could not find any mud tyres that suited the wheels, most common spikes have a narrow tread profile and look like a Mohawk on the burly Ibis rims. "

    DH racers should really have a set mud tires. So if you go Ibis wide, be prepared to have another wheel set to support your wet conditions racing. Based on your mud tire of choice, it is possible you will have problems getting that tire to mount and give you the shape you need. I can't imagine seeing my Continental Mud Kings mounted up on these.

  11. #411
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    I've ridden the derbys with minions, same thing, outside knobs point upwards, I don't like the feeling when leaning over far, when you expect the tire to start pushing and drift it just kinda rolls over the knobs and just feels like its gonna tuck, instead of holding on and drifting. That picture shows exactly what I thought was happening. I'm not here to try and win the mtbr online argument. I'm just relaying my experience and opinion. Buy whatever you want I don't give a crap.
    friends don't let friends Fred

  12. #412
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    My buddy has those Pacenti's, they are very light, and soft. Dent very easily
    friends don't let friends Fred

  13. #413
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    With big tires , I have not dented these. I use 2.4 chunkey monkey on front and smorgashbord on the rear. 18 and 20 psi . Tubeless. On a full rigid SS.

  14. #414
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    Lol, Shredman says I'm clueless on my reputation sheet. LOL socal Fred has some nerve, I'd ride circles around you with your fancy shiny fred bikes.
    friends don't let friends Fred

  15. #415
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    Shredman neg repped me as well. He probably went through neg repping anyone that didn't bow down and pay homage to wide rims... because obviously, intelligent discourse should be eliminated. One opinion to rule them all!

  16. #416
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    I got a response from Pacenti on a message I sent them. Note upfront that Pacenti DL 31 rims have a 26mm inner width and therefore are not considered 'wide' in the context of this discussion.

    I have an excellent first impression of this company. Kirk Pacenti (father of the 650b tire diameter for MTB) has the kind of resume we need contributing to this discussion. I haven't asked his permission to quote him, but I will paraphrase a couple things from his very prompt, thorough response to my question. I asked him: "Hi, Do you offer 'wide' rims for DH use? I hear that today's 'wide' is more like 30mm inner width. But I see you've designed yours differently. I'm interested in your thoughts on the 26mm inner width and why that is best."

    Key points from his response:
    1) Once you get over 26-27mm inner width, the tire starts to get very square and doesn't roll over in corners and turns as easily as it should
    2) He designed the P35 and found the bike had so much traction you had to change your riding style. It was nearly impossible to break loose when you wanted them to.
    3) He prefers a slightly narrower DH rim for real racing
    4) They have pro DH teams racing the DL31

    I think the DH riders/racers monitoring this thread will well understand the second point I paraphrased from Mr. Pacenti. Yody has already comments on this.

    Yody - I can imagine those Pacenti Rims do dent easily. AT 530 grams they would be too light for me - I make mistakes and dent my relatively soft FR600s that weigh in at 600 grams. That said - the DL31 might be a really good race day option and they have a great price point.

  17. #417
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    Quote Originally Posted by Yody View Post
    My buddy has those Pacenti's, they are very light, and soft. Dent very easily
    They're about the same as Flow in the dent dept imo. DL31 little easier to fix the half dents, have you compared the newer offerings from Alex or DT?
    video=youtube;][/video]...

  18. #418
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    I race my pacenti rims. I've also dented every rim I've used sooner or later. My crank brothers iodine wheels are the worst softest rims ever.
    I'm not DH ing though . Only Xc . So stuff lasts longer

  19. #419
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    Wide Rims? Don't believe the hype...

    I've found the higher volume tires like some of the Schwalbes and Maxxis still give me a slightly round profile on the Fatties. I used to really like the Nevegal in 2.5 on my 36mm OD wide 26" rims. I don't have any issues with cornering using Hans Damfs or Nobby Nics on the Fatties, the 2.4 Ardents would also work well. The choice of tires to match the rim width is very important to the overall performance of the combo.
    Function in disaster, finish in style.

  20. #420
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    I'm a hype-believer. I ordered a set of Roval Traverse Fattie SL 29er wheels. Under 1600g with 30mm internal width and 6-degree hub engagement -- sounds pretty sweet to me.

  21. #421
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    i feel that for some, wide tires are useful, i feel that for some tires, like the DHF that a wide tire wouldn't block it out too much, i rode some Roval Traverse SL Fattie 650B 142+ wheels, on an Sworks Enduro, and i didn't find any faults in them on the ride, i cornered hard on flat ground, i didn't use many berms on the trail ride for the demo. i didn't think there was anything special about them though, they felt similar to my 23mm wheels, only lighter and stronger. i didn't look at the tires and see if they had an odd shape, but on the trail the felt fine. i didn't find any limitation in cornering, but it was only a 30-45 minute ride, and it was all together a new bike.

    It'd be cool to be able to throw on a pair of wide rims on my current bike, ride my favorite trails, and see if there is a noticeable difference. for free that is.

  22. #422
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    Wider rims and large casing tires, make rigid SS riding quite nice. For this application I welcome the trend. But this doesn't mean I'll be swapping out the wheels on the other bikes .

  23. #423
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    Quote Originally Posted by ColinL View Post
    Suspicious?
    Yeah, suspicious. Of course the lines have to be part of the tire. I've never produced such a thing on the images I've taken of that same perspective. It's incumbent on the authors and photographers to produce information that informs, not misleads. The other 99 shots out of 100 would not look like that IMO.

    Not sure what that photograph tells anyone once you factor out how peculiar one side looks. It's meaningless.

    Quote Originally Posted by ColinL View Post
    Shredman neg repped me as well. He probably went through neg repping anyone that didn't bow down and pay homage to wide rims... because obviously, intelligent discourse should be eliminated. One opinion to rule them all!
    Intelligent discourse?

    The rep system is worthless and ineffective as is complaining about it in-thread. Simply don't participate.

    Even more embarrassing is people who attach insults (friends don't let friends Fred) in their footer. It's clear who people are.

  24. #424
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    Quote Originally Posted by craigsj View Post
    Yeah, suspicious. Of course the lines have to be part of the tire. I've never produced such a thing on the images I've taken of that same perspective. It's incumbent on the authors and photographers to produce information that informs, not misleads. The other 99 shots out of 100 would not look like that IMO.

    Not sure what that photograph tells anyone once you factor out how peculiar one side looks. It's meaningless.
    Actually, when I read your post with 'suspicious' I thought it was an interesting term to use because it seemed as if you believed the photo was taken with the tire on a different wheel. Not wrong, but suspicious. As in fake, or deceptive?

    It's not fake, it probably hasn't been photoshopped, and the article does contain several pieces of information (pictures and text) that clearly express the opinion that wide rims are not an improvement for some tires.

  25. #425
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    Here are my experiences...not DH. I live in Wisconsin so mostly XC and some AM/TR. I was on a set of skinny rims and 29x2.1s and hated them. Then I went BIG with a set of P35s and Conti Trail King 2.4s. Traction for miles, but I had to re-dish the rear wheel for FD clearance and they rubbed by noodly fork like crazy. Switched to 29x2.2 and fixed the rubbing issues. The tires measured almost 2.4 on the wide rims though. I then switched to a 23mm internal rim and the 2.2 tires now feel much better, but I have to run higher pressures and they slide around much more. All of my experiences follow what was paraphrased above about the P35 rim and changing riding style.

  26. #426
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    Quote Originally Posted by craigsj View Post
    Yeah, suspicious. Of course the lines have to be part of the tire. I've never produced such a thing on the images I've taken of that same perspective. It's incumbent on the authors and photographers to produce information that informs, not misleads. The other 99 shots out of 100 would not look like that IMO.

    Not sure what that photograph tells anyone once you factor out how peculiar one side looks. It's meaningless.


    Intelligent discourse?

    The rep system is worthless and ineffective as is complaining about it in-thread. Simply don't participate.

    Even more embarrassing is people who attach insults (friends don't let friends Fred) in their footer. It's clear who people are.
    I can call you herb instead of Fred if it makes you feel any better, lmao
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  27. #427
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    Quote Originally Posted by ColinL View Post
    Actually, when I read your post with 'suspicious' I thought it was an interesting term to use because it seemed as if you believed the photo was taken with the tire on a different wheel. Not wrong, but suspicious. As in fake, or deceptive?

    It's not fake, it probably hasn't been photoshopped, and the article does contain several pieces of information (pictures and text) that clearly express the opinion that wide rims are not an improvement for some tires.
    Yes as in fake or deceptive.

    The article did express an opinion clearly, one that seemed no more informed than many forum posts, but the article was not posted here, only a single picture that looked suspicious. There is no reason to believe that picture supports any narrative and the article itself claims that pictured tire works well with the wide rim.

  28. #428
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    Quote Originally Posted by Yody View Post
    I can call you herb instead of Fred if it makes you feel any better, lmao
    I would have to respect you in order to care what you called me.

  29. #429
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    Quote Originally Posted by craigsj View Post
    I would have to respect you in order to care what you called me.
    The feeling is mutual then, because i have zero respect for armchair quarterback engineers who can't ride for **** but love to argue online about specs and millimeters and lazer beams and convince themselves that they are right because they win the internet. I bet you ride by yourself all the time because nobody wants to hear your techno babble the whole ride, lmao
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  30. #430
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    Well this is fun guys. Sounds like it's time for some back to back to back to back testing. Unfortunately most of us don't have the coin to drop on multiple wheelsets to put through the wringer. If only there were "people" with "relationships" with these "companies" that could ride competing "products" and share something approaching objective "comparisons." We could of course decide how relevant those comparisons for each of us. Not sure a 120 pound woman at Vital is gonna get the wheel to flex like a Clyde. If you ride with a unique style, unique terrain, or just consider yourself too damn unique, it'll be up to you to compare directly.

    Let's start hammering on the editors/moderators of the MTBR, Pinkbike, Vital, and the Euro Mags to tackle this issue. I'm pretty damn impressed by the commitment demonstrated by John Schafer here at MTBR to compare POV cameras. Trying to run more than two wheels at once would unfortunately kick you out of the whole "bi-cycle" thing.

    Wide Rims?  Don't believe the hype...-go_pro.jpg

  31. #431
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    Not back to back, but one weekend I rode a DH trail in Santa Cruz (short loops) 5 times on a new Ibis Demo HD3 with Derbies and Minions. (I've been running minions on and off for more than a few years so I know the feel of them). Then went back a week or so later and rode it again multiple times on my 26" HD with Minion front and 28MM wide rims (23 internal)

    I definitely felt like the wider wheels/minions felt awesome until you get to the drift point, you know that feeling as you load up the tire into a decreasing turn, and as it gets tighter you go to load more and get the wheel to start pushing..... I didn't like the way it felt on the wide rims. Didn't give me confidence, it would just try and tuck the front end. As well the minion on rear felt like way too much tire and wouldn't break loose ever, didn't like that but thats kind of a different matter. Traction up and down was really good and the bike felt super planted. But really I want max performance where it really counts
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  32. #432
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    Quote Originally Posted by Yody View Post
    Not back to back, but one weekend I rode a DH trail in Santa Cruz (short loops) 5 times on a new Ibis Demo HD3 with Derbies and Minions. (I've been running minions on and off for more than a few years so I know the feel of them). Then went back a week or so later and rode it again multiple times on my 26" HD with Minion front and 28MM wide rims (23 internal)

    I definitely felt like the wider wheels/minions felt awesome until you get to the drift point, you know that feeling as you load up the tire into a decreasing turn, and as it gets tighter you go to load more and get the wheel to start pushing..... I didn't like the way it felt on the wide rims. Didn't give me confidence, it would just try and tuck the front end. As well the minion on rear felt like way too much tire and wouldn't break loose ever, didn't like that but thats kind of a different matter. Traction up and down was really good and the bike felt super planted. But really I want max performance where it really counts
    So it just sounds like it was a little different than you are used to... when at the same time comparing a different wheel size altogether (the HD3 is 650b, right?).
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  33. #433
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    Wide Rims? Don't believe the hype...

    I'm kind of thinking that the reasons you stated about drift and lean angle are why most of us with wider rims are finding lower air pressures with wide rims compared to narrower rims feel better on the handling side of things. I think the tires need more squash with the lower air pressure to allow more lean angle and the lower pressure also creates a bigger footprint.
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  34. #434
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    Wide Rims? Don't believe the hype...

    I have some I9 Enduros w/ Flow rims and the SL Fatties both currently mounted with 2.35 Nobby Nics. I'll try to take some photos this weekend and air them up to the to identical pressure before hand for comparison sakes. I'm still playing around with the fatties to find the ideal tire to use with them.
    Function in disaster, finish in style.

  35. #435
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    Quote Originally Posted by OriginalDonk View Post
    Let's start hammering on the editors/moderators of the MTBR, Pinkbike, Vital, and the Euro Mags to tackle this issue.
    Wide rims will evolve much like larger wheel sizes did, only more rapidly, and if you want to understand the market reaction, just read up on the 5 stages of grief. A fun exercise is to identify the stages of certain posters here.

    One things for sure, reviews by the people you mention won't tell us anything. Read what howell has to say instead. Tire designers actually work with this stuff. The market will accept wider rims and tires will evolve, just like they always have.

  36. #436
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    Quote Originally Posted by craigsj View Post
    Wide rims will evolve much like larger wheel sizes did, only more rapidly...Tire designers actually work with this stuff. The market will accept wider rims and tires will evolve, just like they always have.
    Has anyone found information that indicates tires are evolving for these wider rims?

    Craigsj, when do you think the tire manufacturers and Pro DH race teams will get caught up with the wide rims (> 28mm internal width) movement?

  37. #437
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    28 internal isn't even a new thing, I had those 4 years ago.
    I like to fart when I'm in front of you on a climb:skep:

  38. #438
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    A tire's contact patch under load in dynamic operation does not resemble its unloaded static image.

    When applying steering input, the tire contact patch lags behind the vertical centerline of the wheel (pneumatic trail), and deviates to the inboard side of a turn. This deviation is called slip angle. The greater the slip angle, the more understeer is introduced. Understeer is mostly derived from the tire's tendency to continue in its original direction in deference to steering input. There are other factors involved, but for simplicity sake I'm focusing on the tire & rim role. For the same size tire & air pressure, increasing rim width shortens the contact patch and increases its width, contact area remains unchanged. The shorter the contact patch, the shorter the lag behind the wheel's vertical centerline. Relatively widening the rim, widens leverage for the tire sidewall, which stabilizes the tire laterally, and reduces contact patch deviation inboard to a turn, resulting in reduced slip angle. low slip angle inhibits understeer characteristics. Some riders in this thread consider understeer (drifting, push) to be a positive attribute. I prefer steering response and bike direction to closely match steering input. I find an appropriate width rim to perform as intended; not hype.

  39. #439
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    Quote Originally Posted by oldranger View Post
    Has anyone found information that indicates tires are evolving for these wider rims?

    Craigsj, when do you think the tire manufacturers and Pro DH race teams will get caught up with the wide rims (> 28mm internal width) movement?
    Lol, just because a bunch of weekend warriors like a new product that makes them feel better, does not mean that everyone else is gonna get "caught up with the movement".
    friends don't let friends Fred

  40. #440
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    Quote Originally Posted by HillDancer View Post
    A tire's contact patch under load in dynamic operation does not resemble its unloaded static image.

    When applying steering input, the tire contact patch lags behind the vertical centerline of the wheel (pneumatic trail), and deviates to the inboard side of a turn. This deviation is called slip angle. The greater the slip angle, the more understeer is introduced. Understeer is mostly derived from the tire's tendency to continue in its original direction in deference to steering input. There are other factors involved, but for simplicity sake I'm focusing on the tire & rim role. For the same size tire & air pressure, increasing rim width shortens the contact patch and increases its width, contact area remains unchanged. The shorter the contact patch, the shorter the lag behind the wheel's vertical centerline. Relatively widening the rim, widens leverage for the tire sidewall, which stabilizes the tire laterally, and reduces contact patch deviation inboard to a turn, resulting in reduced slip angle. low slip angle inhibits understeer characteristics. Some riders in this thread consider understeer (drifting, push) to be a positive attribute. I prefer steering response and bike direction to closely match steering input. I find an appropriate width rim to perform as intended; not hype.
    Slip angle and steering! Haha. That could be a quote from various car handling books or forums.

    MTBs are not cars. Problem #1 with your assumption that they act the same is that bicycles are leaned into turns at speed. Problem #2 is that MTB tires are designed to lean and have tread on the shoulder that only gets traction when the tire is leaned.

    When you flatten the tread face of a MTB tire beyond what the tire designer intended, the shoulder knobs cannot be used as designed. Additionally, the profile of the tire is no longer as rounded, which supports the ability to transition smoothly from left, center and right of the tire.

    This was all said many times in this thread, but no one else came in here quoting Skip Barber...

  41. #441
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    Quote Originally Posted by Yody View Post
    Lol, just because a bunch of weekend warriors like a new product that makes them feel better, does not mean that everyone else is gonna get "caught up with the movement".
    Sounds like someone's afraid the bike daddy bought them isn't gonna be what the cool kids ride anymore. Lol.

  42. #442
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    Quote Originally Posted by ColinL View Post
    Slip angle and steering! Haha. That could be a quote from various car handling books or forums.
    Agreed, but the most basic reason this does not apply you've overlooked.

    A wider rim on MTB does not make the contact patch wider and shorter. MTB tires contact the ground through their tread and the tread doesn't widen just because the rim does. If the tire were a smoothie on a smooth surface then things would be different, knobs change things considerably.

    People should go back to post #378 in this thread and read the bhowell quote. There's a lot of solid information there that is commonly misunderstood.

  43. #443
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    Quote Originally Posted by craigsj View Post
    ...A wider rim on MTB does not make the contact patch wider and shorter...People should go back to post #378 in this thread and read the bhowell quote...
    Your reading comprehension is poor. Originally Posted by bholwell "As the internal width of the rim increases, the contact patch will become wider and shorter"

    A lugged bike wheel does not tip-toe through a corner.


    Quote Originally Posted by ColinL View Post
    ...no one else came in here quoting Skip Barber...
    Neither did I, those are my words.

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    Hilldancer and craigsj are probably the same person, trolls
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  45. #445
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    Quote Originally Posted by HillDancer View Post
    Your reading comprehension is poor. Originally Posted by bholwell "As the internal width of the rim increases, the contact patch will become wider and shorter"
    A full quote is called for here, not a butchered one to mislead others:

    "As the internal width of the rim increases, the contact patch will become wider and shorter (assuming the inflation pressure and load is kept constant.) However if the shoulder lugs are already in contact with the ground, the contact patch cannot grow wider; instead it becomes more squared off, and the pressure distribution within the contact patch changes."

    This is not a demonstration of my reading comprehension either. bhowell and I agree because we both understand how it works, not because I've paraphrased what he has said.

    Quote Originally Posted by HillDancer View Post
    A lugged bike wheel does not tip-toe through a corner.
    Congratulations on your deepity. You've shown that you're both an idiot and an a-hole.

  46. #446
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    Quote Originally Posted by craigsj View Post
    A full quote is called for here, not a butchered one to mislead others:

    "As the internal width of the rim increases, the contact patch will become wider and shorter (assuming the inflation pressure and load is kept constant.) However if the shoulder lugs are already in contact with the ground, the contact patch cannot grow wider; instead it becomes more squared off, and the pressure distribution within the contact patch changes."

    This is not a demonstration of my reading comprehension either. bhowell and I agree because we both understand how it works, not because I've paraphrased what he has said.
    Ok, I'm in the market for new wheels and am looking at wider rims. Mostly because I my pressures go lower without rim strikes but get too squirmy. So I have been following this thread with interest even though I would describe my riding as all mountain as opposed to downhill.

    I understand that the claim is that contact patch doesn't get wider and shorter (relative to narrower rims) if the shoulder lugs are in contact with the ground. Does this mean both left and right shoulder lugs? In other words wheel is vertical? Or does it mean if any shoulder lugs (wheel is tilted)? Does the reference to the contact patch not growing wider mean relative to narrower rimmed tires or mean growing wider under the load of the turn? Just trying to understand. thanks.
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    I'm sure Craig can explain it to you in small words. He's the smartest person on MTBR. Now if folks would just stop quoting his responses, my ignore function would work properly.

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    I'm no engineer, but in my opinion, the picture mattwright999 just posted should be considered marketing hype.

    "The tire folds and can even jump out of the rim".

    Really? Wow, there is so much bad information. This is why I still fall back to: show me a pro race DH team that is going with wide rims >28mm internal width. Or show me a tire manufacturer that is redesigning tires intended for wider rims.

    I was thinking about it again...the fact the Specialized DH Race team is using the DT Swiss EX471 for racing instead of the wider, heavier rims is yet another solid indicator of what is important. They could choose any rim they wanted from the DT lineup, and they don't choose the widest one.

  50. #450
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    Specialized DH team choice is interesting in light of their enduro team riding 30mm internal width rims this last year.
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  51. #451
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    Quote Originally Posted by oldranger View Post
    Really? Wow, there is so much bad information. This is why I still fall back to: show me a pro race DH team that is going with wide rims >28mm internal width. Or show me a tire manufacturer that is redesigning tires intended for wider rims.

    I was thinking about it again...the fact the Specialized DH Race team is using the DT Swiss EX471 for racing instead of the wider, heavier rims is yet another solid indicator of what is important. They could choose any rim they wanted from the DT lineup, and they don't choose the widest one.
    Funny that you mentioned Specialized, in theory at least, they have the capability to design their own tires to go with wider rims, should they choose to run them. Trek I'd think does as well since they run Bontrager, and both of them have the size, market clout, and vertical integration to go all in on wide rims & tires. For whatever reason, nether Trek nor Specialized has gotten on the wide rims & tires train yet.

    On the other hand it looks like the Ibis Enduro team will be on wide carbon wheels for the upcoming season. Guess we'll find out how well they work when Anne-Caroline Chausson & the rest of the team gets some races on them this year. If ACC cleans up this year then I we can say there might be something to them, if she and Tracy Moseley end up splitting the series again, I'd say it's inconclusive at best.

  52. #452
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    Quote Originally Posted by aerius View Post
    Funny that you mentioned Specialized, in theory at least, they have the capability to design their own tires to go with wider rims, should they choose to run them. Trek I'd think does as well since they run Bontrager, and both of them have the size, market clout, and vertical integration to go all in on wide rims & tires. For whatever reason, nether Trek nor Specialized has gotten on the wide rims & tires train yet.

    On the other hand it looks like the Ibis Enduro team will be on wide carbon wheels for the upcoming season. Guess we'll find out how well they work when Anne-Caroline Chausson & the rest of the team gets some races on them this year. If ACC cleans up this year then I we can say there might be something to them, if she and Tracy Moseley end up splitting the series again, I'd say it's inconclusive at best.
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  53. #453
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    Have you ever ridden a pro rider's bike? Most of them would be completely foreign to an average joe like me and, presumably, most MTBR users.

    Which is a roundabout way of saying I don't base any cycling parts decisions on what professional teams are running. But I still run skinny-ish rims, too, so what do I know.

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    Girl Fight!!

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    Wide Rims? Don't believe the hype...

    I'd say settle down a bit. We're only talking about wheels and rim width! Folks also need to ride all these wheels with wider rims before they make such strong statements for or against. I've got wheels with rim widths from 21-40mm and they all have a place in mountain biking. I'm not saying ditch your skinnier rims but I've also found that the wide rims have great purpose.

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  56. #456
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    Wide Rims? Don't believe the hype...

    Wow I hope I wasn't a buzz kill here!!😬
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  57. #457
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    Quote Originally Posted by manitou2200 View Post
    Wow I hope I wasn't a buzz kill here!!😬
    That's what happens here when rational thinking and reasoning are introduced!
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  58. #458
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by blcman View Post
    That's what happens here when rational thinking and reasoning are introduced!
    Haha! There was some very good discussion going on in this thread but also some butt hurt pissing matches which are never good!

    I hope all those carrying on here can engage in constructive discussion. I know the op was referencing downhill but most of it also applies to all mountain riding which is a much larger group of riders.
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  59. #459
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    I might have to see how my Conti Trail King 29 x 2.4 look on a 15mm internal vs the P35s.

  60. #460
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    Quote Originally Posted by mattwright999 View Post
    Name:  Syntace-mountain-bike-wheels-rim-profiles.jpg
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    I'm with old ranger on this one - the picture above is drawn and is typical of an ad agencies drawing - competing red and green ( good versus bad)is a dead giveaway it's for marketing purposes. It may or may not be accurate, but it's source is biased and designed to tell a story in favour of wide.

    That picture therefore is evidence for the "hype" posited at the start of the thread.

  61. #461
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    Quote Originally Posted by manitou2200 View Post
    I'd say settle down a bit. We're only talking about wheels and rim width! Folks also need to ride all these wheels with wider rims before they make such strong statements for or against. I've got wheels with rim widths from 21-40mm and they all have a place in mountain biking. I'm not saying ditch your skinnier rims but I've also found that the wide rims have great purpose.

    Girl fights are fun too though!!
    I get what you are are saying, but first hand experience isn't all it's cracked up to be. People will defend what they have bought till the ends of the earth, and especially if they seem to know a vendor. : D

    No idea how to test them empirically and reliably.

    I think I'm a moderate on this one - I've read all I can find, and have been swayed by the professional design engineers on the subject. I think places like pinkbike are far from neutral ( or thoughtful) - though to be fair, I've seen behind the scenes in public relations versus journalism, and regrettably the smarter people are driving the marketing and can pull the wool over the eyes of a journalist with remarkable ease.

    Anyway, I think there is an advantage to wider rims upto around 25mm

  62. #462
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    Quote Originally Posted by pharmaboy View Post
    I get what you are are saying, but first hand experience isn't all it's cracked up to be. People will defend what they have bought till the ends of the earth, and especially if they seem to know a vendor. : D

    No idea how to test them empirically and reliably.

    I think I'm a moderate on this one - I've read all I can find, and have been swayed by the professional design engineers on the subject. I think places like pinkbike are far from neutral ( or thoughtful) - though to be fair, I've seen behind the scenes in public relations versus journalism, and regrettably the smarter people are driving the marketing and can pull the wool over the eyes of a journalist with remarkable ease.

    Anyway, I think there is an advantage to wider rims upto around 25mm
    Why do you call the limit at 25mm? Is that due to current tire design? Or something inherent in the width of the rim itself? I am asking because I am in the market for some new wheels and am trying to decide between 25mm and 30mm. I am more of an AM rider than DH, but I push speed through some steep, fast, chunky, singletrack. I am also not a racer and am relatively new to MTB (1.5 years riding) so I am not sure that at my skill level I would necessarily be able to tell the difference, At the same time, I don't want to get something that is actually going to decrease performance, so I have been following (most) of this debate with interest.

    From what I can glean most of those favoring the not so wide rims (28mm and less?) do so because of the adverse affect on the tire profile that the wider rims have on high speed cornering performance. This seems to be an issue for people who are going DH speeds and happens because the tread closes up as the rim becomes wider changing the performance of the tire. Most find this change negative. A few positive, ay least when considering the ability to run lower pressures without tire squirm.

    I noticed that at EWS Whistler at least, and I think for the whole series, the Specialized riders were on the 30mm interior Traverse Fatties and were on standard Slaughter and Butchers. Specialized's data from the bikeradar review indicates that 30mm interior rims have around 18-20% less deflection than a 23mm int rim and they state that they think the sweet spot right now in terms of wheel weight vs rim width is 30mm.

    I guess I am wondering how application specific rim width is right now? Perhaps for those of us not going DH race speeds on the descents, a 30mm interior rim is perfectly fine, stabilizing the tire at lower PSI, allowing more traction through that PSI while avoiding squirm while at DH speeds the change in tire profile combined with the more aggressive lean angles is actually more detrimental to performance than any traction/rolling benefit gained while not cornering super aggressively.

    Just trying put together a summary overview of this thread for myself.
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  63. #463
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    More information from a late 2014 race on one of the most extreme downhill tracks ever conceived: Redbull Hardline.

    Red Bull Hardline Dan Atherton

    I put this in here so those readers that may not know how dramatically different Downhill racing is from XC or Enduro can get a glimpse of where the DH sport is heading. This is an extreme event for 10 of the top riders in the world.

    2.4 - 2.5 width tires and conventional, aluminum DH rims seem to be the prevalent choice at a venue where it seemed 'anything goes'. The winner was riding on Easton Havoc rims, and the track builders were riding narrow, cut mud spike tires in dry, loose conditions. (Conti Mud King 2.4)

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    i think 27mm is the limit. its wider, but not WIDE its been used by DT swiss for some time now, and on a 2.5 or 2.4 inch tire it'd still be perfectly useable for DH and FR. i think 25mm is good for any application.

    But idc too much. ride whatever you want to ride, you guys need to stop bickering. some people want to buy the $3,000 carbon wide rims, and others of us will settle with 1,100 dollar alloy rims that are just as strong, just as capable, and not as wide, but a little heavier.

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    You guys need to keep bickering. In fact kick some ass while you're at it!!

  66. #466
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    Quote Originally Posted by IPunchCholla View Post
    Why do you call the limit at 25mm? Is that due to current tire design? Or something inherent in the width of the rim itself? f.
    Yep, the 2 tyre designers on these forums talk about designed rim size and not moving too far away from that. Second, the manufacturers who have the ability and testing facilities aren't screaming off into 30mm widths. Advances in width have been incremental over the last couple of years, jumping straight up to 30 from 23 (current flows) seems a big leap of faith.

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    Wide Rims? Don't believe the hype...

    I can feel the added support of the wider 30mm rims of my Fatties on the high volume 2.35+ size tires. As compared to my I9 Enduro/ Flow 25mm wide rim wheels there isn't any loss in cornering or ability to lean the bike in the turns.

    I feel that for tires under 2.3"/ high volume casings type tires that the gains would not be there and for smaller casing tires it might be detrimental to the handling. I think it's very much tire size related and especially tire volume. Like comparing gen 1 High Roller 2.35 to a Hans Damf or 2.4 Ardent or 2.4 trail King. There is no comparison in casing volume or tread width, the HR while a good tire is no where near as big as the others.

    On the other hand install a Surley Knard 3.0 on a 24/26mm wide rim and see how that performs. It's not happening that's for sure!

    It's a matter of choice and matching tires and wheels. I get pro deals from pretty much all the manufactures so I'm able to try stuff out and see what I like. I sell off stuff I don't like and I'm not selling my SL Fatties. I'm also not selling my Flow rim Enduros either. I'll set them up for different conditions and riding types. I'm going to put heavier weight tires on my Enduros that I'll use when shuttling runs and use the lighter fat tires on the Fatties.

  68. #468
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    Quote Originally Posted by pharmaboy View Post
    Yep, the 2 tyre designers on these forums talk about designed rim size and not moving too far away from that. Second, the manufacturers who have the ability and testing facilities aren't screaming off into 30mm widths. Advances in width have been incremental over the last couple of years, jumping straight up to 30 from 23 (current flows) seems a big leap of faith.
    Advances in width haven't been incremental, they've been dramatic, and "jumping straight up" wouldn't be a "big leap of faith", it would be naive. The language you use suggests manufacturers are worried about going too far; that's not what's happening here.

    There's a whole lot more at play than just the objective facts of how a rim works yet these things are conveniently ignored by those who don't want their narratives spoiled. Designers could optimize for wider rims but they'd like a large market of wide rim riders to sell to first. We ride bicycles, not rims.

    If 80% of the market was 30+mm rims you can bet that tires would be designed to work well on them and people would laugh at narrow-rim riders. That's not a statement of superiority, it's just how things are. This is the case today with narrow rims and it has, until recently, been the case for juvenile wheel sizes. Progress isn't instantaneous.

    The fact is, racers (who drive a large portion of the cycling market) will not leave performance on the table once it's staring them in the face. The problem with wider rims is that they are making tires work better than intended and that actually causes problems in certain cases. Racing will adapt. New technologies are usually NOT greeted with optimized complimentary technologies out of the gate. It takes time.

  69. #469
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    Sorry, Craig, I haven't been clear. When I say incremental, I'm not including small niche manufacturers in particular over the near term, but the big guys who have moved from 19 then to 21 and out to 23 over the last 4 years or so.

    I agree we buy bikes and don't think manufacturers are being conservative because of worry, it's more likely simply engineer driven - there are plenty of smart people working in industrial design, frankly, a whole lot smarter and better trained than a few journalists that ride bikes.

    That after all is what the original "hype" question is what it's all about - lots of emotional words and unprovable concepts

  70. #470
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    Quote Originally Posted by pharmaboy View Post
    Sorry, Craig, I haven't been clear. When I say incremental, I'm not including small niche manufacturers in particular over the near term, but the big guys who have moved from 19 then to 21 and out to 23 over the last 4 years or so.
    Ah, yes that's true.

    I find it very disappointing how seldom advances come from larger manufacturers.

  71. #471
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    I'm really wondering if and when tire manufacturers are going to assume that there are going to be enough wide rim owners to buy wide rim optimized tires. Sounds like WTB may already be on that track given their open discussion on Pinkbike but I'm wondering if and when Maxxis and Schwalbe may go down that road.

    I always find Country-specific tax and duty situations to be really interesting. I'm seeing more and more 30+ internal rims used in the U.S. and Canada, presumably because they're easier to get over her with Ibis, Derby, NOX, etc. It seems like 90% of European and "Commonwealth" (Australia, New Zealand, South Africa, etc.) riders are rolling around on narrow Euro produced products given the tax and duty situation. They're just so much cheaper. Anybody can order Light Bicycle rims or bring some Derbies over but few seem to want to fight their way through customs and pay those duties. The wide rims available at lower costs in the U.S./Canada are at a large economic disadvantage in Europe.

    The U.S. and Canada are huge markets but I think a Euro wide rim champion (in addition to Syntace) may be needed before tire companies decide to invest in the effort to design wide-specific tires.

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    My LBS is lacing up a set of Derby's for me, going from Crest's the difference should be evident if it's tangible.

    I have high hopes, but I ride trails, not a dedicated downhiller. I leaned forward in my seat when the discussion started toward differences in rim width exhibiting attributes that suggest, as most things mountain bike, it can be either a benefit or a detriment depending on rider and intended use.

  73. #473
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    Quote Originally Posted by OriginalDonk View Post
    I'm really wondering if and when tire manufacturers are going to assume that there are going to be enough wide rim owners to buy wide rim optimized tires. Sounds like WTB may already be on that track given their open discussion on Pinkbike but I'm wondering if and when Maxxis and Schwalbe may go down that road.
    .
    Be careful with wtb. Their tyres are their own system and mate well with wtb rims with their rubber rim strip, but don't play well with stans rim and rim strip - burp far easier than say schwalbe on stans.

  74. #474
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    Wide Rims? Don't believe the hype...

    I agree with Craig's statement, it takes a critical mass to progress and make changes. Tire manufacturers are not going to invest in design and tooling to make tires for rims that are just a relatively small portion of the market.

    I do believe that some of the bigger players will be making moves into this wider rim trend and tires will eventually follow. Specialized is not exactly a small company in the bike biz. You can bet if they see enough success with their Fatties then the tires for them will come as well as more DH specific rims and tires.

    I'll also add to this discussion that larger tires also equate to additional clearance on forks and bike frames. You can't change one thing without impacting another. We do ride bikes, they're not really that complex but the components need to be compatible to make the whole bike work.

    What pharmaboy says is true regarding wtb tires and Stan's rims. They really don't fit on Stans rims at all! WTB does not even recommend the combination of their tires on Stans rims.
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  75. #475
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    Quick Update: I9 did not respond (in any way) to the question I posed to them via their website. So I have nothing to report back.

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    My camber evo came equiped with Fattie ALs and I rode it one time that way before switching to my normal wheels - roval control carbons. I do feel the wider profile rim with Purgatorys front and rear did have a slight handling advantage over the narrow carbon controls. A buddy of mine who comes from the MX world, who is extremely in tune with his set ups, just purchased a pair of roval fattie carbon traverse wheels. He loves them. He also uses Purgatory tires on the front and we measured his tire profile and mine back to back. His tires were around 2.3mms wider than mine, matted, tubeless running his desired preasure (23psi). I typically run 24-25psi on mine.

    I think there is an ever so slight advantage to the fatties, but it isn't anything like going from a 2.0 tire to a 2.3. Having said that, as mentioned above, with advances in tire designs, I can only see the advantages in the handling department only getting better. I don't think they are going to be a manadatory upgrade for everyone, but for those who like to push the edge, espescially pointed down, I could see it.

    Just my opinion.

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  77. #477
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by craigsj View Post
    I find it very disappointing how seldom advances come from larger manufacturers.
    I agree, though I also don't find it surprising. The bigger the mfr, the more the beureaucratic/administrative momentum is built into each move.
    Now throwing money to an "edgy" sub-brand or "development" entity could be interesting, but most shareholders are looking for quarterly dividends and couldn't care less about anything other than performance.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  78. #478
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    Not to hijack the OP's thread, but the majority of this thread has not dealt with downhill riding anyway. Just read all 20 pages of this thread trying to get some insight.
    Question for the one or two folks who posted that they ride the roval traverse fattie wheels in this thread: what tires have you tried with his wheel set and which ones worked the best in your opinion?
    Planning to put a wheelset with some wider rims on my 2012 specialized S works epic with longer travel after market fork, that is used for trail riding/AM rather then cross country. Have to deal with very slippery wet roots/rocks commonly where I ride, which require running lower pressures for traction. Would like to get rid of the tire squirm and gain better traction in corners in the wet with fatter rims.
    Presently running stock roval control sl wheelset w/ 21mm ID W/ Nobby Nic 2.35's fr & back, 17 & 19 psi, and no, for all the flamers in this forum (more than the usual bunch of immature people in here), I have never broken a rim, in spite of riding faster than most of the other people in our area.
    Thanks for your help.

  79. #479
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    i rode the Roval traverse fatties with a butcher control up front and slaughter in back. it didn't feel too blocked off, could still turn just fine with 650b

  80. #480
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    Quote Originally Posted by meltingfeather View Post
    I agree, though I also don't find it surprising. The bigger the mfr, the more the beureaucratic/administrative momentum is built into each move.
    Now throwing money to an "edgy" sub-brand or "development" entity could be interesting, but most shareholders are looking for quarterly dividends and couldn't care less about anything other than performance.
    So what you are saying is that the people with the capacity and financial security to R&D stuff prefer to exploit those who don't to test the market and for increased corporate gain?

  81. #481
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    Quote Originally Posted by jmcdev1 View Post
    Not to hijack the OP's thread, but...
    http://forums.mtbr.com/29er-componen...es-922275.html

  82. #482
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    Quote Originally Posted by jmcdev1 View Post
    Not to hijack the OP's thread, but the majority of this thread has not dealt with downhill riding anyway. Just read all 20 pages of this thread trying to get some insight.
    Question for the one or two folks who posted that they ride the roval traverse fattie wheels in this thread: what tires have you tried with his wheel set and which ones worked the best in your opinion?
    Planning to put a wheelset with some wider rims on my 2012 specialized S works epic with longer travel after market fork, that is used for trail riding/AM rather then cross country. Have to deal with very slippery wet roots/rocks commonly where I ride, which require running lower pressures for traction. Would like to get rid of the tire squirm and gain better traction in corners in the wet with fatter rims.
    Presently running stock roval control sl wheelset w/ 21mm ID W/ Nobby Nic 2.35's fr & back, 17 & 19 psi, and no, for all the flamers in this forum (more than the usual bunch of immature people in here), I have never broken a rim, in spite of riding faster than most of the other people in our area.
    Thanks for your help.
    I just got some Derby DH rims on my Ibis. I'm using butcher and slaughter for my tires and they are incredible in regards to traction. I can feel when the breaking point is though a lot sooner but it doesn't bother me. I live in Washington so I deal with a lot of slippery wet terrain. I have heard that slaughter is not very good for wet... I don't have enough experience using different tires. It's been working great for me!
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  83. #483
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    Thanks for the link to that thread, old ranger. Wasn't aware of it.
    I will also get a chance to try the butcher and slaughter on this wheel set when I borrowed my friends wheels soon. Thanks for the feedback guys.

  84. #484
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    I built a front Dually 45mm rimmed wheel to try 29+ for my rigid, was trying to figure what I'd run on the rear since it won't take a 29+, so widest would be a 29er 2.4" and wasn't sure if a Dually45 for that size tyre would be overkill or a 35mm rim would be enough. Decided to do some experimenting and threw a 2.25" Smorgasbord on the wheel, it's casing grew by 4mm (as wide as the 2.4" Chunky Monkey on an i25 rim). Rode it and couldn't believe the change in the tyre, no rolling or squirming, just turn or lean the bike into the corner and you had solid traction (I tried this tyre on the front once, did not like it).

    Decided to pull that tyre off and mount a 2.4" Chunky Monkey, it's casing grew about 3.5mm and profile flattened out a bit, will be riding it tomorrow, but I think it'll grip insane. These two tyres IMHO are a good choice as on "normal <25mm internal rims, the tread is quite round and it squares off just a bit on the 45mm rims making the edge knobs just that bit easier to get too without extreme lean angles.

    Pics attached of the Chunky Monkey on Dually45 and WTB i25, so that's an internal width difference of 14mm. Needless to say, I'm no pro anything, I absolutely love what the wider rim has done to how the tyre works and how solid it now is at low pressures without squirm, just like when I put my first set of decent "Fig" rims on my car coming from the standard factory rims, night and day difference.

    Quote Originally Posted by jmcdev1 View Post
    Not to hijack the OP's thread, but the majority of this thread has not dealt with downhill riding anyway. Just read all 20 pages of this thread trying to get some insight.
    Question for the one or two folks who posted that they ride the roval traverse fattie wheels in this thread: what tires have you tried with his wheel set and which ones worked the best in your opinion?...... Thanks for your help.
    Attached Thumbnails Attached Thumbnails Wide Rims?  Don't believe the hype...-dscn1655_web.jpg  

    Wide Rims?  Don't believe the hype...-dscn1653_web.jpg  

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    You're doing mtbr wrong, you're supposed to get increasingly offended by the implications that you're doing ANYTHING wrong.

  85. #485
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    Just for some reference here; Mitch Ropelato is running the Roval Traverse SL Fatties on his Specialized Enduro 29r pro enduro bike as was stated earlier in this thread. I saw a video of his enduro bike on Vital MTB and he runs the Butcher and Slaughter tires on the SL Fatties. He also used the same Enduro 29 bike to race the Taxco Urban DH race with the SL Fatties and same tires above. There are at least 4 riders that I know of on the pro enduro circuit racing on these wide carbon wheels so it looks to be more than just hype. Here's a link to Kelly McGarry's Taxco DH run to give you and idea of what Ropelato ran these wheels and tires down. https://www.youtube.com/watch?v=sITW5tr7KQg

  86. #486
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    Quote Originally Posted by LyNx View Post
    I built a front Dually 45mm rimmed wheel to try 29+ for my rigid, was trying to figure what I'd run on the rear since it won't take a 29+, so widest would be a 29er 2.4" and wasn't sure if a Dually45 for that size tyre would be overkill or a 35mm rim would be enough. Decided to do some experimenting and threw a 2.25" Smorgasbord on the wheel, it's casing grew by 4mm (as wide as the 2.4" Chunky Monkey on an i25 rim). Rode it and couldn't believe the change in the tyre, no rolling or squirming, just turn or lean the bike into the corner and you had solid traction (I tried this tyre on the front once, did not like it).

    Decided to pull that tyre off and mount a 2.4" Chunky Monkey, it's casing grew about 3.5mm and profile flattened out a bit, will be riding it tomorrow, but I think it'll grip insane. These two tyres IMHO are a good choice as on "normal <25mm internal rims, the tread is quite round and it squares off just a bit on the 45mm rims making the edge knobs just that bit easier to get too without extreme lean angles.

    Pics attached of the Chunky Monkey on Dually45 and WTB i25, so that's an internal width difference of 14mm. Needless to say, I'm no pro anything, I absolutely love what the wider rim has done to how the tyre works and how solid it now is at low pressures without squirm, just like when I put my first set of decent "Fig" rims on my car coming from the standard factory rims, night and day difference.
    Hmm i'd like to see that same tire mounted on an Arch EX for comparison.
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  87. #487
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    I won't bring anything scientific to the discussion just my own experience.

    I put on some Roval Fattie Carbons on my E29. Previously I had been running 23mm iWidth light-bicycle rims. These wheels arrived in January after ordering them in August. I put them on and actually "forgot" about them until I cranked up the season a few weeks ago. So I had no expectations when I headed out as opposed to the normal "Hey I bought this expensive thing let's see if I can tell the difference".
    I used the same tires, Butcher 2.3 front and Purgatory 2.3 back, normal pressure (26psi).

    I remember thinking "wow, really hero dirt today", and "man I'm getting nice grip in the corners" several times. It was only when I got home that I remembered I had a brand new "wide" wheelset on the bike.

    So for kind of a blind test, I felt the wheels made a noticeable improvement in cornering grip or at least cornering confidence. I had been running my previous setup all summer/fall going riding every weekend and more so I was very familiar with how the last setup felt.

    Plus, they make the tires look really burly so that's cool.

  88. #488
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    Is anyone REALLY hyping wider rims??

    Wide Rims?  Don't believe the hype...-wider.jpg

    Nevermind.....carry on......

  89. #489
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    Quote Originally Posted by PhxChem View Post
    Is anyone REALLY hyping wider rims??

    Click image for larger version. 

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    Nevermind.....carry on......
    If you think that's hype you should look up the definition of the word.

    Here are a few from this site:
    2. Exaggerated or extravagant claims made especially in advertising or promotional material...
    3. An advertising or promotional ploy...
    4. Something deliberately misleading; a deception: ... To publicize or promote, especially by extravagant, inflated, or misleading claims...

    The example you provide meets none of these definitions. Not all ads are hype, this one is remarkably understated.

  90. #490
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    Quote Originally Posted by craigsj View Post
    If you think that's hype you should look up the definition of the word.

    Here are a few from this site:
    2. Exaggerated or extravagant claims made especially in advertising or promotional material...
    3. An advertising or promotional ploy...
    4. Something deliberately misleading; a deception: ... To publicize or promote, especially by extravagant, inflated, or misleading claims...

    The example you provide meets none of these definitions. Not all ads are hype, this one is remarkably understated.
    Except for the picture. Most people can't do that on a mountain bike. And the ad might suggest that you can in an indirect or subliminal way, if you buy their wide rims.

  91. #491
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    Except for the picture. Most people can't do that on a mountain bike. And the ad might suggest that you can in an indirect or subliminal way, if you buy their wide rims.

    Lmao, and kids belief they can be superman. Wth is the difference? Oh wait there isn't one. Pretty much no one except little kids and those with no education beyond elementary school would "think the rims makes them able to do that"

  92. #492
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    Quote Originally Posted by tigris99 View Post
    Lmao, and kids belief they can be superman. Wth is the difference? Oh wait there isn't one. Pretty much no one except little kids and those with no education beyond elementary school would "think the rims makes them able to do that"
    You can laugh all you want, but subliminal advertising works on the subconscious mind and is an effective marketing tool.

  93. #493
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    You can laugh all you want, but subliminal advertising works on the subconscious mind and is an effective marketing tool.
    Agreed
    I like to fart when I'm in front of you on a climb:skep:

  94. #494
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    You can laugh all you want, but subliminal advertising works on the subconscious mind and is an effective marketing tool.
    But subliminal advertising is not hype. The suggestion was that this ad was an example of hype. It's just an example of plain old advertising.

  95. #495
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    Quote Originally Posted by craigsj View Post
    But subliminal advertising is not hype. The suggestion was that this ad was an example of hype. It's just an example of plain old advertising.
    It can be hype, please see post number 490.

  96. #496
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    Quote Originally Posted by craigsj View Post
    But subliminal advertising is not hype. The suggestion was that this ad was an example of hype. It's just an example of plain old advertising.
    Most advertising is hype. They make claims they can't back up. "Wider profile" is probably the only statement there that is unambiguous and can be backed up, the rest is puffery

  97. #497
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    It's a pretty good ad. And, it's not an all out lie like some ads you see.

  98. #498
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    "No actually if you look at it from a certain angle it's TOTALLY UNHYPED."

    Why the f*ck is this argument even happening?

  99. #499
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    It can be hype, please see post number 490.
    I saw post 490. Nowhere in the picture do they suggest you can ride like that if you had wider rims. If they did then that would be hype, instead it's merely advertising. There's a difference.

    Quote Originally Posted by pharmaboy View Post
    Most advertising is hype. They make claims they can't back up. "Wider profile" is probably the only statement there that is unambiguous and can be backed up, the rest is puffery
    No, most advertising is not hype. Hype means something specific.

    Now, if you think "more support, more traction, more control" are exaggerated or extravagant claims then you may claim hype...but you will lose that argument. Wider rims are used across many industries for just these reasons. It's a circular argument and those who reject these basic claims are deniers, nothing more.

  100. #500
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    Quote Originally Posted by craigsj View Post
    I saw post 490. Nowhere in the picture do they suggest you can ride like that if you had wider rims. If they did then that would be hype, instead it's merely advertising. There's a difference.


    No, most advertising is not hype. Hype means something specific.

    Now, if you think "more support, more traction, more control" are exaggerated or extravagant claims then you may claim hype...but you will lose that argument. Wider rims are used across many industries for just these reasons. It's a circular argument and those who reject these basic claims are deniers, nothing more.
    Haha, I guess you didn't understand what we were talking about when we were talking about subliminal advertising. That's a type of subliminal advertising.

  101. #501
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    Haha, I guess you didn't understand what we were talking about when we were talking about subliminal advertising. That's a type of subliminal advertising.
    Haha, and I guess you need it explained to you what the difference between hype and effective advertising is.

    Do you believe that drinking Budweiser gets you the girls? Do you believe that are literally claiming that in their commercials? After getting turned down at the bar with Bud in hand, would you run home and start a forum thread entitled "Budweiser? Don't believe the hype..."?

  102. #502
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    Quote Originally Posted by Preston67 View Post
    I won't bring anything scientific to the discussion just my own experience.

    I put on some Roval Fattie Carbons on my E29. Previously I had been running 23mm iWidth light-bicycle rims. These wheels arrived in January after ordering them in August. I put them on and actually "forgot" about them until I cranked up the season a few weeks ago. So I had no expectations when I headed out as opposed to the normal "Hey I bought this expensive thing let's see if I can tell the difference".
    I used the same tires, Butcher 2.3 front and Purgatory 2.3 back, normal pressure (26psi).

    I remember thinking "wow, really hero dirt today", and "man I'm getting nice grip in the corners" several times. It was only when I got home that I remembered I had a brand new "wide" wheelset on the bike.

    So for kind of a blind test, I felt the wheels made a noticeable improvement in cornering grip or at least cornering confidence. I had been running my previous setup all summer/fall going riding every weekend and more so I was very familiar with how the last setup felt.

    Plus, they make the tires look really burly so that's cool.
    Quote Originally Posted by scottie mac View Post
    My camber evo came equiped with Fattie ALs and I rode it one time that way before switching to my normal wheels - roval control carbons. I do feel the wider profile rim with Purgatorys front and rear did have a slight handling advantage over the narrow carbon controls. A buddy of mine who comes from the MX world, who is extremely in tune with his set ups, just purchased a pair of roval fattie carbon traverse wheels. He loves them. He also uses Purgatory tires on the front and we measured his tire profile and mine back to back. His tires were around 2.3mms wider than mine, matted, tubeless running his desired preasure (23psi). I typically run 24-25psi on mine.

    I think there is an ever so slight advantage to the fatties, but it isn't anything like going from a 2.0 tire to a 2.3. Having said that, as mentioned above, with advances in tire designs, I can only see the advantages in the handling department only getting better. I don't think they are going to be a manadatory upgrade for everyone, but for those who like to push the edge, espescially pointed down, I could see it.

    Just my opinion.

    Scottie

    You'll get even more out of the wide rims when you drop your pressure by 4-5psi. Think fat bikes. Wider wheels/tires=lower pressure=more traction.
    I'm at 15-16 front and 20 rear with 2.2 XR1s.

  103. #503
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    For those of you reviewing this thread, in the hopes there might be a relevant comment. Don't try 15psi front and 20psi rear on a downhill (DH) bike with the rims and tires available in 2015. The only conditions I can think of that would warrant those low pressures are a VERY muddy race course where traction is severely limited, and you don't have mud spikes to use.

    On average conditions - those pressures wouldn't even support my 95lbs. 11 year old in the turns or rocks.

    Edit: again, I'm providing these recommendations for a downhill bike. To clarify, that means you do not have to pedal it uphill, and for the majority of the time, you are pointed downhill at speeds between 15 mph and 35mph encounter rocks, turns and berms at those speeds. Maybe faster.

  104. #504
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    Quote Originally Posted by Ridnparadise View Post
    So what you are saying is that the people with the capacity and financial security to R&D stuff prefer to exploit those who don't to test the market and for increased corporate gain?
    not at all... wtf?
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  105. #505
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    Quote Originally Posted by oldranger View Post
    For those of you reviewing this thread, in the hopes there might be a relevant comment. Don't try 15psi front and 20psi rear on a downhill (DH) bike with the rims and tires available in 2015. The only conditions I can think of that would warrant those low pressures are a VERY muddy race course where traction is severely limited, and you don't have mud spikes to use.

    On average conditions - those pressures wouldn't even support my 95lbs. 11 year old in the turns or rocks.

    Edit: again, I'm providing these recommendations for a downhill bike. To clarify, that means you do not have to pedal it uphill, and for the majority of the time, you are pointed downhill at speeds between 15 mph and 35mph encounter rocks, turns and berms at those speeds. Maybe faster.
    The forum won't let me give you any more rep right now, sorry. But a normal 26, 27 or 29" MTB tire does not have enough air volume to run 15psi without riding the rim. It's very basic physics. The notion of wider rims allowing lower tire pressures was thoroughly debunked several times in this thread, but people still believe it. LOTS of people who are probably itching to give you and me negative rep right now!

    Fatbikes can run 15 psi - they have a tad more air volume. 29+ (29x3) can probably do it as well.

    Explanations for extremely low pressures on normal MTB tires:
    1) defective air pressure gauge
    2) rolling around on their rims without knowing it
    3) never takes a fast corner
    4) doesn't drop or jump
    5) doesn't hit rocks or roots at high speed

  106. #506
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    Thoroughly debunked?

    What I see here is a mix of anecdotal musings and a bit of marketing material. No doubt people have very disparate opinions about what, if any, performance changes you can expect from going to a wider rim. Some "feel" no change and some "feel" a huge difference. There are so many variables involved (terrain, tire design, riding style, etc.) and we are nowhere close to thoroughly debunking anything. Your perspective on things should dictate whether you spend your coin on a wider wheel or not.

    I've started a list of professions you probably aren't involved in:

    1) Statistician
    2) Physicist
    3) Mechanical engineer
    4) Judge
    5) Economist
    6) Political scientist
    7) Theoretical mathematician

  107. #507
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    Quote Originally Posted by ColinL View Post
    Fatbikes can run 15 psi - they have a tad more air volume. 29+ (29x3) can probably do it as well.
    In the old days of Nokian Gazzaloddis, we did run under 20 psi. But that's a 26x3" tire with a stupidly stiff casing that required motorcycle tire levers to install onto a rim. Darn thing would practically hold up the weight of the bike with no air in it.

  108. #508
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    Simple issue is this, wider means lower pressure allowed, simply based on increase in contact patch (which is where weight is supported). Same weight over increased area allows lower pressure to support the load.

    Increased contact patch also mean more rubber in contact with the ground. Equals more traction.

    In comes the hype: The changes aren't that big, in a scientific type sense. Lower pressures, from a 17mm inner to a 30mm inner width, ya that's something you'd notice with a few psi. 23/25 up to 30mm inner, its nothing more than pressure variance you get with weather changes. Really low pressures people think is the greatest thing, ya if your a low speed rock crawler. Beyond that there is a reason why burping is a problem, same reason any tubeless tire on car, motorcycle, etc, can and does loose tire off bead on a hard turn. Low pressures at speed is just asking for problems. wonder why I never dinged a rim....oh wait cause I run enough pressure to support the weight so I don't tag my rims when it gets rough.

    Fat bikes low pressures, its for float and allowed pressures are directly an effect of volume. You increase contact patch by 2-3x, you can run less pressure, increase contact further for more float and traction.

    Traction, that's been proven for decades, wider is better. No hype or anything there. Just like going from a 1.9 tire to a 2.4, traction just BETTER. Equal tire, bike, etc, wider is going to be better for traction in all aspects.

  109. #509
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    Quote Originally Posted by tigris99 View Post
    Simple issue is this, wider means lower pressure allowed, simply based on increase in contact patch (which is where weight is supported). Same weight over increased area allows lower pressure to support the load.

    Increased contact patch also mean more rubber in contact with the ground. Equals more traction.
    I think we can all agree that bicycle tires are supported by air pressure, and that the tire carcass itself does not offer any meaningful support. Isn't that evident by handling any unmounted tire, or by observing a bicycle at rest on a flat tire? The specific pressure required is determined by the tire, certainly - but the manufacturer has thoughtfully printed this on the side of the tire.

    Consider this in contrast to run-flat car tires, which are specifically built to have a really tough sidewall and tire carcass that can support the weight of the car temporarily with low / no air pressure. You can't do that with a mountain bike tire.

    So, regardless of the shape of the contact patch, with the same tires on different wheels you have the same air volume --excluding any differences to the rim bead depth & shape-- and same air pressure required to support a given usage.

    Also, let's not overlook that the side knobs on tires are angled and meant to be used when the bike is leaned into a corner. If they're fully engaged when the bike is upright, yes, I would agree you've got more traction. You've also got a lot more rolling resistance, and square tires are kind of hard to lean compared to rounded.

  110. #510
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    MTBR is hilarious. It's really the only bike forum where you can find this kind of stuff. "You are CLEARLY not a statistician or a physicist!"

    ZING. Got him!

    But anyway...

    Explanations for extremely low pressures on normal MTB tires:
    1) defective air pressure gauge
    2) rolling around on their rims without knowing it
    3) never takes a fast corner
    4) doesn't drop or jump
    5) doesn't hit rocks or roots at high speed
    This is pretty accurate.

  111. #511
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    Quote Originally Posted by ColinL View Post
    I think we can all agree that bicycle tires are supported by air pressure, and that the tire carcass itself does not offer any meaningful support.

    This is so untrue, I don't even know where to start.

  112. #512
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    Some of the lack of experience in this thread is breathtaking.

  113. #513
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    Quote Originally Posted by turbodog View Post
    Some of the lack of experience in this thread is breathtaking.
    To say the very least! I'd probably get in trouble If I said what I really wanted to say.

  114. #514
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by turbodog View Post
    Some of the lack of experience in this thread is breathtaking.
    Quote Originally Posted by Mountain Cycle Shawn View Post
    To say the very least! I'd probably get in trouble If I said what I really wanted to say.
    So very true and I'm also trying to behave myself here.

    To all here: It would be great to keep this discussion to constructive input! If you haven't ridden any of the wider rims then I suggest you take a test ride on any of them then bring your feedback from that experience here. Otherwise it's all theories and suppositions!
    Function in disaster, finish in style.

  115. #515
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    It's all opinion with nothing to back it up. And you know what they say about that!

  116. #516
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    I came from Stan Flow Ex and now I have a pair of Derby's. Stuck with the same specialized butcher up front and now run slaughter in the back. Granted a lot of things changed; Alu to Carbon, wide to WIDE, tire pressure difference, etc etc. but I am thoroughly enjoying my wide rims. traction is incredible but I do feel it breaking loose on flat turns sooner. I'm looking forward to tire companies accompanying these wide tires someday.

    Maybe a 2.2 inch tire with some crazy side knobs?
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  117. #517
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by Mountain Cycle Shawn View Post
    It's all opinion with nothing to back it up. And you know what they say about that!
    OK, you obviously have opinions but I haven't found much substance to them here in this thread. So why don't you pick a DH trail, same day, bike, same tires with your normal AM/ DH rim and a set of wide rims. Run them back to back multiple times, average your times in each then let us know what your findings are.
    Function in disaster, finish in style.

  118. #518
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    Quote Originally Posted by ColinL View Post
    ...So, regardless of the shape of the contact patch, with the same tires on different wheels you have the same air volume --excluding any differences to the rim bead depth & shape-- and same air pressure required to support a given usage....
    No true.
    A quick schematic:
    Wide Rims?  Don't believe the hype...-wide.jpg
    Same tire on both, the wider the rim get, the more volume you have.

  119. #519
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    Can you redo that diagram with a realistic difference between the internal rim widths?

    In that image you are comparing a 19mm wide rim to a 35mm wide rim. Try 25mm to 29mm. That's more appropriate.

  120. #520
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    The exact numbers are irrelevant. If it's a wider rim you'll have a bigger volume, that's all.
    You may think that a small increase in rim width won't add enough volume to make a difference and I won't argue with you.
    The point is ColinL was just way too far in his arguments.

  121. #521
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    You might also re-draw it with a tire that doesn't inflate like a balloon.

    Assuming the tire doesn't change, it would not be possible for it to fit on a wider rim and yet not lose any height / rolling diameter.

    That extra contact patch has to come from somewhere, right? And it comes from a change in tire profile. It is more square and less round, in real life, unlike your drawing.

  122. #522
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    Quote Originally Posted by manitou2200 View Post
    OK, you obviously have opinions but I haven't found much substance to them here in this thread. So why don't you pick a DH trail, same day, bike, same tires with your normal AM/ DH rim and a set of wide rims. Run them back to back multiple times, average your times in each then let us know what your findings are.
    I'm not you. You need to go do those things for yourself to decide if they are right for you. We could tell you how much better wide rims are, till we're blue in the face. You won't get it, till you try it. Go try it. This is the whole problem here. At least half of you want to spout off at the mouth and have never tried wide rims.

  123. #523
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    It doesn't matter, any profile you fancy, it will still have a bigger volume if the rim is wider.
    In the drawing above, the curve representing the tire section is the exact same lenght in both views.

  124. #524
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by Mountain Cycle Shawn View Post
    I'm not you. You need to go do those things for yourself to decide if they are right for you. We could tell you how much better wide rims are, till we're blue in the face. You won't get it, till you try it. Go try it. This is the whole problem here. At least half of you want to spout off at the mouth and have never tried wide rims.
    Dude, I already know the difference and benefits of the wider rims. I own rims with ID's from 22-40mm. I have a set of flow rims and the Roval SL Fatties mounted with the same tires. I'm just tired of all the ******** comments from so called riders here who've never ridden wider rims yet seem to know or are trying to hypothesize that they do not work.

    The other dumb ass argument going on here is the volume change debate. Think about this, if the bed width of the rim widens, then there is more area between the beads of the tire when they are seated. The internal circumferential cross section of the tire itself will not change so that's a given area. Wider rims give tires more volume period!

    Edit: My mistake I confused you for one of the naysayers of wide rims.
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    Another fact that still holds true a year after I started this thread is that in 2015 the bike manufacturers and race teams are still NOT spec'ing their downhill (DH) bikes with rims any wider than 23mm - 27.5mm inner width.

    And NO tire manufacturers are making DH casing tires specifically designed for these wider rims that are on the market from Niche players like Derby.

    In over a year, no one has proven this false. So I'm done contributing to this thread until that changes. I'll see you guys at the races on my old 26" DT Swiss FR600s. My name is Andy Richter. I'm an old guy, so if you pass me...try not to throw too much roost on me from your awesome wide rims. I'll keep my money for new tires, bearings, brake pads, and lessons for my son.

    P.S. Thanks for the vigorous debate.
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    So, moving on with the riders who have wide rim experience, we see added volume and a larger contact area. The area increase gives some more traction.
    The added volume allows lower air pressure before you get rim hits. From this we get an even larger contact patch with more deformation when going over bumps for even better contact and more traction.
    What else.
    The larger volume and lower pressure adds tire compliance from the standpoint of ride comfort. Small bump compliance that helps some forks which lack enough of that. This can be really good for hardtails. Maybe give added life to aluminum frame bikes.
    And more.
    The spreading apart of the tire beads gives better sidewall support. This is pretty significant for my riding. That support stops the tire tread from abruptly losing grip like when the less supported sidewall rolls over under quick cornering moves. I don't washout from a tracking mistake...basically anymore. I have time to recover instead of hitting the dirt. That's a big plus.
    It could be especially valuable for slow healers.

  127. #527
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    Quote Originally Posted by eb1888 View Post
    So, moving on with the riders who have wide rim experience, we see added volume and a larger contact area. The area increase gives some more traction.
    The added volume allows lower air pressure before you get rim hits.
    I can't say that I completely agree with you here. The area of the contact patch is solely dependent upon the load carried by the tire and the inflation pressure within it. A wider rim will change profile of the tire, which in turn will have an effect on the shape of the contact patch, and the pressure distribution within it.

    And added tire volume should actually make for a more linear spring rate while deforming over an obstacle, which would make rim hits more likely. Larger tires are less prone to pinch flats simply because there is a greater distance the tire must deform before the tire is totally compressed against the rim. But moving to a wider rim while using the same tire doesn't have much of an effect on the tire's section height.
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  128. #528
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    Quote Originally Posted by bholwell View Post
    I can't say that I completely agree with you here. The area of the contact patch is solely dependent upon the load carried by the tire and the inflation pressure within it. A wider rim will change profile of the tire, which in turn will have an effect on the shape of the contact patch, and the pressure distribution within it.

    And added tire volume should actually make for a more linear spring rate while deforming over an obstacle, which would make rim hits more likely. Larger tires are less prone to pinch flats simply because there is a greater distance the tire must deform before the tire is totally compressed against the rim. But moving to a wider rim while using the same tire doesn't have much of an effect on the tire's section height.
    Except, you don't seem to realize, probably because you haven't read the whole thread or other threads on the same subject, that a wider rim puts the sidewalls of the tires in a position to make them much stronger.

  129. #529
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    Except, you don't seem to realize, probably because you haven't read the whole thread or other threads on the same subject, that a wider rim puts the sidewalls of the tires in a position to make them much stronger.
    You seem to be making quite a few assumptions.

    Do you claim that because the sidewalls of the tire are slightly more vertical, they are able to take a compressive load, and that "makes them stronger"?
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    Quote Originally Posted by bholwell View Post
    You seem to be making quite a few assumptions.

    Do you claim that because the sidewalls of the tire are slightly more vertical, they are able to take a compressive load, and that "makes them stronger"?
    I know, right...?

  131. #531
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    Quote Originally Posted by bholwell View Post
    You seem to be making quite a few assumptions.

    Do you claim that because the sidewalls of the tire are slightly more vertical, they are able to take a compressive load, and that "makes them stronger"?
    It makes the sideway of the tire a lot stronger. The verticle force with a wide rim is able to be transferred up/down the whole length of the sidewall, instead of crossing the thin part of the sidwall because the sidewall is no longer shaped like a light bulb. It's the single biggest reason that makes wider rims better. In fact, it makes the sidewalls so much stronger that you are able to run much lower pressures. It's not the small increase of volumn that allows lower pressures, it's the better position of the sidewalls. And, roadies are also benefiting from wider rims, for the same reasons.

  132. #532
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    Except, you don't seem to realize, probably because you haven't read the whole thread or other threads on the same subject, that a wider rim puts the sidewalls of the tires in a position to make them much stronger.
    Yeah... professional tire designer doesn't realize what rim width does to profile, which he could (should?) have learned from MTBR, according to you.
    C'mon, dood.
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  133. #533
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    Quote Originally Posted by bholwell View Post
    You seem to be making quite a few assumptions.

    Do you claim that because the sidewalls of the tire are slightly more vertical, they are able to take a compressive load, and that "makes them stronger"?
    While you are here, can you please give your take on pressure. My understanding of the physics is that wider allows lower pressure before burping becomes an issue, but that rim strikes will occur more often because of the lower pressure - ie there is no real difference between normal and wide for rim strike occurrence.

  134. #534
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    Quote Originally Posted by meltingfeather View Post
    Yeah... professional tire designer doesn't realize what rim width does to profile, which he could (should?) have learned from MTBR, according to you.
    C'mon, dood.
    Tire designers have done the best they can with what they have been given. People want big tires, regardless of the skinny rims and that's what the tire companies have given us. Wait till tire companies start making tires for these wide rims. Then you'll really see some performance gains. The stronger sidewall is one reason why the narrower tires seen to work better with wide rims. Again, it's all about sidewall strength at supper low pressures that allows more tread to be in contact with the ground, without rim strikes.

  135. #535
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    It makes the sideway of the tire a lot stronger. The verticle force with a wide rim is able to be transferred up/down the whole length of the sidewall, instead of crossing the thin part of the sidwall because the sidewall is no longer shaped like a light bulb. It's the single biggest reason that makes wider rims better. In fact, it makes the sidewalls so much stronger that you are able to run much lower pressures.
    If this were true I could let all the air out of a tire mounted on wide rims and it'll hold the weight of the bike off the ground, whereas the same tire on a normal rim will bottom out under the weight of the bike. Too bad it doesn't work that way. You're telling me that a flimsy tire sidewall can support heavy compressive loads if you could just make it vertical, yeah, and you can push on a string if it's in a straight line. Pull the other one.

  136. #536
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    Quote Originally Posted by pharmaboy View Post
    While you are here, can you please give your take on pressure. My understanding of the physics is that wider allows lower pressure before burping becomes an issue, but that rim strikes will occur more often because of the lower pressure - ie there is no real difference between normal and wide for rim strike occurrence.
    Your understanding of the physics behind it jive with my own. Spacing the beads further apart gives the tire a more stable "base"; less of a pivot point. Imagine a rim so narrow that the beads are touching. I'd wager you'd be able to roll the inflated tire laterally with your hands fairly easily. Rider rim = more stable base = less lateral roll = less burping while cornering or landing a jump sideways. I think this is mostly why people claim they can ride a wider rim at lower pressures.

    Regarding rim strikes, since the volume of the tire is greater, the spring rate will be more linear, so based on that alone the likelihood of rim strikes should increase. There may be other factors at play, however. Imagine running over a tall skinny root at high speed. The height of the root is such that when the root is directly over the wheel's axle and the tire is compressed all the way to the rim, the tire does not come into contact with the ground at all. In this scenario, the contact patch of the tire is only contacting the root. A tire on a wider rim might allow the tire to spread out (width-wise) across the root more, effectively yielding a larger contact patch, and thereby helping reduce the chance of pinch-flatting. I would like to test this theory, but I'd need to make a bicycle wheel adapter for my company's Ektron vertical load tester.
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  137. #537
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    Quote Originally Posted by aerius View Post
    If this were true I could let all the air out of a tire mounted on wide rims and it'll hold the weight of the bike off the ground, whereas the same tire on a normal rim will bottom out under the weight of the bike. Too bad it doesn't work that way. You're telling me that a flimsy tire sidewall can support heavy compressive loads if you could just make it vertical, yeah, and you can push on a string if it's in a straight line. Pull the other one.
    Now you're just getting stupid. Of course the tire has to have air in it to do its job. That's the way it was all engineered. Mountain bike tires aren't Runflats. You wouldn't let all the air out of your air shock and expect it to work properly. Well, maybe you would but the rest of us wouldn't do that.

  138. #538
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    Quote Originally Posted by bholwell View Post
    Your understanding of the physics behind it jive with my own. Spacing the beads further apart gives the tire a more stable "base"; less of a pivot point. Imagine a rim so narrow that the beads are touching. I'd wager you'd be able to roll the inflated tire laterally with your hands fairly easily. Rider rim = more stable base = less lateral roll = less burping while cornering or landing a jump sideways. I think this is mostly why people claim they can ride a wider rim at lower pressures.

    Regarding rim strikes, since the volume of the tire is greater, the spring rate will be more linear, so based on that alone the likelihood of rim strikes should increase. There may be other factors at play, however. Imagine running over a tall skinny root at high speed. The height of the root is such that when the root is directly over the wheel's axle and the tire is compressed all the way to the rim, the tire does not come into contact with the ground at all. In this scenario, the contact patch of the tire is only contacting the root. A tire on a wider rim might allow the tire to spread out (width-wise) across the root more, effectively yielding a larger contact patch, and thereby helping reduce the chance of pinch-flatting. I would like to test this theory, but I'd need to make a bicycle wheel adapter for my company's Ektron vertical load tester.
    This is also true. Less of a light bulb effect going on.

  139. #539
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    As a guy who's done everything in the last 14 years from cat 1 XC in Wisconsin, Iowa, and the midwest, to DH runs in CO and CA and UT, let me just share this perception/observation: people ride mountain bikes VERY differently. even one person's "aggressive rocky DH run" is different than another's.
    So, for one person: "works great, no rim strikes at less psi, etc" good for you.
    For another person: "too many rim strikes, destroying rims, x tires work fine, y tires don't." Also good for you.

    Some people push bikes HARD on tame terrain, other people are easy on harsh terrain, and vice versa.

    Apples and oranges.

    Given that, thanks everyone for sharing your personal experiences with as much context as possible, and I appreciate the conversation, both the storytelling and the hypothesizing.

  140. #540
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    May be friday u work?

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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by rfxc View Post
    As a guy who's done everything[...] hypothesizing.
    So what you're saying is one rider's subjective trail impressions don't mean anything necessarily to the next rider... which is my motto. On MTBR though, each person's opinion is gospel (to them) and a universal law that applies to everyone.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  142. #542
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    Now you're just getting stupid. Of course the tire has to have air in it to do its job. That's the way it was all engineered. Mountain bike tires aren't Runflats. You wouldn't let all the air out of your air shock and expect it to work properly. Well, maybe you would but the rest of us wouldn't do that.
    You contradict your previous argument with this one. The point you make here is that the load is supported by the internal pressure, not the sidewalls. Yet previously you claim the opposite.

    It may be useful for you to clarify your use of 'work properly'. Are you saying that when inflated, the sidewalls support compressive loads? If so, it is useful to note that while riding the resulting deflection of the sidewall is supported by the internal pressure, not the sidewall itself. This mechanism of support, namely by pressure, is not controlled by the direction of the sidewall orientation. Instead, the sidewall is supported by the transfer of force via internal pressure which seeks to balance the tensile stresses and compressive forces on the tire. However, pressure is a scalar and not a vector quantity so there is no fundamental mechanism to support your argument.

    Said another way, pressure has no directionality so it cannot operate differently based on the angle of the sidewall.

    Please let me know if I missed an alternate mechanism you may be considering.
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  143. #543
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by ca_rider View Post
    Said another way, pressure has no directionality so it cannot operate differently based on the angle of the sidewall.
    uh... yes it does. Pressure always acts normal to the surface it is acting on. Change the angle of the surface (sidewall) and you change the resultant force (vector). Changing the action-reaction at the rim bead, which this translates to, as well as the sidewalk buckling, changes the behavior of the interface on both ends: tire-rim and tire-ground.
    Ever heard of a Hemi?
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  144. #544
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    I know you are a CE - I suggest you reconsider wrt projected area.

    Cheers.
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  145. #545
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    Funny watching people argue engineering points. everyone doesn't want huge tires that create steering lag and become very heavy. just skip the whole wide rim thing and just go full fat bike if that's what you want. wide rims are not new, neither are big tires. I've found people who like this setup spend most of their time straight up n down and not leaned. traction is cool and all but is not the end all of riding. you want traction but you also need some loss of traction in a predictable fashion. normal tires on ultra wide rims do not do that.
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  146. #546
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by ca_rider View Post
    I know you are a CE - I suggest you reconsider wrt projected area.

    Cheers.
    If this was directed at me (being a CE):
    F (vector) = PA is not independent of the orientation of the A. The orientation of the surface that the pressure is acting on defines the directional (vector) component of the force. This is not engineering but high school physics. Even a 5 minute lesson on wikipedia's pressure page will tell you that.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  147. #547
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    Quote Originally Posted by meltingfeather View Post
    So what you're saying is one rider's subjective trail impressions don't mean anything necessarily to the next rider... which is my motto. On MTBR though, each person's opinion is gospel (to them) and a universal law that applies to everyone.
    That's the situation across the Internet, personal experience trumps science. That's how we have an anti GMO movement, anti vaxers etc. The world is full of people who think anecdote trumps understanding.

    That anecdotal stuff is what originally drove the creation if this thread - people who have tried and loved the Kool Aide, convinced wide is better in every respect without a downside. Basic applied logic should tell anyone, that there has to be a downside and that there also has to be a point where wider is worse.

    The only reason I joined this thread is because one aspect of the preaching is about lower pressures, and the advice on the Chinese rims thread, has been about 5psi less with wider rims, and people are amazingly surprised that they are striking the rims and breaking them.

    The outcome of lower pressure is predictable by rudimentary physics, nay, even rudimentary logic, yet people continue to get advice to go far lower.

  148. #548
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    Quote Originally Posted by ca_rider View Post
    You contradict your previous argument with this one. The point you make here is that the load is supported by the internal pressure, not the sidewalls. Yet previously you claim the opposite.

    It may be useful for you to clarify your use of 'work properly'. Are you saying that when inflated, the sidewalls support compressive loads? If so, it is useful to note that while riding the resulting deflection of the sidewall is supported by the internal pressure, not the sidewall itself. This mechanism of support, namely by pressure, is not controlled by the direction of the sidewall orientation. Instead, the sidewall is supported by the transfer of force via internal pressure which seeks to balance the tensile stresses and compressive forces on the tire. However, pressure is a scalar and not a vector quantity so there is no fundamental mechanism to support your argument.

    Said another way, pressure has no directionality so it cannot operate differently based on the angle of the sidewall.

    Please let me know if I missed an alternate mechanism you may be considering.
    Air pressure is a constant here. Tires depend on air in them to keep the tire in the correct position so the tire can do its job properly. I'll give you my example: Spinergy Enduro wheels with a 26mm rim setup tubeless, can be pinch fattened by me at 25psi. With X King 2.4" tires. This setup has a lightbulb look to it. Where the rim is the part that screws into the socket and the tire is the light bulb. At 25 psi you can grab the tire with your hand and flex it back and forth. The tire is so round at the sidewalls that its in a very bad position to resist the forces acting on it. The same exact setup with 40mm rims can't be pinch flattened by me even at 15psi. Grab this tire with your hand and you can't flex the tire as much as the other setup. This setup no longer has the lightbulb look to it. You can now see, just by looking at it that the tire can now better handle the verticle forces being applied to it, because the sidewall is more verticle. And side loads are handled better because of the wider rim. The difference is not caused by air volumn. Because there is almost no change in air volumn between the two setups. This is because with the 40mm rims the tires circumference doesn't change, the side knobs actually get a tiny bit more narrow, but they stand up higher, the top of the tread flattens out a bit. The very center wants to fold in towards the rim, but it can't because of the increased sidewall tension. So, there are three things here that make the tire stronger with a 40mm rim. The tire sidewall is in a better position to handle verticle loads, the sidewall now has more tension and the wide rims help the tire deal with the side loads better. Now picture two light bulbs the same size. One has a 26mm socket end and one has a 40mm socket end. It's going to take a lot more force for you to grab and break off the light bulb with the 40mm base. It would also be harder to break that same bulb by holding the socket end and slamming it straight down on a flat surface, compared to the bulb with the 26mm base. Just picture in your mind how a big volumn tire changes as it goes from having a narrow width at the bead to having a wide width at the bead. Play that over and over in your mind until you see it and you'll understand. It just takes a while to get it.

  149. #549
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    Quote Originally Posted by bholwell View Post
    A tire on a wider rim might allow the tire to spread out (width-wise) across the root more, effectively yielding a larger contact patch, and thereby helping reduce the chance of pinch-flatting. I would like to test this theory, but I'd need to make a bicycle wheel adapter for my company's Ektron vertical load tester.
    This makes sense to me too. I think it has very little to do with the vertical-ness of the sidewalls, but rather that the force that the tire pushes back with is related to the pressure x length (or area) of the "flat-spot" due to tire deformation. And a wider rim causes a tire to put down a bigger flat spot. However, tire deformation forces are rather complicated due to a non-stretchy casing, so probably a real test is best instead of hypothesizing.
    Also, this benefit is totally cancelled out if you run a lower pressure.

  150. #550
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    Quote Originally Posted by pharmaboy View Post
    That anecdotal stuff is what originally drove the creation if this thread - people who have tried and loved the Kool Aide, convinced wide is better in every respect without a downside.
    One read of the original post shows this not to be true. The "anecdotal stuff" came from the OP, not the other way around. You're showing your bias here.

    Quote Originally Posted by pharmaboy View Post
    The only reason I joined this thread is because one aspect of the preaching is about lower pressures, and the advice on the Chinese rims thread, has been about 5psi less with wider rims, and people are amazingly surprised that they are striking the rims and breaking them.
    Yes, there is stupidity on both sides of the argument. That's what you get with tribalism and this has never been anything but a tribalist thread. When winning is all that matters, good information loses.

  151. #551
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    Quote Originally Posted by beanbag View Post
    This makes sense to me too. I think it has very little to do with the vertical-ness of the sidewalls, but rather that the force that the tire pushes back with is related to the pressure x length (or area) of the "flat-spot" due to tire deformation. And a wider rim causes a tire to put down a bigger flat spot. However, tire deformation forces are rather complicated due to a non-stretchy casing, so probably a real test is best instead of hypothesizing.
    Also, this benefit is totally cancelled out if you run a lower pressure.
    Absolutely. I'd wager I'm the only one in this thread who has actually performed vertical displacement testing on a tire in the lab. The sidewall of a bicycle tire does not handle vertical loads, as Mountain Cycle Shawn believes. The carcass of today's bicycle tires are so thin, it's simply not possible. Now if we're talking about 8 Ply Industrial tires at very low pressures on very narrow rims (compared to the design rim width), then yes, this theory has merit. But these tires are 8 ply in order to have a very high operating pressure to be able to carry a very high load, and they are always used on the specified design rim.
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  152. #552
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    In a light bulb shape tire and rim the load crosses a thin section of tire as if going through the side of the tire because of the tires angle. With a wide rim the force is able to travel through a much longer section of the sidewalk because the sidewall is now more verticle. There's a reason why they don't use rims and tires that have a lightbulb shape on dirt bikes.

  153. #553
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    Quote Originally Posted by Mountain Cycle Shawn View Post
    In a light bulb shape tire and rim the load crosses a thin section of tire as if going through the side of the tire because of the tires angle. With a wide rim the force is able to travel through a much longer section of the sidewalk because the sidewall is now more verticle.
    No.

    Quote Originally Posted by Mountain Cycle Shawn View Post
    There's a reason why they don't use rims and tires that have a lightbulb shape on dirt bikes.
    Yes, and it's because the tires are better supported laterally. The rim and tire widths of off-road motorcycles have nothing to do with supporting a vertical load. I honestly cannot believe you are attempting to educate me on tire dynamics.
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

  154. #554
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    Quote Originally Posted by bholwell View Post
    I honestly cannot believe you are attempting to educate me on tire dynamics.
    ROFLMAO.

    I'm pleased to see that I was right about air pressure supporting the tire, and I humbly admit that I was wrong about the air volume changing on a wider rim. However, the actual change is considerably less than montreal marc's original diagram.

    Still, I'm here to learn. I know the difference between opinion and fact. It's perfectly fine for people to have the opinion that they like wide rims. It remains to be seen that they are factually better in measurable ways.

  155. #555
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    Anecdotal stuff has its value because it usually involves a direct comparison between two different things. Tire A on 21mm inside rim and tire A on 30mm inside rim over the same terrain. A person gets very familiar with terrain features and handling limits when he rides the same loop many multiple times.
    No engineering degree is needed to register a ride and handling difference.
    A degree may help if a finite quantification of any difference was necessary.
    It's just not necessary for a large group of riders. They can get the experience without the numbers.
    You engineering guys who haven't ridden wides in a direct comparison aren't going to add much for that large group.
    Those who can make a direct comparison or do some other testing could be helpful for the non riding engineers.

    Wide Rims?  Don't believe the hype...-archexrim-nnic.jpgWide Rims?  Don't believe the hype...-cb35.30rimxr1.jpg

    Here's my example from actual riding.
    Nobby Nic vs XR1, pretty similar handling and sized tires.
    There is a major difference over the hardpack with rocky rooty segment and lots of different turn type terrain I have ridden thousands of times.
    That sidewall support at 4 psi lower pressure will not abruptly washout and put me on the dirt. The added volume and lower psi without rim hits contributes a lot of comfort from tire compliance. I know the feel of each feature of my trail. No way would I ever go back to skinny rims.
    The tire on the 30mm rim doesn't even look wide anyway, it looks normal. The ArchEx setup looks goofy.

  156. #556
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    Quote Originally Posted by ColinL View Post
    ROFLMAO.

    I'm pleased to see that I was right about air pressure supporting the tire, and I humbly admit that I was wrong about the air volume changing on a wider rim. However, the actual change is considerably less than montreal marc's original diagram.

    Still, I'm here to learn. I know the difference between opinion and fact. It's perfectly fine for people to have the opinion that they like wide rims. It remains to be seen that they are factually better in measurable ways.
    I believe it has been shown , factually, that wider rims support higher lateral loads with less deflection (as per Specialized's testing). What this means is that, IF your riding style/terrain allows you to run lower pressures without rim strikes, then you can benefit from riding wider rims as they will allow those lower pressures (hence larger patch, hence more traction) without the tire rolling on the rim. Of course that is assuming traction is a goal and the change in tire profile isn't too much of a trade off.
    It's just a flesh wound!

  157. #557
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    Some relevant statements made by Specialized engineer Jason Chamberlain: "...contact patch doesn’t change size with different wheel sizes – it just changes shape. The only way to truly increase your contact patch is to lower your pressure. The only way to lower your pressure is with larger volume." "...wider rims gives you more volume without increasing tire size and adding casing. It also better supports the sidewalls..." Roval Traverse Fattie SL Wheels - NSMB.com

    A review with images of the devices used by Specialized to measure deflection: First Ride: Roval Traverse Fattie Wheels - Super Wide and Super Fast - Pinkbike

    Art's Cyclery Blog with more relevant input on this subject: Art's Cyclery Blog » Science Behind the Magic | Wide MTB Rims

  158. #558
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    Quote Originally Posted by HillDancer View Post
    It also better supports the sidewalls...
    Oh gosh, ****ing imagine that!!

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    Here's what I-9 had to say:

    "Optimized inner rim width – With class leading Inner width to weight ratios already in place for our Torch series Aluminum rims, Industry Nine is no stranger to the recent push for wider inner width (IW) rims. So if wide is good, wider is better right? Based on our testing however, we found that there are optimal inner widths for each category of bike and tire:
    - Current Mtb. tire technology is based on established rim profiles. Tire designers create tread profiles with a specific orientation on the tire casing to function optimally on a given rim inner width. If the IW of a given rim is too far outside of this range the tread pattern (particularly the shoulder blocks) can no longer function properly.
    Based on our testing and feedback from tire manufacturers, we came to a consensus on ideal rim widths for given tire categories. XC and intermediate Trail tires (usually 1.9-2.25” widths) are designed to function best on 18-25mm IW rims. Aggressive Trail and Enduro tires (usually 2.2-2.4mm widths) are optimized for 21-29mm IW rims, and DH/Park tires (usually 2.3-2.7” widths) are optimized for 25-31mm IW rims. “Plus” size and Fat Bike tires form their own categories and are designed specifically for much wider rims, with 40+mm inner widths on “plus” size rims, and 60-90+ mm inner widths for fatbike rims depending on tire widths.
    - As many riders have experienced, rims on the narrow end of the IW scale offer poor tire support and tires easily fold over and lose traction under hard cornering, so in comparison narrow “old school” rims, a wider inner width offers a lot of advantages vs. traditional narrow IW rims.
    - Rims with exceptionally wide inner widths (for a given category) paired with a tire designed for much narrower rims, cause the cornering blocks on many tires to become so “square” that they no longer contact the trail surface in their the intended shear plane - causing a dramatic reduction in traction at the cornering limit or on of camber objects or sections of trail.
    - Rim and Tire Sidewall impact protection – with wider inner widths comes wider rim profiles overall. So for example a 35mm IW rim is generally going to have a 40+ mm outer width. On technical rocky trails a wider rim is much more susceptible to sidewall impact damage as the tire does not shield the rim from loose rocks, lateral impacts etc. Additionally the cornering tread blocks no longer shield the tire sidewalls from rocks leaving the tire much more susceptible abrasion and damage due to rock impacts.
    - Weight – all things being equal, a wider rim is going to be heavier. More surface area requires more carbon, which can completely offset the weight benefit of carbon rims.
    Taking this into account we designed the Pillar carbon series rims with inner widths which are in line or slightly wider than our current aluminum rim widths (depending on the model). The rims feature a hookless bead wall, which optimize the inner rim width of each model to be on the wide end of the spectrum for the intended tire and usage category. As tire design evolves there is no doubt that their will continue to be opportunities for wider rim technologies (after all no one wants to ride a 4.8” fatbike tire on a 19mm IW rim). However, we feel the PillarCarbon rims offer the prefect balance of IW, lateral stiffness, strength, and weight to accommodate today's XC, Trail, and Enduro Tires."

    First comment below the article:
    First Look: Industry Nine PillarCarbon Wheels - Mtbr.com

  160. #560
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    Here's what I-9 built for DH:
    First introduced in 2006, the I9 Enduro wheelset was built for those who wanted a bulletproof wheelset for aggressive riding. Tested extensively on the rigorous trails of Pisgah and Dupont State Forest, the new PillarCarbon Enduro 27.5-inch wheelset is ideally suited for long-travel full-suspension bikes. Featuring 32-spoke construction, 26.25mm inner rim width and 31mm outer rim width, the PillarCarbon Enduro 27.5-inch wheelset is still ultralight at just over 1400 grams while accommodating riders up to 220 pounds.

  161. #561
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    Sorry guys, I'm going back on my promise to leave the thread...I just couldn't pass up the latest comments with folks trying to 'school' bholwell on tire design.

    Bholwell, I didn't come right out and ask you last year what rim width you would recommend for competitive DH racers using the Minion DHR2, Minion DHF, and High Roller tires...but I would love to know your opinion.

  162. #562
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    Many riders have experienced a 30mm inside or larger rim working with a broad range of tires with a rounded tread profile. Relatively few tires are squaring off.
    It becomes possible to get more performance from the next lighter less aggressively profiled faster rolling tire offered in a manufacturer's line. So you don't always need as much knob for traction anymore.

    "- Rims with exceptionally wide inner widths (for a given category) paired with a tire designed for much narrower rims, cause the cornering blocks on many tires to become so “square” that they no longer contact the trail surface in their the intended shear plane - causing a dramatic reduction in traction at the cornering limit or on of camber objects or sections of trail."

    I don't think this statement by I-9 is specific enough to have value right now until a list is developed. Ibis says to pick tires with a rounded tread cap.

    Riding XC to All Mountain terrain where lower pressure will work without rim hits. Could be the areas that see the most benefit. DH not so much.

  163. #563
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    Quote Originally Posted by JLF1200 View Post
    Here's what I-9 had to say:
    (snipped)

    First comment below the article:
    First Look: Industry Nine PillarCarbon Wheels - Mtbr.com
    I sure hope everyone read this.

  164. #564
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by ColinL View Post
    I sure hope everyone read this.
    Makes perfect sense - rims should be matched to tires more or less.

  165. #565
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    Quote Originally Posted by oldranger View Post
    Sorry guys, I'm going back on my promise to leave the thread...I just couldn't pass up the latest comments with folks trying to 'school' bholwell on tire design.

    Bholwell, I didn't come right out and ask you last year what rim width you would recommend for competitive DH racers using the Minion DHR2, Minion DHF, and High Roller tires...but I would love to know your opinion.
    I designed the DHR2, High Roller II, and Shorty tire profiles on a rim with an inner width of 25mm. This isn't because I believe that a rim IW of 25mm is ideal for downhill riding/racing, but rather because that's what most people were running at the time. So if you don't stray too far from 25mm (say 30-32mm max) you'll likely be fine.

    This quote by I9, though worded strangely, is very apt:
    Rims with exceptionally wide inner widths (for a given category) paired with a tire designed for much narrower rims, cause the cornering blocks on many tires to become so “square” that they no longer contact the trail surface in their the intended shear plane - causing a dramatic reduction in traction at the cornering limit or on of camber objects or sections of trail.
    Once one leans in a flat corner at such an acute angle to the ground that the inside edge of the shoulder lug no longer makes good contact with the ground, cornering traction can dramatically drop off. So it makes sense that an XC tire that was designed on a 21mm IW rim will not perform well on a 40mm IW rim. In an ideal situation, the tire and rim should be designed to work together. The reality, however, is that severely limits your market. I can't imagine many people would want to buy a tire that was designed to work optimally on a rim with an inner width of A, when they own a rim with an inner width of B.

    Could I envision rims with an inner width of 36 or 40mm eventually becoming the norm for downhill racing? Yes. But it will likely be a slow evolution due the the reason given above.
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

  166. #566
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    So what it comes down to is: wider is better in certain applications, and narrower is better in certain applications. More importantly, as bholwell points out along with I9, is matching tire to rim and the intended purpose.

    At some point, wider rims, means wider tires, which means designing chainstays/seatstays and forks to allow for the extra width. This means longer cs/ss, higher bb, basically a geometry redesign. Which is fine, the industry has proven they can make 29" wheels work, so this is not a huge issue, and right now the rims are not wide enough to cause too much trouble with most bikes AFAIK.

    Maybe that is the reason behind the "+"size tires and bikes to match those, to fill in the gap between xc/trail/enduro bikes and fat bikes?

    Wider rims/ bigger tires means more weight. Right now I don't lack traction so I choose less weight. I could care less about ramming my bike into a curb and seeing if the wider rim makes it absorb better, I hop over the curb, and rocks when possible.

  167. #567
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    Quote Originally Posted by HillDancer View Post
    A review with images of the devices used by Specialized to measure deflection: First Ride: Roval Traverse Fattie Wheels - Super Wide and Super Fast - Pinkbike
    [/url]
    Wanted to jump in and point this out from the above article:

    The dozen or so journalists on hand provided a sample group for pinch flats and sidewall tears. There were only four, maybe five punctures over three full days of riding, three were sidewall injuries which required tubes. The rest were slow leaks which took longer than normal for the sealant to heal. Most took place on stage five, which began with a flat-out run over imbedded rocks. Looking back at the body of evidence, it appears that the survivability of a tire on the Traverse Fattie wheels is about the same as that same model fitted to a narrower rim.
    So, this works out to one tire failure in 10 rider-days. Last time I checked, that is not acceptable if you're a tire buyer, but it's great if you sell tires lol. These failures come from riding low pressures, presumably for better traction and more compliance on rough terrain - the wide rim is needed to maintain tire stability at these lower pressures. This altogether makes the wide rim concept a false premise:

    - If you're riding smoother terrain where there is little issue with sidewall flats, why are you riding low pressures? Higher pressures roll better and traction should be plentiful. Riding around on smooth terrain with wide rims and low tire pressures makes no sense. There is no need for an extra wide rim.

    - If you're riding rough terrain where rim strikes and sidewall tears could be much more frequent, you need to increase tire pressures accordingly to keep your wheels and tires intact. So with this extra pressure, tire stability should not be a problem on normal width rims. There is no need for an extra wide rim.

    I've only found one setup that let me do aggressive riding with very low pressures without sidewall tears or rapid rim damage - 2ply downhill tires with 500g motocross bike tubes - which provided padding for the rim and was extremely durable, though gradual rim damage did occur. Clearly not acceptable for trail riding with climbing involved.

    IMHO, people gravitating to wider rims and low pressures are often under gunned in their tire selection for trail riding - too narrow tires with wimpy knobs or marginal rubber compounds. Selecting gripper tires that still have low rolling resistance and acceptable weight solves the traction issue without having to resort to unreasonably low pressure and extra wide rims to accommodate it.

  168. #568
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    Quote Originally Posted by sherwin24 View Post
    So what it comes down to is: wider is better in certain applications, and narrower is better in certain applications. More importantly, as bholwell points out along with I9, is matching tire to rim and the intended purpose.

    At some point, wider rims, means wider tires, which means designing chainstays/seatstays and forks to allow for the extra width. This means longer cs/ss, higher bb, basically a geometry redesign. Which is fine, the industry has proven they can make 29" wheels work, so this is not a huge issue, and right now the rims are not wide enough to cause too much trouble with most bikes AFAIK.

    Maybe that is the reason behind the "+"size tires and bikes to match those, to fill in the gap between xc/trail/enduro bikes and fat bikes?

    Wider rims/ bigger tires means more weight. Right now I don't lack traction so I choose less weight. I could care less about ramming my bike into a curb and seeing if the wider rim makes it absorb better, I hop over the curb, and rocks when possible.
    This isn't all true. Most of the wide carbon rims are as light or lighter then the aluminum rims they are replacing. Just because the rims are getting wider, that doesn't meant the tire people will make the tires wider for these rims. Hopefully, they will make tires that work best for these rims. And, that doesn't necessarily mean that they have to be wider then they are now. Part of the reason wide rims work so good, is the fact that the tire isn't to wide for the rim. So, it doesn't make sense to just keep making the tires wider. And, right now, it seems that the narrower tires actually work better on wider rims. Then there is the weigh penelty, if tires get any wider. We don't want heavier tires.

  169. #569
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    Sorry, I meant wheels of the same material. a narrower carbon rim is still lighter than a wider carbon rim typically. It would seem that aluminum in over 30mm internal would become weight prohibitive by having to add more material to support the width. Carbon would definitely be the best for wider for that reason alone. Perhaps that will help bring the cost of carbon down some over time, as more companies spec carbon wheels just to give the masses a wide wheel with decent weight.

    I am not against wide rims, been riding 25mm internal rims for a year and that was wide not long ago. But given the choice, I will take less weight over wider considering I don't feel I need any of the advantages wider offers given where and how I ride.

  170. #570
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    Quote Originally Posted by bholwell View Post
    But it will likely be a slow evolution due the the reason given above.
    I dunno, the bike industry was pretty ruthless in killing off the 26" wheel.

  171. #571
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    Quote Originally Posted by sherwin24 View Post
    Sorry, I meant wheels of the same material. a narrower carbon rim is still lighter than a wider carbon rim typically. It would seem that aluminum in over 30mm internal would become weight prohibitive by having to add more material to support the width. Carbon would definitely be the best for wider for that reason alone. Perhaps that will help bring the cost of carbon down some over time, as more companies spec carbon wheels just to give the masses a wide wheel with decent weight.

    I am not against wide rims, been riding 25mm internal rims for a year and that was wide not long ago. But given the choice, I will take less weight over wider considering I don't feel I need any of the advantages wider offers given where and how I ride.
    AC Wide Lightnings are 1569g and 29.3 inside aluminum. Roval has aluminum Fatties and Syntace has several sizes.

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  172. #572
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    Tires don't need to be wider but the knobs repositioned for the new profile. Wide doesn't have to mean heavy and a smaller tire can be used for a big footprint. Tire design may not be there yet but I'm sure it will the way things are going. I'm still using the old wide Flow EX.
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  173. #573
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    Quote Originally Posted by Travis Bickle View Post
    Tires don't need to be wider but the knobs repositioned for the new profile.
    Exactly. There is an opportunity to design a wider tread trail-category tire that has a similar casing width to today's tires. Then it could be mounted on a wider rim and still fit in today's frames and forks without clearance issues. I'd think that would be a winner.
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  174. #574
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    Quote Originally Posted by bholwell View Post
    The sidewall of a bicycle tire does not handle vertical loads, as Mountain Cycle Shawn believes. The carcass of today's bicycle tires are so thin, it's simply not possible.
    I'm not a tire design engineer (but I am an ME), so correct me if I am wrong. I think tire shape when inflated is important. I think there is potential to design a tire with a wider tread pattern and shorter sidewalls that could be used in conjunction with a wide carbon rim. I would think this would work better than the traditional hourglass shape on a narrow aluminum rim. What do you think?
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  175. #575
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    ^ I think you're correct and I think we'll eventually see tires made for these wide rims. There are a lot of tires out there that work good with wide rims. But, they can get better. I mean what other industry has tires that are more than twice as wide as the rims?

  176. #576
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    I'll tell you I have learned so much about tires and pressure this year as a result of my fat bike. I am not saying traditional mtb's should all go fat, but there is something to be said for the performance of wide tires and rims. I am actually really excited about the potential now that wide carbon rims are a reality. It really changes the game imho.
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  177. #577
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    Quote Originally Posted by cycloxer13 View Post
    I'm not a tire design engineer (but I am an ME), so correct me if I am wrong. I think tire shape when inflated is important. I think there is potential to design a tire with a wider tread pattern and shorter sidewalls that could be used in conjunction with a wide carbon rim. I would think this would work better than the traditional hourglass shape on a narrow aluminum rim. What do you think?
    Wouldn't a shorter sidewall invite more rim strikes unless tire pressure were increased? And wouldn't that negate some of the wide rim advantages?

    Sorry for playing devils advocate, just trying to wrap my mind around what is real expectations with continuing to go wider.

  178. #578
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    I don't mean shorter as in closer to the ground. I mean shorter in that the shape of the inflated tire will be more semi-circular and less pinched in at the bead like a light bulb. This would be more like a motorcycle tire. That's what I envision.
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  179. #579
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    Quote Originally Posted by cycloxer13 View Post
    I don't mean shorter as in closer to the ground. I mean shorter in that the shape of the inflated tire will be more semi-circular and less pinched in at the bead like a light bulb. This would be more like a motorcycle tire. That's what I envision.
    Sounds heavy. There was quite recently some discussion of why MTB tires and wheels are different than motocross or dual-sport tires and wheels. I assure you all that was considered and some of it even tried since MX predates MTB.

  180. #580
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    A wide carbon rim can be made pretty freakin light - probably even lighter than tire casing rubber. Mtb tire casing shape hasn't evolved much at all. This 'shape' if you will pre-dates carbon rims as well as tubeless systems. I think there are plenty of advances yet to come with a few tweaks.

    I am not saying we should be riding a perfectly semi-circular tire as on a road motorcycle, but I do think we could get a lot closer to that and realize performance gains. In fact, the 4.6" tire on 90mm rim on my fat bike is a lot closer. I say just scale that down a bit to a summer XC version and you have a winner.
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  181. #581
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    A bike tire is not like a car or motorcycle tire that has belts to maintain a certain cross sectional shape. A bike tire will make a constant-radius arc from one bead to the other.

  182. #582
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    Quote Originally Posted by beanbag View Post
    A bike tire is not like a car or motorcycle tire that has belts to maintain a certain cross sectional shape. A bike tire will make a constant-radius arc from one bead to the other.
    Some tires don't work with wide rims because the tread cap becomes too squared when mounted on wide rims. The arc is inside.
    But.
    It's tough to discount future innovation once something like a wide rim being more readily available gives tire designers new opportunities.
    Who knows what they will come up with?

    With all the complexities of tire design and construction I feel it's incredibly unusual dumb luck that I am getting so much more performance from using tires in a way outside their original design perimeters.

  183. #583
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    Quote Originally Posted by beanbag View Post
    A bike tire will make a constant-radius arc from one bead to the other.
    Is that shape the same or different on a wide rim? The point of the wide rim is to give the tire a better shape.
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  184. #584
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    Quote Originally Posted by beanbag View Post
    A bike tire is not like a car or motorcycle tire that has belts to maintain a certain cross sectional shape. A bike tire will make a constant-radius arc from one bead to the other.
    Not exactly. Bicycle tires are definitely not like belted radial light truck or passenger tires. But they are quite similar to off-road motorcycle and non-belted bias ATV tires. The construction of a typical XC or AM bicycle tire is one body ply turned up over the beads. The turn-up is of adequate length to overlap in the center, underneath the tread. So you end up with two plies at the sidewall, and three plies underneath the tread.
    If you'd like to see a picture:Basic Tire Construction | Maxxis USA

    DH bicycle tires, off-road motorcycles tires, and non-belted bias ATV tires typically have two plies turned up over the beads, but the turn-ups are much shorter. In DH tires, the turn-ups end near the sidewall and tread junction, and in ATV tires the turn-ups are much lower.

    All of the aforementioned tires have a bias construction, meaning that the direction of the cords within the body plies lie at an angle perpendicular to the direction of rotation. This angle is important because it gives the tire strength and sidewall stability. The greater the angle (if no angle is zero, or equivalent to a radial tire) the shorter the section height and the wider the section width of the tire. So a tire with a very high bias angle will have a flatter tread arc.
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

  185. #585
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    Quote Originally Posted by cycloxer13 View Post
    Is that shape the same or different on a wide rim? The point of the wide rim is to give the tire a better shape.
    It will be a different shape. But I don't agree that it's necessarily a better shape, especially if the rim is much wider than the tire design engineer intended.
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

  186. #586
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    Blank sheet of paper. If you could match a new carbon rim to a new design tire for trail use, would you go wider than today's 'normal' 20mm rims?
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  187. #587
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    Quote Originally Posted by beanbag View Post
    I dunno, the bike industry was pretty ruthless in killing off the 26" wheel.
    Yes, but that was for a different reason entirely, imo. There's a lot of performance overlap between the 26" and 27.5" wheel, and carrying the same models in both wheel sizes doesn't make a heck of a lot of sense. But one company can't simply say rims widths under 26mm are dead, and start designing all of their tires for rims with an internal width of 35mm. They'd be missing out on a lot of sales.
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

  188. #588
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    Quote Originally Posted by cycloxer13 View Post
    Blank sheet of paper. If you could match a new carbon rim to a new design tire for trail use, would you go wider than today's 'normal' 20mm rims?
    Absolutely. Although I think today's rims are actually wider than that. Not long ago, the typical XC rim was 17 or 19mm wide internally. Stan's rims became very popular, and their first model was the 355 which was 19mm wide internally. Now the Crest is 21mm wide. And when they release the next generation rims, they'll be even wider.

    That's XC, and AM rims are even wider.

    Where will we ultimately end up? I don't know. Weight will still be a consideration, because even though carbon rims can be made lighter, wider rims are still heavier, and unless the price of carbon comes way down the majority of rims will continue to be Al. But with the weight consideration aside, from a performance standpoint I think the optimal rim width is much closer to off-road motorcycle rims (as a percentage of rim width to tire section width) than where we are currently.
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  189. #589
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    Quote Originally Posted by cycloxer13 View Post
    I'm not a tire design engineer (but I am an ME), so correct me if I am wrong. I think tire shape when inflated is important. I think there is potential to design a tire with a wider tread pattern and shorter sidewalls that could be used in conjunction with a wide carbon rim. I would think this would work better than the traditional hourglass shape on a narrow aluminum rim. What do you think?
    Yes, I agree. Doing so will result in better traction, particularly cornering performance.

    But go too far in the extreme and you'll be extending your tread arc (relocating the shoulder lugs further apart, further down the sidewall), and this will add under-tread rubber, which will add weight and rolling resistance. Not good for XC.
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  190. #590
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    I agree 100%. I can't wait to see the first 'wide rim specific' trail tire. I'd imagine you could wrap the tread a littler wider and see a performance improvement.

    My 4.6" Ground Controls are shaped a lot more like a motocross tire than a mountain bike tire. Of course they also weigh 1,500 grams each.
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  191. #591
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    Nobody remembers the michelin 2.8's and the sun doubles? Wide rims and tires have already been done. Great for straight line plowing or making up for lack of skill/correct body english.

    I think these ultra wide rims will go the way of the long travel 29r. All the intermediate riders are going to rant and rave and swear its the wave of the future. After awhile common sense will prevail and they will stilll be available but will not be dominating the market. Yes they will give you gobs of traction and be great in a straight line, but the extra weight and gyro affect will make them less nimble. Everyone wanted 29r Downhil bikes and 6" trail bikes, but how many of those do you see now?

    Like everything, there is a middle ground. I think 25-30mm wide internal width is the ticket for most trail/all mountain/Dh bikes. Save the ultra wide rims for the guys on ridgid and single speeds where you need a big huge volume tire at low pressure to make up for a lack of suspension.
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  192. #592
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    Wide Rims? Don't believe the hype...

    Wide tires also provide tons of traction in corners and frankly I like the fact that they make up for my lack of skills - which a full suspension bike also does. I do ride a rigid SS and may have different priorities than some. I'm turning 45 in a couple days and don't mind "cheating" if it keeps my face off the ground.

  193. #593
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    Well the current wide rims with normal tires do not make for tons of traction if you actually lean the bike over hard, as you roll right past those side knobs.....

    I'm not completely discounting them. Im just saying that this new trend of people who think these wide rims and the best thing since suspension forks are not looking at this from all angles.
    friends don't let friends Fred

  194. #594
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    Quote Originally Posted by Yody View Post
    Nobody remembers the michelin 2.8's and the sun doubles? Wide rims and tires have already been done. Great for straight line plowing or making up for lack of skill/correct body english.

    I think these ultra wide rims will go the way of the long travel 29r. All the intermediate riders are going to rant and rave and swear its the wave of the future. After awhile common sense will prevail and they will stilll be available but will not be dominating the market. Yes they will give you gobs of traction and be great in a straight line, but the extra weight and gyro affect will make them less nimble. Everyone wanted 29r Downhil bikes and 6" trail bikes, but how many of those do you see now?

    Like everything, there is a middle ground. I think 25-30mm wide internal width is the ticket for most trail/all mountain/Dh bikes. Save the ultra wide rims for the guys on ridgid and single speeds where you need a big huge volume tire at low pressure to make up for a lack of suspension.
    ^This. In skiing there is gear that helps intermediates do the best they ever have but holds back experts. There is gear that experts love but intermediates struggle with (I'm talking straight, stiff skis and stiff boots). Soft suspension and overly wide rims fit in the former category in the MTB world. Pros use firm suspension and rims that create a rounder tire shape. Pick the gear that works best for you and enjoy the ride. The "hype" would be believing that one thing is best for everyone and every condition.
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  195. #595
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    Quote Originally Posted by Yody View Post
    Well the current wide rims with normal tires do not make for tons of traction if you actually lean the bike over hard, as you roll right past those side knobs.....
    That's your opinion. Pick the right tire and you can lean like hell on them and the silly grin you get on your face lasts till you hit the next corner, where the silly grin gets refreshed, and it just keeps going.

  196. #596
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    video=youtube;][/video]...

  197. #597
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    We need some new tires designed specifically for wide rims. Fortunately that is doable. It's a huge opportunity for the tire manufacturers. Everyone loves throwing on a fresh set of rubbers and even the most expensive tire don't break the bank.
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  198. #598
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    Is there any consensus on whether wide rims are the way to go?

  199. #599
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    Wide Rims? Don't believe the hype...

    Quote Originally Posted by Alias530 View Post
    Is there any consensus on whether wide rims are the way to go?
    I don't think there is even a consensus on what the word wide means.
    It's just a flesh wound!

  200. #600
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    My dilemma is--is going from 24->30mm internal going to be worth the ~9% weight penalty or should I stick with 24mm for trail riding?

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