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  1. #1
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    Tubeless Fat Bike Rim Width

    Hey fat riders!

    I have a 'hypothetical' question / poll of sorts. If one were tinkering with an idea for a tubeless-specific fat bike rim during their spare time, what rim width would you guys hope to see as a first offering? From lurking here in the forums I know there are people all over the map on this but I guess the question could be re-stated as 'What would you say is the most versatile width for a fat bike rim?'

    Look forward to any thoughts and discussion, thanks everyone.

    Chris

  2. #2
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    From a singletrack/dirt point of view im going with the marge lite width of 65mm.

    Most versatile would have to be 80mm at the halfway point between flotation of clownshoes and speed/weight of marge lites.

    I dont know what the puncture per ride ratio is between riding snow and riding dirt but would imaging small punctures and pinch flats are more common on hard ground.
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  3. #3
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    For me as a non-snow rider desert dweller it would be a marge width.
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  4. #4
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    70 mm seems about right for me.

  5. #5
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    As a non-snow desert dweller who rides a lot of sandy arroyos - I would love to see some 100's.

    However, if a mfg wanted to maximize their sales - probably 80mm. That seems to be the best compromise between float and fit. For now.
    This isn't a "you're doing it wrong" topic.

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  6. #6
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    100mm is the only width for me.

  7. #7
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    100 is my personal choice but if I had to guess what the majority would say it would be 80.

  8. #8
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    Marge width or ever so slightly wider.

  9. #9
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    If your goal is commercial success then choose a rim that works for the majority of fatbikes - 60mm - 80mm. If you go with 100mm rims they'll appeal to Moonlander owners and anyone who has a fatty that can take extra wide 5" rubber.

    I'd probably start with 65mm rims which will work for a wide audience and then go to 80mm and then lastly 100m if everything is looking good.
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  10. #10
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    Hey guys, thanks for the responses. The main reason for the poll is that I'm not a rim manufacturer myself, so there is a pretty large barrier of entry to get in to something. Pretty much limits this to a single rim for starters, which makes it important to get the size right.

    Does a robust tubeless set up appeal to you? I'm not necessarily looking to do something lighter but rather a bombproof set up for when you're out away from civilization.

    Thanks, any more thoughts, opinions, whatever are greatly appreciated!

    Chris

  11. #11
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    Heavier/bombproof wheels don't interest me. I'd lean more toward lighter in tubeless for better trail performance for my personal use.

    And I'd have to say that you would probably have an uphill battle trying to market a heavy rim as I think that the market is pretty well covered in that area.

    Surly's original 65 mm Large Marge (double wall) is well established. And chopper bike wheels are easy to get in 2.5, 3, and 4 inch widths for as little as $50. They're double wall, so heavy but no doubt durable. Drilling may be an issue though as many are drilled for 36 spoke hubs. But if you're looking for reliable, 36 may be the way to go...

    For example Wheel/Tire/Tube/Hub/Rim : Rims Only - Cycles U.S. LLC/Choppers U.S.

  12. #12
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    Quote Originally Posted by JoeG View Post
    Heavier/bombproof wheels don't interest me. I'd lean more toward lighter in tubeless for better trail performance for my personal use.
    +1 - Given how much abuse Surly's single wall cut out rims are taking without any major problems I think you'd be hard pressed to get people to buy heavier rims.
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  13. #13
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    Quote Originally Posted by JoeG View Post
    Heavier/bombproof wheels don't interest me. I'd lean more toward lighter in tubeless for better trail performance for my personal use.
    This.

  14. #14
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    Now keep in mind I never said they would be heavier than current stuff... just not necessarily lighter.

    The idea basically revolves around using a bead clamp ring (sort of like what an off-road vehicle with low tire pressures might use) so that instead of relying on air pressure to keep the bead seated it is physically secured in place. Theoretically I could use sealant to get everything airtight and not have to worry about burping or peeling the tire off the rim as well as having some puncture protection (as much as a sealant would provide anyway).

    At this point I envision a single wall rim with no cutouts. Certainly sealing up the system would be easier without them but the weight savings (as others have proven) could be significant with some thoughtfully placed holes.

    I hope a bit more information might spark further discussion, let me know what you guys think and thanks again!

    Chris

  15. #15
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    I've thought a little bit myself about a bead clamp system for making a tubeless tire that is burp proof. I couldn't really think of a way to make it work and still be light enough to compete with regular rims. If you got an idea, then go for it!

  16. #16
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    Quote Originally Posted by singltraker View Post
    The idea basically revolves around using a bead clamp ring (sort of like what an off-road vehicle with low tire pressures might use) so that instead of relying on air pressure to keep the bead seated it is physically secured in place. Theoretically I could use sealant to get everything airtight and not have to worry about burping or peeling the tire off the rim as well as having some puncture protection (as much as a sealant would provide anyway).

    At this point I envision a single wall rim with no cutouts. Certainly sealing up the system would be easier without them but the weight savings (as others have proven) could be significant with some thoughtfully placed holes.
    Bead clamp ring? Sounds heavy unless you are using carbon fiber with titanium bolts, and still probably probably heavier than current rims. And more complex.

    Not sure why one would want to complicate a rim.... What we have now works great. I've been running tubeless for years without any issues. No burping. No peeling. No problems.

    If you want a single wall rim with no cutouts to make it easier to seal, then what about the spoke nipples? A little sealant won't seal around those.

    I do, on the other hand, like the idea of thinking outside the box, but I really think you'll have to make something lighter or cheaper to make it work here.

  17. #17
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    Quote Originally Posted by singltraker View Post
    Now keep in mind I never said they would be heavier than current stuff... just not necessarily lighter.

    The idea basically revolves around using a bead clamp ring

    I hope a bit more information might spark further discussion, let me know what you guys think and thanks again!

    Chris
    Now this is a different question. And I think that getting the necessary strength w/o excessive weight will be a challenge using a bead clamp - especially as you would need to clamp both beads to prevent burping.
    I've been working on a DIY approach based on an inflatable beadlock. Beadlocks for tubeless. The Staun system for 4wd and the Nuetech TuBliss for m/c are available commercially. They both use the equivalent of an inner tire with a "high" pressure tube to lock the outer tire bead in place and allow it to run whatever pressure w/o risk of losing the bead seal. This would also have the advantage of being independent of the rim, and allow whatever cutouts you want - sealing them just like we seal them now with tubes or ghetto tubeless.

    Here's the Nuetech system: https://www.brapoffroad.com/images/p...ch-Flyer-1.gif I tried to link the pic - but the forum upgrade is not apparently working that way (sigh)
    Tubeless Fat Bike Rim Width-nuetech-flyer-1.gif

    I'm using a 26x1.25 road slick cut down the middle, with a strip of material (web strap at first, trying sailcloth now) sew into the gap.
    Tubeless Fat Bike Rim Width-img_1415s.jpg
    This strip needs to be sized to match the rim width. 3" between the tire halves works for 100mm, 2" for 80mm or 65mm. Nuetech uses a "normal" m/c rimlock to hold the air passage for the main tire, deflecting the inner tube around the stem. I'm using a bit of tubing spiraling around the innertube and exiting a hole in the strip. http://gallery.mtbr.com/data/mtbr/50.../IMG_1416s.JPG
    Tubeless Fat Bike Rim Width-img_1416s.jpg
    Attached Thumbnails Attached Thumbnails Tubeless Fat Bike Rim Width-659044d1323624776-beadlocks-tubeless-img_1744s.jpg  

    This isn't a "you're doing it wrong" topic.

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  18. #18
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    I like innovation as much as the next guy, but I think you are searching for a solution to a problem that doesn't exist. Who is having reliability or burping issues with fat tubeless? If done right, ghetto tubeless is bombproof on these bikes.
    Whatever floats your bike, dude

  19. #19
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    Quote Originally Posted by Dustin Mustangs View Post
    I like innovation as much as the next guy, but I think you are searching for a solution to a problem that doesn't exist. Who is having reliability or burping issues with fat tubeless? If done right, ghetto tubeless is bombproof on these bikes.
    I was under the impression that tubeless on a fat bike was tough to achieve, I've seen some pretty elaborate DIY setups to help support the beads, etc. Maybe I'm wrong? Certainly if the fat bikers who want tubeless are just going ghetto with no problems than this idea doesn't make much sense. I'm not interested in pursuing a solution to a problem that doesn't exist for sure!

    FYI, I've got a model drawn for a single wall rim that seems to have reasonable wall thicknesses, etc. that comes in at 1365g with steel hardware. According to the Surly website the Rolling Darryl with Toob would be 1310 - 1480g depending on whether you want cutouts or not. I know the first comment will be about how their are alternatives to the heavy Surly tubes and how I haven't included rim strips, rim tape, sealant, etc but I'm just trying to give a rough picture for now.

    Thanks everyone for your input, I'd love to hear more if anyone has anything to add. Sounds like maybe I'm off base on the demand for a solid tubeless rim but we'll see!

    Chris

  20. #20
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    With the retainer grooves on Surly rims it's less critical - but when the pressure gets really low - it's still an issue, I think. Do you need to run it that low when tubeless? Don't know.

    I'll continue with the project - it is definitely bombproof, and is also a run-flat solution. I recall all the weight based arguments re:tubeless, but performance is what makes it good.

    I note that I tried ghetto tubeless back in early 29er days - and had a few rock/twist related burps. Going to StanRims mostly cured that, but it still happens on those trails occasionally. Fatties have much more grip, and I think they would have issues with this in these areas.
    This isn't a "you're doing it wrong" topic.

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  21. #21
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    It is a pain to set up. No two ways around that. But once you get it done right there is no reliability concern imo, esp when it comes to the bead. At times I run pressures low enough to get double wrinkles in my sidewalls when loaded in a static state. No pressure or sealant loss ever. No Burping. No spinning on the rim. No problems at all. Again, this is once I did it right because I did initially have issues with the bead leaking. The trick is to build up the shelf with a couple layers of tape or a split tube to the point where the bead literally pops onto the rim when inflated.

    As a fat tubeless connoisseur, the only thing I could see myself buying along these lines is some type of a rim strip system that is lighter and easier to setup than the current ghetto methods. Bonus points if you can air it up without a compressor although I have doubts that is (repeatably) possible despite some claiming it is.
    Whatever floats your bike, dude

  22. #22
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    I've run Stan's tubeless on my regular MTBs for many years. I'm new to both fatbikes and fat tubeless, but I don't think that burping will be much of a problem in the fatbike arena. Why? Because 65+ mm rims are wide enough that the tire's contact patch will stay between the rim's beads. The article below explains this concept of tubeless tires burping really well:

    Tech Tuesday

    So I think that 3.7-4.0 inch tires on 65+ mm rims will have few issues with burping. But BFLs on 40 mm rims would likely have burping issues. Only time will tell, though.

    Edit:
    As a fat tubeless connoisseur, the only thing I could see myself buying along these lines is some type of a rim strip system that is lighter and easier to setup than the current ghetto methods. Bonus points if you can air it up without a compressor although I have doubts that is (repeatably) possible despite some claiming it is.
    +1.

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