Changing Fork Offset, worth it or is it BS?- Mtbr.com
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  1. #1
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    Changing Fork Offset, worth it or is it BS?

    Okay, so I've been doing my research, looking at the Ibis and Transition marketing, reading all the blogs on reduced offsets in big wheeled bikes. Not that I discount their theories, but I kinda wonder if it's just smoke and mirrors.

    I just got a Trek Full Stache 29+, the Pike fork has a 51mm offset running at 130mm travel. I plan on getting a longer air shaft to run 140 or 150mm. The Frame also has a flip chip, currently set in low.

    As the bike sits, the steering is heavy, even for a 29+, which causes the front end to push and skitter a bit more than I like; getting forward helps.

    I can get a reduced offset upper assembly with a 46mm offset, it'll run a few hundred simoleans, I'd swap air shafts at the same time.

    Slacking out the HTA will likely worsen the heavy steering and "pushing", but I can compensate somewhat by putting the flip chip in the high position; bb is low in stock setup, so I don't worry about the bb being to elevated.

    I don't mind expending the time and dollars to experiment, but is it even worth the effort?

    Ready, set, discuss!

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    I haven't done A/B comparisons myself but this article did and seems to confirm that there is something to be gain, but there's no free lunch.

    https://www.bikeradar.com/us/mtb/gea...eriment-45343/

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    Yeah, I read that article. I talked a buddy at my LBS, he's a long time DH guy, told me he'd played with fork offset a ton back in he day and all he noticed was a similarity to changing STA. He thought the change in offset could help minimize the effects of slacking HTA from an increase in travel.

    Quote Originally Posted by TheBaldBlur View Post
    I haven't done A/B comparisons myself but this article did and seems to confirm that there is something to be gain, but there's no free lunch.

    https://www.bikeradar.com/us/mtb/gea...eriment-45343/

  4. #4
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    Here is an online tool to help calculate trail. Bicycle Trail Calculator | yojimg.net
    Longer trail numbers tend to increase stability and shorter increases steering quickness.

    Everyone has there own preferences depending on riding terrain, bike geometry, riding style. i prefer the longer offset on 29ers so that they handle quicker in tight singletrack.

    Lots of other variables affect steering feel, like bar and stem width, wheel diameter, tire design etc.

    Good Luck

    mike

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    Help me out, I seem to have things backwards.

    So increasing offset increases handling quickness?

    In other words, going from a 51mm to a 46mm offset will worsen my problems?

    Quote Originally Posted by senor_mikey View Post
    Here is an online tool to help calculate trail. Bicycle Trail Calculator | yojimg.net
    Longer trail numbers tend to increase stability and shorter increases steering quickness.

    Everyone has there own preferences depending on riding terrain, bike geometry, riding style. i prefer the longer offset on 29ers so that they handle quicker in tight singletrack.

    Lots of other variables affect steering feel, like bar and stem width, wheel diameter, tire design etc.

    Good Luck

    mike

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    yes

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    Quote Originally Posted by Nurse Ben View Post
    As the bike sits, the steering is heavy, even for a 29+, which causes the front end to push and skitter a bit more than I like; getting forward helps.
    Long modern geo bikes require you ride the bike up front a lot more to weight that front wheel or the bike won't steer properly. If you ride it like a shorter bike you'll be too far towards the rear wheel.
    Safe riding,

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  8. #8
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    I posted this in the Ripmo thread a couple of weeks ago on the 51 vs 44 offset question. I plan to pick up a Ripmo at some point and plan to run my 51 offset Lyrik from my Hightower on it....

    Mike Kazimer from Pinkbike actually swapped between 44 and 51 offset forks when he reviewed the Sentinel ( https://www.pinkbike.com/news/transi...view-2017.html and he didn't find any statistical difference between the two offsets when he timed his runs at Whistler. Sounds like he preferred the feel of the 44 though...

    I've been answering all sorts of questions about offset lately, many from riders who are worried about getting left behind by some sort of new “standard.” Should you rush out and buy a fork with the least amount of offset you can find? Well, no. The amount of offset does make a noticeable handling difference, but it's not as cut and dry as saying that X amount of offset is bad and Y amount of offset is good – there's more to it than that, and installing a fork with the least amount of offset possible isn't going to automatically turn your bike into a magical shred sled.

    I spent a day in the bike park switching back and forth between two Fox 36 forks, the one that came on the Sentinel, which has 44mm of offset, and one with 51mm of offset, which is what the majority of 29ers are currently spec'd with. I started off by taking three laps on the stock fork, and then made the switch to the fork with 51mm of offset. The difference is very noticeable – the increased offset felt more like what I'm used to, and the bike felt livelier, but it was also easier to oversteer and wash out the front wheel – the feeling of unlimited front wheel traction that the 44mm offset fork delivered wasn't there anymore.

    I timed all of my runs, but the numbers didn't end up indicating any statistically significant difference between the two offsets; I felt like I was able to adapt my riding style fairly quickly to both forks. After swapping back and forth between the two offsets it was clear that there are benefits to the stock, reduced offset fork on the Sentinel – namely better front wheel grip and more stability – but the bike works just fine with a 'regular' 51mm offset fork as well.

  9. #9
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    Yup, stay forward, just like skis, figured that out a while back.

    In response to MSH: So it might help, just not in the way I'm thinking, so I try it and if I like it, therefore I do.

    I was thinking of swapping in my Pike 27+ 130mm fork from a Hendrix, which might give me an idea of how 46mm offset feels... assuming the fork will clear 29+.

    Quote Originally Posted by vikb View Post
    Long modern geo bikes require you ride the bike up front a lot more to weight that front wheel or the bike won't steer properly. If you ride it like a shorter bike you'll be too far towards the rear wheel.

  10. #10
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    Watch a video of a pro DH rider cornering - long front end means you've gotta get forward to get traction. No free lunch.

    The "longer is always better" (Pole bikes, wtf) thing that's been going on for the last few years is pretty silly, IMO. Longer is better for some things, for some riders. It's horrible if you ride twisty flat midwest singletrack or almost anything else that isn't ultra fast/steep, but that hasn't stopped people from buying bikes with 800mm+ front centers and 1250mm+ wheelbases, slapping on 30mm stems, and hauling those boats around their local trails.

    In a way, the lower offset mini-trend is good - someone realized this. If you want a lot of steering trail, but you *don't* want a super long front center/wheelbase, you have two choices - reduce the fork offset (possibly in combination with a steeper HTA) or else use a longer stem/shorter toptube.

    Since stems longer than 50mm are basically anathema these days, the only way to go for these companies is the reduced offset route. But it's better than just leaving the bikes too long, at least.

    -Walt

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    Hey Walt, thanks for chiming in.

    When you look at the geo for a bike like the Full Stache, do you see any benefit to changing offset? It's not that long of a bike, I'm a decent rider technically, just curious as I start playing with the bike whether a reduced offset is worth considering.

    Quote Originally Posted by Walt View Post
    Watch a video of a pro DH rider cornering - long front end means you've gotta get forward to get traction. No free lunch.

    The "longer is always better" (Pole bikes, wtf) thing that's been going on for the last few years is pretty silly, IMO. Longer is better for some things, for some riders. It's horrible if you ride twisty flat midwest singletrack or almost anything else that isn't ultra fast/steep, but that hasn't stopped people from buying bikes with 800mm+ front centers and 1250mm+ wheelbases, slapping on 30mm stems, and hauling those boats around their local trails.

    In a way, the lower offset mini-trend is good - someone realized this. If you want a lot of steering trail, but you *don't* want a super long front center/wheelbase, you have two choices - reduce the fork offset (possibly in combination with a steeper HTA) or else use a longer stem/shorter toptube.

    Since stems longer than 50mm are basically anathema these days, the only way to go for these companies is the reduced offset route. But it's better than just leaving the bikes too long, at least.

    -Walt

  12. #12
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    Quote Originally Posted by Nurse Ben View Post
    Help me out, I seem to have things backwards.

    So increasing offset increases handling quickness?

    In other words, going from a 51mm to a 46mm offset will worsen my problems?
    When you increase offset the trail is shorted which makes the bike turn quicker. So the smaller offset fork will make the bike more stable.

    mike

  13. #13
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    Quote Originally Posted by Nurse Ben View Post
    Hey Walt, thanks for chiming in.

    When you look at the geo for a bike like the Full Stache, do you see any benefit to changing offset? It's not that long of a bike, I'm a decent rider technically, just curious as I start playing with the bike whether a reduced offset is worth considering.
    I think (didn't read the article) that the guy who "tested" them head to head said it pretty well - this is more of a matter of preference than anything. If you want more steering trail and a very slightly shorter front center, it's worth a try.

    Remember, though, that the minimum amount of steering trail (absent other changes) you can perceive is in the 5-7mm range anyway. It's going to be a subtle change, not a dramatic one. Likewise the front center isn't going to shrink that much - probably below the threshold of detectability for most people. Put them together and you'll notice some slight changes, though.

    I'm rambling. I wouldn't go spend $800 on a fork to test this theory unless you have a lot of extra money laying around. If you want to see what a shorter front center feels like, riding the same bike a size down (will require a longer stem with some rise and/or spacers to maintain consistent contact points, but that's fine) would be a better experiment.

    IMO the Full Stache is a "long" bike, btw. Trek doesn't list a front center number but we can roughly extrapolate from the wheelbase and chainstay length numbers. I estimate a front center (for the larg/19.5" which is roughly what would "fit" me) in the ballpark of 775mm. I tend to like a front center around 700mm for XC and 25-40mm longer for DH stupidity. Make of that what you will.

    -Walt

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    Ok, got it, so it might feel shorter, but not quicker in the steering response. It’s about $300 give or take to try a reduced offset crown. I’m changing air shafts, so it might be worth it. Also got the option of flipping the chip.

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    Quote Originally Posted by Nurse Ben View Post
    Ok, got it, so it might feel shorter, but not quicker in the steering response. It’s about $300 give or take to try a reduced offset crown. I’m changing air shafts, so it might be worth it. Also got the option of flipping the chip.
    Yes, steering response will be a bit slower due to higher trail number - that will be the main difference. I don't think you'll notice the shorter front center much - it's only 1/4".

    I actually have a couple of 44mm offset Fox 32s that fit 29+ (barely) from 3 or 4 years ago that I have stashed away for myself for use for future hardtails. Sounds like maybe I wasted my time holding onto them if this lower-offset thing takes off.

    At the very least it would be nice to have a choice again. If I ran the circus I'd want something like 51mm (don't make all the current bike obsolete) and 38mm or so (the old 26" standard), so there's enough of a difference to actually do distinct designs for different riders/purposes. Probably a pipe dream, though.

    Let us know what you think when you try it!

    -Walt

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    what Walt said.

    and it's neither smokenmirrors nor uncommon in the broader 2 wheeled community. motocross/enduro (as in motorcycle) play around with fork offset quite a bit to tune in handling, sometimes for particular race courses.

  17. #17
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    I started with a stock 130/130 Full Stache in the 'low' Mino Link position. Front end felt awkward -- slow, heavy, not confidence inspiring.

    Flipped the chip to the high position and extended the fork to 140mm. Feels great to me now. More or less invisible.

  18. #18
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    It's great to read Walt's counterpoint to the current trend of super long front centers. I'm one of those flat midwest riders, so I like a bit of sharpness in my handling.

    Several years ago, I swapped the crown on my old Reba from the first gen 29er offset (38mm) to the G2 offset (51mm), hoping to get quicker handling. Honestly, I couldn't tell much difference. I'm guessing the reduced trail was offset by the increased wheelbase. Or maybe I'm just not that sensitive.
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  19. #19
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    So Walt, I'm learning as I go, but in regards to front center, using bikes I know well:

    Full Stache = 77.8
    Hendrix = 76.2
    Fatillac = 74.29
    Wozo = 73.10
    Atlas = 66.7

    All frames were large, other than the Wozo. I briefly rode a medium Atlas.

    So the Atlas was a fun bike for me, I ran it a little taller and in the low setting, so I suspect it was closer to 700mm which you call an XC bike. It definitely climbed well, but tech descents and rowdy riding were not it's forte.

    The Full Stache (29+), Hendrix (27+), and Fatillac (27+/Bfat) are a fairly close, but the ride feel is very different between the three.

    Of the FS bikes, the Full Stache feels the longest by far, Fatillac feels the shortest, the Hendrix just feels small; I felt like I could have ridden an XL in the Fatillac and Hendrix except for standover.

    The Wozo feels as long or longer than any of these bikes and it's a medium frame with the shortest FTC other than the Atlas; I had a large and even with the shortest stem it was waaay to long for me to feel comfortable riding except when pointed downhill.

    I know there's more to this geo thing, hence my questions.

    Given a choice of bikes from this herd, I feel the most comfortable on the Full Stache and the Wozo.

    Thoughts?

    Quote Originally Posted by Walt View Post
    IMO the Full Stache is a "long" bike, btw. Trek doesn't list a front center number but we can roughly extrapolate from the wheelbase and chainstay length numbers. I estimate a front center (for the larg/19.5" which is roughly what would "fit" me) in the ballpark of 775mm. I tend to like a front center around 700mm for XC and 25-40mm longer for DH stupidity. Make of that what you will.

    -Walt

  20. #20
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    I did a direct swap of a 44mm offset Marzochi to a 51mm offset X-fusion Trace several years ago. HTA on the bike was 68. I didn't make the change for the increased offset, just wanted a stiffer fork.

    The only difference I noticed was that I was that I was picking slightly bad lines for the first 15 minutes or so of riding - oversteering and / or overcorrecting. It was very noticable. I didn't particularly care for that, but by the end of the ride and going forward, I adjusted to the change, and the bike felt completely normal. Hard to say which I would prefer without doing some back to back testing. But if I had to pick, it would be the shorter offset. I don't like really wide bars, and therefore feel my steering response is more than enough with a 44mm offset.

  21. #21
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    Sorry, I don't know what your question is. Maybe I missed something? Comparing the front centers of totally different bikes won't tell you a whole lot, just because there are so many confounding variables. Riding a size up or down (most bikes use the same chainstay length and bb height between sizes) and carefully keeping your contact points the same is going to be the only way to isolate the effect if you really want to geek out.

    -Walt

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    I read somewhere that a man with two watches never knows the time.

  23. #23
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    Quote Originally Posted by 1spd1way View Post
    I read somewhere that a man with two watches never knows the time.

    Possible. But the guy that wrote that was texting while driving, sooooo....

  24. #24
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    Not really a question, more me trying to understand geometry variables.

    I suppose I need to ask for my next birthday present to be "build a frame with Walt". Can we do a gear drive hardtail with short chainstays and 29+/Bfat?

    Seriously, I ask a lot of questions, it's annoying, but it's not me, it's the ADHD speaking

    Now that I have the Stache riding decent; ie about as close to the feel that I like as I think that I can get, I'm gonna spring for the offset uppers.

    Watches, I don't need no sticking watches! Do people still wear watches?

    Quote Originally Posted by Walt View Post
    Sorry, I don't know what your question is. Maybe I missed something? Comparing the front centers of totally different bikes won't tell you a whole lot, just because there are so many confounding variables. Riding a size up or down (most bikes use the same chainstay length and bb height between sizes) and carefully keeping your contact points the same is going to be the only way to isolate the effect if you really want to geek out.

    -Walt

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    Nurse, I was actually sending you PM about these, when I saw you have made the thread. We share the same experience with the Fatillac also, but that is another story.


    Anyway, the short offset fork thing like on the Sentinel, I can share the experience some with. The Transiton Sentinel, that I have been riding for a short time, not been able to get the suspension all the way I want. But what I am expereincing, is that the bike is the most confidence expiring bike ever ridden, not only dowh hill but also uphill (first bike that I have been able to run completely without climb switch, weighing 260lbs).

    What they have done to make these bike you need to read up on the Transiton site, but what I am experiencing, is that it has been carefully thought through in every aspect. I can say it will take twisty trails and climb like you can only dream of.

    So Nurse, only to take whatever bike and put offset fork on it, would not be the necessary make it good. I think it needs to be a part of a total design, a complete frame design throughout.
    The company Transition have been, if I understand this correctly, developing the concept of Speed Balance Control over a couple of years. That developing has been done by riders, given the freedom to change whatever they wanted. So offset fork was only one of the elements in the design.

    Here is something from the interview Transition (and I can really say I have experienced some of what is said)
    "What would you most expect riders to notice with SBG?

    With SBG you will notice increased front wheel grip, calmer steering, a bigger window to shift your weight around and an overall more confident safer feeling bike. Tight uphill switchbacks will feel easier with less front wheel push, you will have more control on difficult trail surfaces and off camber sections, more confidence when you start to drift or break traction, you will feel more comfortable on steep lines, and you will feel more stable at high speeds There is more low speed control but more high speed stability as well. The bike benefits from deliberate rider inputs and you don't have to spend as much energy making micro corrections. The handling differences on an SBG bike are very noticeable, but it gets really interesting when you go back to a non SBG bike. The non SBG bike will feel nervous and twitchy at all all speeds and it will feel like you need to make more inputs to keep the bike stable and tracking where you want it to go. The SBG bike is more planted and predictable and allows the rider to push the bike harder with less effort and feel safer doing it."

    "Are there any traits you might have appreciated in the previous iterations of the bikes that may be lost with SBG? I'm thinking specifically about the fact that I find it harder to get longer bikes up on the rear wheel.

    We honestly don't feel we have lost any of the characteristics of our old models. In fact, it's quite the opposite. We feel that SBG has allowed us to keep the playful agile nature of our previous bikes while simultaneously improving their stability and control. Some of the high speed handling traits and weight balance benefits of an SBG bike could have been achieved with increased chainstay length, however they would have come at the expense of low speed agility and general playfulness. With SBG you get to have a playful bike that is still stable and planted when you need it to be. That is part of where the SBG name comes from. It's balanced at all speeds. "

    "Other companies have played with geometries like this for some time, but maybe without the change in fork offset. Could you be accused of acting in a way that suggests you have invented something that Mondraker and others are already doing? That may be the part of this (rather than the acronym) that seems counter to your anti-corporate, corporate ethos.

    It feels like every new bike release for the past several years has touted that it's longer and often slacker. While it is true that our new SBG models are longer and slacker than our previous versions; that is only part of the SBG concept. Early on I thought it would have been funny to promote our new bikes as shorter (in reference to the fork offset) and steeper (in reference to the seat tube angle) than our previous models. You know... poking fun at those ubiquitous buzz words by going the other direction. Some of the European brands (Mondraker being especially early and notable) have pushed really extreme reach numbers for years, but what we are doing is different. The fork offset change is the biggest component of SBG and those brands offering huge reach numbers aren't doing that. I think they have a different way of looking at how a bike should handle. I won't say they are wrong, but I think we are achieving something better and more balanced with our direction. In our SBG bikes, the increase in reach is actually pretty modest, but it's necessary to keep the sizing and handling correct. We aren't just trying to make bigger bikes, we are trying to make better bikes. I think it's a lot different than just stretching the bike out with longer and longer reach."

  26. #26
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    Transition just dramatically increased the trail number (slacker HTA and lower offset) while at the same time moving the rider forward (when seated).

    There's nothing magic about it - the bike will do better when climbing seated (albeit for most people with a small loss in power as they sit further forward than optimal). It will descend well on steep/rough/fast. Not a big difference between this and other long/low/slack bikes, despite what Transition is claiming.

    But there's no free lunch. On flat/twisty stuff, this bike is still a LOOONG bike. It's longer than their previous models, in fact. It will require a lot of work to wrestle through corners and the front wheel is still way out in front - great for steep/fast, not great for tight and twisty.

    A lot of what they wanted to do here could have been accomplished by decreasing the reach/front center and using a longer stem. But they're apparently not brave enough to buck that industry trend, so while it's admirable that they tried to control the wheelbase a little bit - it's still a crazy long bike, just like all the other crazy long bikes that are the popular thing right now. If you like long, you'll like it. If you like quicker steering for tighter/twistier terrain, it'll be a handful.

    -Walt

  27. #27
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    Quote Originally Posted by Nurse Ben View Post
    Not really a question, more me trying to understand geometry variables.

    I suppose I need to ask for my next birthday present to be "build a frame with Walt". Can we do a gear drive hardtail with short chainstays and 29+/Bfat?

    Seriously, I ask a lot of questions, it's annoying, but it's not me, it's the ADHD speaking

    Now that I have the Stache riding decent; ie about as close to the feel that I like as I think that I can get, I'm gonna spring for the offset uppers.

    Watches, I don't need no sticking watches! Do people still wear watches?
    My experience with steering geo. and trail has been that it doesn't matter much until you exceed a steering trail threshold - which, I believe, is different for different bikes due to all the steering geo. variables. 51mm, 47mm, 39mm offset... it depends on the bike. The "problem" (if you want to call it that) is that you would be hard-pressed to find a fork that only changes in the offset without changing some other steering geometry variable(s) at the same time. That's why 4mm here or there doesn't matter much - unless your trail figure is getting "really high" - whatever that is (120mm? Walt?) - or "really low" - whatever that is (<80mm?).

    -F
    It's never easier - you just go faster.

  28. #28
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    I'll agree with the crazy long bikes and handling, there is a huge difference between how the Full Stache and Fatillac handle, not in a bad way, just a distinct difference that would have it's fans and detractors based on needs.

    No free lunch!

    Thanks Walt,

    Quote Originally Posted by Walt View Post
    Transition just dramatically increased the trail number (slacker HTA and lower offset) while at the same time moving the rider forward (when seated).

    There's nothing magic about it - the bike will do better when climbing seated (albeit for most people with a small loss in power as they sit further forward than optimal). It will descend well on steep/rough/fast. Not a big difference between this and other long/low/slack bikes, despite what Transition is claiming.

    But there's no free lunch. On flat/twisty stuff, this bike is still a LOOONG bike. It's longer than their previous models, in fact. It will require a lot of work to wrestle through corners and the front wheel is still way out in front - great for steep/fast, not great for tight and twisty.

    A lot of what they wanted to do here could have been accomplished by decreasing the reach/front center and using a longer stem. But they're apparently not brave enough to buck that industry trend, so while it's admirable that they tried to control the wheelbase a little bit - it's still a crazy long bike, just like all the other crazy long bikes that are the popular thing right now. If you like long, you'll like it. If you like quicker steering for tighter/twistier terrain, it'll be a handful.

    -Walt

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    I'm not a suspension or geometry expert but I do love to tinker and will add my experience for you to consider.

    So I was running 27+ on my Riot pretty much all the time. Only used 29's now and then. I wanted to try a different fork so sold my Pike and I bought a normal 27.5 Fox 36 160mm with 44mm offset because it had ample room for the 2.8's I was rocking. I had about 6 rides on that set up and can definitely say that the shorter offset was way better for the B+ tire. Previously, at high speeds and in flat corners I always felt like I had to muscle my turns around with the other 29 forks that I ran. Similarly, at low speeds I felt like the steering was too twitchy and couldn't get the precision I wanted. The 44mm offset fork alleviated all of that for me on the same 27.5x2.8 i30 wheels that I had always been running. Like a whole new bike. This should be no surprise as the 2.8s aren't that much taller than the rest of the 27.5 tires out there and the 44 offset is much more appropriate.

    Then for whatever reason I was missing the ability to run 29's... and as we all know once that scratch is there it has to be itched.

    So I built a new 29 wheelset and bought a set of 29 lowers for the 36 and a 150 air spring shaft and converted the fork over to a short offset 29. I only have two rides on it with 29x2.6 Rekons but I can perceive no appreciable negative to the setup. If anything I think the handling is better with the 29's than with the 27's. It's definitely better than the 51mm offset on my Pike. Its better on the climbs, I don't wander at all, more precise in the flats and tight woods, I can easily and accurately pick my lines and also is super stable on the DH's as advertised.

    It's early on though. I've only had two muddy rides on the 29's. To be fair, lots of variables changed as well. Pike was 15x100 w/51mm offset on a size small Riot frame and a noodly WTB i23 wheelset and Butcher 2.3 with control casing. New setup is a Fox 36 boost w/44mm offset on a size medium Riot with Nextie carbon i32's and Rekon 2.6 with EXO casing. The 27.5 i30 wheels, DHF 3C 2.8, and Rekon DC 2.8 rear tires, cockpit, brakes and drivetrain where all reused frame to frame.

    Regardless, this setup is working very well for me so far and I have no regrets with this setup. Again, take all that for what it is, just my initial positive experience with a reduction in offset.
    2017 Canfield Riot

  30. #30
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    Quote Originally Posted by Fleas View Post
    That's why 4mm here or there doesn't matter much - unless your trail figure is getting "really high" - whatever that is (120mm? Walt?) - or "really low" - whatever that is (<80mm?).
    -F
    This is a good point. As the trail number gets higher, the ability to perceive a small change is going to drop. A track bike (~30mm trail) will ride pretty noticeably differently with a 5mm change in trail. A DH bike at 150mm trail, not so much.

    For general reference for those who are curious, here's a general trail number guide:
    -30mm or so - track bike
    -50-60mm - traditional road bike
    -65-75mm - gravel or CX bike
    -75-85mm - old school (80s, 90s) XC bike
    -85-100mm - modern XC/race bike
    -100-130mm - modern XC/trail bike
    -130mm+ - freeride/DH

    Now, you can find bikes with trail number that don't fit those categories, of course, but this encompasses 95% of what's out there.

    In general, the rougher the surface and the more you want the bike to hold a line on chunk, the higher the trail number. The smoother the surface and the less you need to worry about inconveniently placed 6" cobbles, the lower. In essence, you want the bike to do what you want it to, but not what the inconsistencies of the terrain are trying to make it do - and the trail number is how you balance out those 2 needs. High trail makes it harder for you to make the bike steer, but it also makes it better at holding a line.

    -Walt

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    I have the full respect for frame designers and their thoughts. Of course I cannot argue against that a short bike will in general turn quicker than a long wheel bike, but that depends on a few things also. And there are trade offs with a short bike.
    I will just talk for myself and my experience. I am 6.3 tall and weighs 260-265 rider, so you can imagine the weight shifting going on when I am trying (just in my head though) to hold up speed on different trails, and to climb technical parts. Not to forgive my bad skills, but I think it is much harder to shift weight on a short frame design then a long. For me a short wheel base bike like Lenz Fatillac was just more demanding to ride then a longer wheelbase bike like the Transition Sentinel.
    I asked myself, what is suitable for me, in my terrain, what gives me more smiles per miles? Yes the Fatillac would be really fun playing around with, doing the stuff it is designed for, but also scaring doing other things, like fast descending trails. So for me I choose the confidence inspiring bike design like the Sentinel.
    Do I go faster or slower climbing and descending with the all too long bike? Does it feel too slow in twisty terrain? Do I feel the all too long wheelbase dragging me? I just do no timing on my rides at all, but I compare my speed between myself and the other riders going along. It is no doubt that the Sentinel is by far the fastest bike for me. Both up- and downhill.
    So my conclusion is that it might be not possible to generalize what bike design is doing best for you. We are not similar in size, weight, skills and we have not at all the same trails.

    Quote Originally Posted by Walt View Post
    Transition just dramatically increased the trail number (slacker HTA and lower offset) while at the same time moving the rider forward (when seated).

    There's nothing magic about it - the bike will do better when climbing seated (albeit for most people with a small loss in power as they sit further forward than optimal). It will descend well on steep/rough/fast. Not a big difference between this and other long/low/slack bikes, despite what Transition is claiming.

    But there's no free lunch. On flat/twisty stuff, this bike is still a LOOONG bike. It's longer than their previous models, in fact. It will require a lot of work to wrestle through corners and the front wheel is still way out in front - great for steep/fast, not great for tight and twisty.

    A lot of what they wanted to do here could have been accomplished by decreasing the reach/front center and using a longer stem. But they're apparently not brave enough to buck that industry trend, so while it's admirable that they tried to control the wheelbase a little bit - it's still a crazy long bike, just like all the other crazy long bikes that are the popular thing right now. If you like long, you'll like it. If you like quicker steering for tighter/twistier terrain, it'll be a handful.

    -Walt

  32. #32
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    Quote Originally Posted by Rumblefish2010 View Post
    So my conclusion is that it might be not possible to generalize what bike design is doing best for you. We are not similar in size, weight, skills and we have not at all the same trails.
    Of course it's not possible to generalize between different riders/preferences/terrain.

    My point was that Transition hasn't really changed things as much as they're claiming. They made the bike *longer* and *slacker* and bumped up the seat angle so it wouldn't climb horribly - this is right out of the long/slack playbook that everyone is doing right now. There's nothing wrong with it at all, if you want to feel safe/secure on steeps and you have fast/rough terrain to ride (and you don't mind sacrificing some pedaling efficiency - most people aren't as efficient sitting way forward).

    If you ride on flatter/smoother/twistier trails, all that wheelbase just hurts you.

    Basically, there's no free lunch, and there's no such thing as a bike that's optimized for everything, no matter how many fancy acronyms or short offset forks or what have you you throw on it. You have to pick what will work best for you, and if long/slack is best, that's totally cool. But it's not best for everyone, and it's not a magic free lunch.

    -Walt

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    Yes I agree. Actually if I could custom made the Sentinel, it might have been a tad less reach, and a bit higher stack. It seems I would have been between a size between the xl and large. The most demanding for me is actually dare to try different kind of frame designs. And it was a coincidence that I was desperate having no bike, that I did just try the sentinel. By the figures it should not been "my bike". Instead of choosing a bike that just should be good numbers is probably no good idea. I am not saying Transition doing any magic, but I think it is actually the combination of several design aspects together, that is the reason the bike so good. I feel The most important to me, with my size and weight, is the centered position between the wheels. It feels so natural beiing less over the rear wheel. Second it is the super progressive, and not too long rear travel. That keeps my climbing and hard descending in control. So the offset fork and slack angel is just a bonus maybe? But it feels great, not slow at all.

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    Quote Originally Posted by Walt View Post
    This is a good point. As the trail number gets higher, the ability to perceive a small change is going to drop. A track bike (~30mm trail) will ride pretty noticeably differently with a 5mm change in trail. A DH bike at 150mm trail, not so much.

    For general reference for those who are curious, here's a general trail number guide:
    -30mm or so - track bike
    -50-60mm - traditional road bike
    -65-75mm - gravel or CX bike
    -75-85mm - old school (80s, 90s) XC bike
    -85-100mm - modern XC/race bike
    -100-130mm - modern XC/trail bike
    -130mm+ - freeride/DH

    Now, you can find bikes with trail number that don't fit those categories, of course, but this encompasses 95% of what's out there.

    In general, the rougher the surface and the more you want the bike to hold a line on chunk, the higher the trail number. The smoother the surface and the less you need to worry about inconveniently placed 6" cobbles, the lower. In essence, you want the bike to do what you want it to, but not what the inconsistencies of the terrain are trying to make it do - and the trail number is how you balance out those 2 needs. High trail makes it harder for you to make the bike steer, but it also makes it better at holding a line.

    -Walt
    Cool. Thanks.

    I meant to add, when the trail number goes too far one way, the steering is "floppy" at low speed. If it goes too far the other way, it is unstable at high speed. The middle ground between floppy and skittish is comparatively wide.

    -F
    It's never easier - you just go faster.

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    Walt, just did try Sentinel with 33mm with 8degr. stem instead of original 40mm 0degr. The bike did not get better, actually it felt more unpresice and understeered? It might have put myself less over the front?
    Curious if 50mm will be better?

  36. #36
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    Quote Originally Posted by Rumblefish2010 View Post
    Walt, just did try Sentinel with 33mm with 8degr. stem instead of original 40mm 0degr. The bike did not get better, actually it felt more unpresice and understeered? It might have put myself less over the front?
    Curious if 50mm will be better?
    Only one way to find out, right?

    Most modern aggressive geometry bikes *require* the "attack" position (ie chest forward/down, elbows out, weight over front wheel) to corner decently, simply because the front wheel is so far out there. Watch a video of a pro DH rider cornering and you'll see immediately what I'm talking about.

    If your bars are too close to achieve that position easily, then it will indeed cause problems. Your stem swap has brought your weight up and back (albeit not by a ton) and that might not be what you want.

    As with any change like this, though, you need to give it a few weeks/hundreds of miles before you make up your mind - as well as swapping back occasionally to see how that feels. There's not a "right" or "wrong" position and geometry, just what works (or doesn't) for you. Part of the fun is experimenting to figure that out!

    -Walt

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    Interesting discussion. One thing I haven't seen cleared up is the difference between "quick" steering and "heavy" steering, which is an important distinction and somewhat based on rider perception and also how fast you're traveling. Also, no mention about counter-steering, which is actually how two wheelers are leaned into corners (we turn the bars left to lean the bike to the right and vice versa.)

    My motocross roots are much deeper than my MTB roots, but what I understand is that as our bikes grew more slack (HTA) they had to increase offset to make the steering more responsive at low speeds. The effect of increased offset is slightly "heavier" steering i.e. more effort at the bars when we counter steer, but when you initiate that bar movement you get more of a response.

    My estimation is that reducing offset on a modern mountain bike won't matter materially above about 5mph. Sure, the bike might steer more "lightly" i.e. less force required at the handle bars, but it will be a subtle change and won't affect performance, just the "feel" or perception of how the bike handles. Below 5mph, low gear and picking your way through a technical climb with some switchbacks is where the reduced offset will be noticed, and probably missed. The bars will move more easily, but when you turn them the bike won't actually respond as quickly to the input.

  38. #38
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    Quote Originally Posted by MikeInPA View Post
    Below 5mph, low gear and picking your way through a technical climb with some switchbacks is where the reduced offset will be noticed, and probably missed. The bars will move more easily, but when you turn them the bike won't actually respond as quickly to the input.
    I put a reduced offset fork on my new 29er just because our trails and so slow and techy. The steering is the best for these slow trails of any 29er I demo'd [all with standard 51mm offset forks] and even better than my 275er and 26er bikes.

    I think a lot of the theory and assumptions people have about fork offsets are not holding true in practice. Although to be fair it's a complicated topic confounded by numerous factors. It's also a hassle and expensive to experiment so gaining real world experience isn't easy.
    Safe riding,

    Vik
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    Quote Originally Posted by vikb View Post
    I put a reduced offset fork on my new 29er just because our trails and so slow and techy. The steering is the best for these slow trails of any 29er I demo'd [all with standard 51mm offset forks] and even better than my 275er and 26er bikes.

    I think a lot of the theory and assumptions people have about fork offsets are not holding true in practice. Although to be fair it's a complicated topic confounded by numerous factors. It's also a hassle and expensive to experiment so gaining real world experience isn't easy.
    I use the 51° off set because a lot of my trails are narrow treeline type. So the quick reactive feeling is appreciated. But I prefer less off set because of what you describe.

    Both have a trade off, at the limit of traction 51 washes and 42° trucks under the bike.

  40. #40
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    Again not back to back, but I did demo a couple similar 29ers to what I bought and the 51mm offset did not feel fast/reactive at all slow/medium trail speeds. In fact that was one of the things worrying me about pulling the trigger on a 29er because I ride tight forest trails.

    Took a chance on the lower offset and it works a treat for our trails.
    Safe riding,

    Vik
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    What MikeInPA said about riding under 5 MPH is spot on. Hard to keep it straight and steady going that slow, especially on climbs pacing off of others, with a slack HA, big wheel, low offset bike. No matter how much weight I tried to put on the front, it would just wander left or right, prompting me to stay alert in order to correct it quickly. The only real fix was to go significantly faster. I ride with slow riders, who like to go at a "gentleman's pace". One solution is to get a bike like theirs, a steep HA bike, with 51 offset, and an easy climbing gear...

    So far, I've just been sucking it up, with the meathead perspective of believing it only makes me stronger. Often I just end up walking after getting overwhelmed by the loop of over-correcting the wander, and then over-correcting my over-correction, and losing balance. Tends to happen if I get startled by someone slipping, stalling, pedal striking, or whatever. I think having room to speed up is the only way to save myself from that scenario. Locking out the fork only makes the issue worse; in fact, it only made me question what use is there for a lock out on the fork if it only makes climbing worse. For sprinting on flat ground?

    I've concluded that the low offset is more for fit and fast riders, not casual folks who just cruise around.

  42. #42
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    Quote Originally Posted by vikb View Post
    I put a reduced offset fork on my new 29er just because our trails and so slow and techy. The steering is the best for these slow trails of any 29er I demo'd [all with standard 51mm offset forks] and even better than my 275er and 26er bikes.

    I think a lot of the theory and assumptions people have about fork offsets are not holding true in practice. Although to be fair it's a complicated topic confounded by numerous factors. It's also a hassle and expensive to experiment so gaining real world experience isn't easy.
    I promise you the engineers at Trek/Specialized/Cannondale/Salsa/Ibis/etc/etc/etc are not working with "theory and assumptions." Increased offset was a direct response to fixing the low-speed ponderous handling created by slack head tube angles.

    To help understand this, exaggerate the possibilities in your mind. Imagine a massive offset of, say, 300mm. Imagine what that would do when you counter-steered. Now, imagine a negative offset of, say 25mm, with the forks behind the steering pivot. The steering would be very light, with almost no self-centering tendencies. It would also be unruly at low speeds, barely reacting to counter-steer and making balancing the bike more of a challenge. If you think this through, you'll understand the rational path the engineers followed in correcting the slack head tube angle's tendency to slow the steering down. Again, not theory and assumption....this is tried and true knowledge that has also been applied to motorcycles for many, many decades.

    All this said, you might very well like a reduced offset for your specific conditions. One man's "slow and techy" is another man's rail trail. Just know that the engineers were fixing a real problem that affects many thousands of their customers. I'm really glad they found the right compromise to give us the handling package we have on, for example, my Fuel EX8. It posses near-DH bike stability and yet climbs through rock gardens at a snail's pace....a huge performance envelope. I'm sure if it had less offset there are certain specific trails where I might find I like the handling even better, but I ride everything imaginable, and the engineers have it right....the bike is close to magic.

  43. #43
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    Quote Originally Posted by MikeInPA View Post
    I promise you the engineers at Trek/Specialized/Cannondale/Salsa/Ibis/etc/etc/etc are not working with "theory and assumptions." Increased offset was a direct response to fixing the low-speed ponderous handling created by slack head tube angles.

    To help understand this, exaggerate the possibilities in your mind. Imagine a massive offset of, say, 300mm. Imagine what that would do when you counter-steered. Now, imagine a negative offset of, say 25mm, with the forks behind the steering pivot. The steering would be very light, with almost no self-centering tendencies. It would also be unruly at low speeds, barely reacting to counter-steer and making balancing the bike more of a challenge. If you think this through, you'll understand the rational path the engineers followed in correcting the slack head tube angle's tendency to slow the steering down. Again, not theory and assumption....this is tried and true knowledge that has also been applied to motorcycles for many, many decades.

    All this said, you might very well like a reduced offset for your specific conditions. One man's "slow and techy" is another man's rail trail. Just know that the engineers were fixing a real problem that affects many thousands of their customers. I'm really glad they found the right compromise to give us the handling package we have on, for example, my Fuel EX8. It posses near-DH bike stability and yet climbs through rock gardens at a snail's pace....a huge performance envelope. I'm sure if it had less offset there are certain specific trails where I might find I like the handling even better, but I ride everything imaginable, and the engineers have it right....the bike is close to magic.
    I think it would be nice to have more options. 42 is slow at stow speeds. But I think 51 is more than needed. I'd like to find s 46 csu.

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    Quote Originally Posted by Cerberus75 View Post
    I think it would be nice to have more options. 42 is slow at stow speeds. But I think 51 is more than needed. I'd like to find s 46 csu.
    I cannot agree about what you say about fork offset at 42mm is slow at slow speed. I have had no more quicker steering bike then the Transition Sentinel, at low and high speed. Actually I am still oversteering and overshooting because of the quicker handling. So in general I mean it is wrong to say it is slower steering.

  45. #45
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    Quote Originally Posted by Rumblefish2010 View Post
    I cannot agree about what you say about fork offset at 42mm is slow at slow speed. I have had no more quicker steering bike then the Transition Sentinel, at low and high speed. Actually I am still oversteering and overshooting because of the quicker handling. So in general I mean it is wrong to say it is slower steering.
    It does depend on the bike. The longer the front center combined with a long fork will make for a quick steering bike regardless of the offset.

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    Quote Originally Posted by Cerberus75 View Post
    It does depend on the bike. The longer the front center combined with a long fork will make for a quick steering bike regardless of the offset.
    Okay, I cannot follow your logic there but I believe it is like that since that is how I feel on the Sentinel. The front center on bikes nowadays is getting longer so I believe it is more common then shorter? Fox, Rock Shocks and MRP and I believe other fork manufacturers are making or will be making 42-44mm offset forks. So we will see no missing choices for fork options in the future.....

  47. #47
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    I was curious enough to order a 44mm offset 36 for my 29/27.+ HT to replace my 34 GRIP. The bike has been amazing with 51mm, but maybe it'll corner a little more amazingly.
    Formerly Travis Bickle

    Team Robot. "modulation is code for “I suck at brake control.” Here’s a free tip: get better."

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    Quote Originally Posted by Travis Bickle View Post
    I was curious enough to order a 44mm offset 36 for my 29/27.+ HT to replace my 34 GRIP. The bike has been amazing with 51mm, but maybe it'll corner a little more amazingly.
    A great choice, just got mine dialed in. Use 5-10 less psi then recommended by Fox and use 18 click HSC from fully closed and 12 LSC from fully closed. Use as little rebound damping you can manage. It is so sweet, and you will not feel the harsh bumpy feel when riding too much air pressure, still the fork perform brilliant with small bump sensitivity and full control in the rough. It will also stay high enough in travel.

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    Well, my 44mm offset 36 and a 42mm offset Lyrik both showed up. Both are 29, the Lyrik is 140mm and I plan to use the 26 at 150mm on a FS bike that may arrive in September.

    I replaced the 150 34 with the 140mm Lyrik, and while I am still dealing in the fork it did feel more planted up front in the corners. Some has got to be a little less axle to crown, and some offset. My HT was designed for 140 and I never got around to reducing the 34. With a 30mm stem this bike doesn't feel any twitchier than any other mtb I've been on in the past 30 years. I rode a bit of tight and twisty stuff and it seems fine. I'll update after I have a decent amount of time on it.
    Formerly Travis Bickle

    Team Robot. "modulation is code for “I suck at brake control.” Here’s a free tip: get better."

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    Quote Originally Posted by StumpyandhisBike View Post
    I'm not a suspension or geometry expert but I do love to tinker and will add my experience for you to consider.

    So I was running 27+ on my Riot pretty much all the time. Only used 29's now and then. I wanted to try a different fork so sold my Pike and I bought a normal 27.5 Fox 36 160mm with 44mm offset because it had ample room for the 2.8's I was rocking. I had about 6 rides on that set up and can definitely say that the shorter offset was way better for the B+ tire. Previously, at high speeds and in flat corners I always felt like I had to muscle my turns around with the other 29 forks that I ran. Similarly, at low speeds I felt like the steering was too twitchy and couldn't get the precision I wanted. The 44mm offset fork alleviated all of that for me on the same 27.5x2.8 i30 wheels that I had always been running. Like a whole new bike. This should be no surprise as the 2.8s aren't that much taller than the rest of the 27.5 tires out there and the 44 offset is much more appropriate.

    Then for whatever reason I was missing the ability to run 29's... and as we all know once that scratch is there it has to be itched.

    So I built a new 29 wheelset and bought a set of 29 lowers for the 36 and a 150 air spring shaft and converted the fork over to a short offset 29. I only have two rides on it with 29x2.6 Rekons but I can perceive no appreciable negative to the setup. If anything I think the handling is better with the 29's than with the 27's. It's definitely better than the 51mm offset on my Pike. Its better on the climbs, I don't wander at all, more precise in the flats and tight woods, I can easily and accurately pick my lines and also is super stable on the DH's as advertised.

    It's early on though. I've only had two muddy rides on the 29's. To be fair, lots of variables changed as well. Pike was 15x100 w/51mm offset on a size small Riot frame and a noodly WTB i23 wheelset and Butcher 2.3 with control casing. New setup is a Fox 36 boost w/44mm offset on a size medium Riot with Nextie carbon i32's and Rekon 2.6 with EXO casing. The 27.5 i30 wheels, DHF 3C 2.8, and Rekon DC 2.8 rear tires, cockpit, brakes and drivetrain where all reused frame to frame.

    Regardless, this setup is working very well for me so far and I have no regrets with this setup. Again, take all that for what it is, just my initial positive experience with a reduction in offset.
    My experience exactly. People keep claiming it slows the steering...no it makes the steering more sensible.

    I live in Ok I have around 50 miles of twisty up/down Rocky woodsy trails just outside of town.
    Reducing the offset has made my bike more confident cornering and more stable at speed.

    I have a Intense Recluse with -1.5 angleset and offset bushings bike still turns on a dime.

    Imo 51mm offset is too much for 27.5/2.8.
    It makes them twitchy and the front wants to push out on flat corners.

    Anyone that wants to test what it feels like put a 27.5 tire on a 29er 51mm fork..it's not a good feeling.
    Last edited by Kevin Van Deventer; 08-01-2018 at 02:22 PM.

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    Gents, been researching for a while now and perhaps this might be the best place to get some advice. Pardon the bump of an old thread.

    I had a 2014 Stumpy (L), then 2015 Enduro (L).. Now i've decided to do a full alloy frame build of a Transition Sentinel (L). In an effort to spread out the cost a bit I decided to use the last generation Fox Factory 36 (170mm, 51mm offset). This is versus the stock 160mm travel, 44mm offset. I ride semi steep and rocky SoCal decents with mostly fire road climbs but some technical climbing about 30% of the time.

    I'm now a bit concerned of starting off with the 170mm, 51mm offset on this bike. I'm not an amazing rider but I like the descents but also not in the most amazing shape to do anything but grind up most climbs. The new geo of the Sentinel will already force me to re-learn leaning over the front bars more.

    I'm familiar with geometry changes in a car's alignment. In some ways it's a bit more complicated but i'm out of my comfort area talking about 2-wheel geo.

    Could anyone give me an idea of what to expect with the old Fox fork? Is it worth it? Will it make the handling worse? How so...? Will it destroy all the "SBG" stuff it was designed for? I was banking on the fact that my lack of relative skill might not make the higher offset and increased slack/travel from the 10mm taller fork noticeable. However, if the 160/44mm combo that comes OEM will make the bike easier, and more fun for a novice rider like myself I might just bite the bullet and buy a new fork now.

    Thanks.

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    I think the offset will be fine and especially with the extra 10mm of travel, might even make the bike a little less unruly on really slow climbs. The Sentinel is really slack at 64 degrees, so I doubt it'll end up being twitchy when things speed up. I say go for it.

  53. #53
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    Quote Originally Posted by ryu_nsx View Post
    However, if the 160/44mm combo that comes OEM will make the bike easier, and more fun for a novice rider like myself I might just bite the bullet and buy a new fork now.

    Thanks.
    If you own the 51mm offset fork already I would just use it. If you are going to buy a fork for this build get a low offset fork even if it costs a bit more The bike was designed for it and will handle best with it. That said it's not going to explode into dust at the first corner. Riders can adapt to a lot of changes and 44mm to 51mm is not the end of the world.

    https://www.pinkbike.com/news/transi...view-2017.html

    Here is what PB has to say:

    What About That Offset?

    I've been answering all sorts of questions about offset lately, many from riders who are worried about getting left behind by some sort of new “standard.” Should you rush out and buy a fork with the least amount of offset you can find? Well, no. The amount of offset does make a noticeable handling difference, but it's not as cut and dry as saying that X amount of offset is bad and Y amount of offset is good – there's more to it than that, and installing a fork with the least amount of offset possible isn't going to automatically turn your bike into a magical shred sled.

    I spent a day in the bike park switching back and forth between two Fox 36 forks, the one that came on the Sentinel, which has 44mm of offset, and one with 51mm of offset, which is what the majority of 29ers are currently spec'd with. I started off by taking three laps on the stock fork, and then made the switch to the fork with 51mm of offset. The difference is very noticeable – the increased offset felt more like what I'm used to, and the bike felt livelier, but it was also easier to oversteer and wash out the front wheel – the feeling of unlimited front wheel traction that the 44mm offset fork delivered wasn't there anymore.

    I timed all of my runs, but the numbers didn't end up indicating any statistically significant difference between the two offsets; I felt like I was able to adapt my riding style fairly quickly to both forks. After swapping back and forth between the two offsets it was clear that there are benefits to the stock, reduced offset fork on the Sentinel – namely better front wheel grip and more stability – but the bike works just fine with a 'regular' 51mm offset fork as well.
    Safe riding,

    Vik
    www.vikapproved.com

  54. #54
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    Yup, if you haven't tried the bike with 44 you won't notice. The front wheel is way out there so be careful in corners where traction is questionable. Weight the front end. I believe Vik was behind me when this lesson was reinforced for me.
    Formerly Travis Bickle

    Team Robot. "modulation is code for “I suck at brake control.” Here’s a free tip: get better."

  55. #55
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    If you already own the fork, then sure, no loss.

    If you are buying a new fork and you just don't want to spring for the cost of the newer loss offset forks, then no, I'd spend the extra cash and get the low offset fork.

    I started riding my Smash with a Lyric 160mm/51mm offset, trashed the fork on a boulder, decided to upgrade to a Lyric 160mm/42mm offset and it was a much better riding bike.

    I just built a Shred Dogg with a 36 Fit4 160mm/44mm offset.I like the Fox 36 better than the Lyric, stiffer, more supple.

    Worse case scenario, sell your fork and buy a used fork or change your CSU on your current fork ($200)

    Quote Originally Posted by ryu_nsx View Post
    Gents, been researching for a while now and perhaps this might be the best place to get some advice. Pardon the bump of an old thread.

    I had a 2014 Stumpy (L), then 2015 Enduro (L).. Now i've decided to do a full alloy frame build of a Transition Sentinel (L). In an effort to spread out the cost a bit I decided to use the last generation Fox Factory 36 (170mm, 51mm offset). This is versus the stock 160mm travel, 44mm offset. I ride semi steep and rocky SoCal decents with mostly fire road climbs but some technical climbing about 30% of the time.

    I'm now a bit concerned of starting off with the 170mm, 51mm offset on this bike. I'm not an amazing rider but I like the descents but also not in the most amazing shape to do anything but grind up most climbs. The new geo of the Sentinel will already force me to re-learn leaning over the front bars more.

    I'm familiar with geometry changes in a car's alignment. In some ways it's a bit more complicated but i'm out of my comfort area talking about 2-wheel geo.

    Could anyone give me an idea of what to expect with the old Fox fork? Is it worth it? Will it make the handling worse? How so...? Will it destroy all the "SBG" stuff it was designed for? I was banking on the fact that my lack of relative skill might not make the higher offset and increased slack/travel from the 10mm taller fork noticeable. However, if the 160/44mm combo that comes OEM will make the bike easier, and more fun for a novice rider like myself I might just bite the bullet and buy a new fork now.

    Thanks.
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  56. #56
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    Going from a 51 to a 44 offset is a change of 7mm, which is a ~0.6% decrease in wheelbase. This is essentially inconsequential, IMO. It is also a 7mm increase in trail, which is roughly a 7% change. This is a 10x larger relative change, but still has pretty small effect, as pointed out in the comparisons already mentioned.

    I'll point out that the 51mm offset arose as a means to partially counter the increase in trail caused by going to 29r wheels, which slowed steering and handling, which is bad for climbing and tight slow maneuvering but can be beneficial for fast descending.
    Do the math.

  57. #57
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    The change in wheelbase is not that significant.

    The change in trail is significant: 17%

    So yes, it will make the bike ride differently.

    Shortening trail generally works best on slacker HTA, <66 deg

    Quote Originally Posted by Lone Rager View Post
    Going from a 51 to a 44 offset is a change of 7mm, which is a ~0.6% decrease in wheelbase. This is essentially inconsequential, IMO. It is also a 7mm increase in trail, which is roughly a 7% change. This is a 10x larger relative change, but still has pretty small effect, as pointed out in the comparisons already mentioned.

    I'll point out that the 51mm offset arose as a means to partially counter the increase in trail caused by going to 29r wheels, which slowed steering and handling, which is bad for climbing and tight slow maneuvering but can be beneficial for fast descending.
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  58. #58
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    Quote Originally Posted by Nurse Ben View Post
    ...The change in trail is significant: 17%...
    It depends on the HT angle, etc, but typical trail is ~100mm so 7mm is around 7% by my calculations.
    Do the math.

  59. #59
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    One negative for me in reducing offset is it raises the front of the bike. So if you're running your bars slammed already as I am it may bother you.

  60. #60
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    Quote Originally Posted by Kevin Van Deventer View Post
    One negative for me in reducing offset is it raises the front of the bike. So if you're running your bars slammed already as I am it may bother you.
    Correct me if I'm doing bad geometry, but I think a shorter offset would actually drop the front end or maybe it makes no difference...

    Either way, that's a pretty small increase, a mm or so, man you are sensitive
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  61. #61
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    Quote Originally Posted by Nurse Ben View Post
    Umm, ya think?

    That's a pretty small increase, a mm or so, man you are sensitive
    I'm also running an angleset so the front of my bike is as high as I would like it to go for my riding style.

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