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  1. #1
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    42mm offset 29er forks

    anyone else out there interested in the 'new' fork offset geometry thats being touted? if available aftermarket i'd like to go from my 51 to a 42mm offset on my Smuggler and see if it provides the handling benefits discussed by Whyte bicycles and Transition. i've gone from 130 stock to 140 and trail would increase further with a 42 offset. could also be all bollocks and a waste of money, so it's unlikely i would pull that trigger if i'm to be honest with myself!

  2. #2
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    I am. Problem is I'm having a heck of a time locating a 160mm 29er fork with reduced offset. I'm currently limited to the MRP Ribbon and FOX 36 160mm 29er with 275 CSU installed.

  3. #3
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    i imagine they will become available to the public at some point but for the near future, a custom thing for a few manufacturers me thinks....

  4. #4
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    Won't make the difference you think til damn near stall speed. Tried 46 and 51 pike on my ROS, preferred 51. But at speed meh, YMMV. Don't blame the equipment.
    ROS9+ SS
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  5. #5
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    What is this 2003? What are the "benefits" they are claiming?

  6. #6
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    Because the head angles get very slack nowadays, the trail increases to a level which seems to make steering awkward. So they go back to less offset.
    Just after we had increased the offset because after introducing bigger wheels we found out they handled awkward.
    Probably, if you would compare the trail of 2010s best 26" with the trail of 2015s best 29" it matches up with the trail of 2018s reduced offset bikes
    there probably are "golden numbers" somewhere, we just ignore them when we change some parts.

  7. #7
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    But that's not how it works. A larger wheel INCREASES trail. A slacker head angle INCREASES trail. A shorter fork offset also INCREASES trail.

    So as wheels got bigger and head angles got more slack, fork offsets got LONGER to battle the slow steering and handling that everyone complained about.

    This is going backwards, right to when everyone hated 29ers.

    Quote Originally Posted by Lochnes View Post
    Because the head angles get very slack nowadays, the trail increases to a level which seems to make steering awkward. So they go back to less offset.
    Just after we had increased the offset because after introducing bigger wheels we found out they handled awkward.
    Probably, if you would compare the trail of 2010s best 26" with the trail of 2015s best 29" it matches up with the trail of 2018s reduced offset bikes
    there probably are "golden numbers" somewhere, we just ignore them when we change some parts.

  8. #8
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    [QUOTE=Black Squirrel;13258724]But that's not how it works. A larger wheel INCREASES trail. A slacker head angle INCREASES trail. A shorter fork offset also INCREASES trail.

    bullocks, I managed to fumble it upside down again; you are right.

    which leaves me even more wondering "why?". had both a bigger and shorter offset fork on my bike and really liked the bigger offset better

  9. #9
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    Do the math.

  10. #10
    wanna ride bikes?
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    Quote Originally Posted by Lochnes View Post
    bullocks, I managed to fumble it upside down again; you are right.

    which leaves me even more wondering "why?". had both a bigger and shorter offset fork on my bike and really liked the bigger offset better
    What do you consider as "better" handling? do you want a more nimble bike for tight and twisty trails or a more stable bike at higher speeds? Sounds like you prefer a quick steering bike, which would mean you want a higher offset fork. Example: Slack HTA's slow the steering down, using a fork with 51mm of offset will speed it back up a bit. Though it depends on what your after and what/where/how you ride, you may prefer less offset and more stable handling characteristics.

    I linked some good articles when I asked this question a while back. You can ignore the details about it being a rigid fork and what it's suspension corrected for and just stick to the info about offset, the same

    Rigid fork offset
    Rigid SS 29er
    Fat Lefty
    SS MonsterCross
    SS cyclocross
    all steel

    Stop asking how much it weighs and just go ride it.

  11. #11
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    I've had two bikes that I was able to swap fork offset on back to back to see the difference. I preferred the larger offset on both for high speed and making my way quickly through tight trees. I the differences between the handling of varying offsets did not seem to align with the theoretical effect discussed. To me, both bikes seemed more predicable and more playful with the larger offsets, with fewer corrections required mid turn. The difference was more distinct on the rigid bike, but it also had a larger difference between the offsets trialed.

    Bike 1:

    Scott Genius 29, 140mm Pikes tried. 46mm & 51mm offsets.

    Bike 2:

    Scott Scale 29, ENVE Rigid fork (flip chip for changing offset, this is a great fork for experimenting with the affect of changing offset). 44mm & 52mm offsets.

  12. #12
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    Quote Originally Posted by *OneSpeed* View Post
    What do you consider as "better" handling? do you want a more nimble bike for tight and twisty trails or a more stable bike at higher speeds?
    Yeah, my greatest challenge is not hitting the trees, so like faster steering. More offset really did mean hitting less trees.
    Not that meany high speed downhill sections here, and on those ones we do have i"m already pretty fast

  13. #13
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    Quote Originally Posted by Lochnes View Post
    which leaves me even more wondering "why?".
    Some brands are looking for even more straight-line stability in their bikes. Certain bikes on the right terrain might benefit from that, like an all-out plow enduro race bike meant for relatively fast courses.

    Lengthening the reach is one option, and bikes have gotten a lot longer, but we're probably at the limits of what can be done there, within the constraints of sizing. Long reach has also allowed stems to get shorter, but you can't really make a stem shorter than 35mm (Pacenti P-Dent notwithstanding).

    You can slacken the headtube angle, which increases trail, but there's a limit there. AM/enduro bikes are settling around 65deg, as going slacker has other negative handling issues - keeping the front weighted, wheel flop, potentially reduced fork sensitivity, etc.

    You can lengthen the chainstay, but that affects cornering. It's hard to carve with a long rear end, as the first wave of 29ers demonstrated.

    And all three of those increase wheelbase, so the bike becomes harder to maneuver in general. Since we're over 1200mm in many bikes in the category, we might be the limit of what makes sense there.

    So, a few manufacturers are experimenting with fork offset to add more stability without the negative effects of the other options - it even slightly reduces wheelbase The steering input will feel slower, but that can be partially compensated with an even shorter stem. And for the speeds intended, you aren't exactly making super large movements of the bars anyway.

    For a more general-purpose trail bike, where you actually do care about low speed maneuverability, it probably doesn't make as much sense. But maybe we'll see a more modest change as a way to get more downhill capability in shorter-travel bikes too.

  14. #14
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    lazarus, that is definitely a good answer to the question "why".

    so, to get out of a corner of the "design box" which was starting to show deminishing results such as reduced fork sensitivity, this is a new direction. I can follow that.

    but, then comes the next question:
    <philosophicall alert>why do we all seem to want super downhill sleds? yes it is great fun but i think most distance is made outside the bike park. is it human behavior that we all seem to want big 4 x 4 "s to go to the mall and enduro downill sleds to do our local round?</philosophicall alert>

    lets get back to the technicall aspects.

  15. #15
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    Quote Originally Posted by brentos View Post
    I've had two bikes that I was able to swap fork offset on back to back to see the difference. I preferred the larger offset on both for high speed and making my way quickly through tight trees. I the differences between the handling of varying offsets did not seem to align with the theoretical effect discussed. To me, both bikes seemed more predicable and more playful with the larger offsets, with fewer corrections required mid turn. The difference was more distinct on the rigid bike, but it also had a larger difference between the offsets trialed.

    Bike 1:

    Scott Genius 29, 140mm Pikes tried. 46mm & 51mm offsets.

    Bike 2:

    Scott Scale 29, ENVE Rigid fork (flip chip for changing offset, this is a great fork for experimenting with the affect of changing offset). 44mm & 52mm offsets.
    This^^^ My LBS mistakenly ordered a 46mm offset SID for my new Scale build, was supposed to be a 51mm.
    They told me to ride it as is and that rockshox was sending them a new 51mm crown assembly.
    I rode my new Scale and was underwhelmed with the way my new Scale handled with the 46mm offset, to the point where I was questioning my bike choice.
    Long story short, the fork was changed to a 51mm offset and it completely transformed the way the bike handles, rather than thinking and muscling the bike thru turns it now became automatic, as it should be.
    I have noticed no loss of straight line stability, as it has been mentioned the front wheel should get knocked off line more easily with a larger offset.
    Count me in as a fan of the larger offset #'s

  16. #16
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    Quote Originally Posted by Lochnes View Post
    <philosophicall alert>why do we all seem to want super downhill sleds? yes it is great fun but i think most distance is made outside the bike park. is it human behavior that we all seem to want big 4 x 4 "s to go to the mall and enduro downill sleds to do our local round?</philosophicall alert>
    Well, it depends on terrain, intended use, etc.

    I'll be the first to admit that my 165mm super-enduro-AM-whatever leaves me overbiked for my local trails, and that I need to drive at least two hours to really stretch its legs. I'd certainly be faster and maybe have more fun on the weeknights with a little 110mm whip, but the super downhill sled bike is what I really do want on the weekends, when I can get to real mountains, bike parks, trails with features, etc.

    For a case like Anthem1's Scale, with more traditional XC geometry, probably doing more traditional XC riding, likely with lower peak speeds and for shorter durations, likely over less demanding terrain (sorry if I'm assuming too much about your riding, just generalizing), you'd naturally expect a different compromise to make sense.

    What I think's really interesting is what's happening in the 120mm-140mm trail bike category, where we're seeing bikes that are so much more capable than a few years ago due to improvements in geometry and suspension design, but still manage to stay light and playful. Maybe a shorter offset has some application there.

  17. #17
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    My other bike is a Pivot Switchblade with the Fox 36 also at 51mm offset, IMO 29ers with slacker HTA's is where more offset really shines.

  18. #18
    Ride Fast Take Chances :)
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    I just ordered a Fox 34 CSU in 44mm offset for my tallboy 3 29er.
    I want more trail for stability, but the main reason it that the front is too long. I ride an XXL and the front to rear weight balance is shifted to far rearward. I need the decreased offset to help weight the front as I can't stretch the back out. I will report back in a month when I get the new CSU.

  19. #19
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    Quote Originally Posted by alexbn921 View Post
    I just ordered a Fox 34 CSU in 44mm offset for my tallboy 3 29er.
    I want more trail for stability, but the main reason it that the front is too long. I ride an XXL and the front to rear weight balance is shifted to far rearward. I need the decreased offset to help weight the front as I can't stretch the back out. I will report back in a month when I get the new CSU.
    Interesting, I too have an XXL bike (23" Fuel EX).
    I ride it as a plus bike most of the time, which makes the bottom bracket rather low. Running it in the high setting solves this but makes the trail fairly short. A taller fork could help, but the wheelbase is already quite long.
    The current trend is for longer bikes for stability, but that's because reviewers and engineers are talking about M and L size frames. XXL's are already quite long.

    Since most brands keep the chainstays the same length, the weight distribution is more rearward on a larger bike, so I think this idea makes a lot of sense.

  20. #20
    Ride Fast Take Chances :)
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    Just got my new 44mm CSU installed today. Parking lot test: the bike feels shorter, but the steering feel very similar.

  21. #21
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    Quote Originally Posted by alexbn921 View Post
    Just got my new 44mm CSU installed today. Parking lot test: the bike feels shorter, but the steering feel very similar.
    Cool, let us know how it is on the trails!

  22. #22
    Ride Fast Take Chances :)
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    2 rides on the bike. Set 2 PR's on steep DH sections. Can feel the extra feedback when leaned over at the limit. Still trying to find the balance and dial in the speed of the steering. So far I like it. No low speed side effects so far.

  23. #23
    SyT
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    I went to 42mm on my ht 29er and like it better overall ( after playing w 46 & 51) but will say that the higher offsets work better ( for me) on our tightest, slowest tech trails here in Indiana. I won't be going back and in fact am in process of shopping for angle set in pursuit of a few more mm of trail.

  24. #24
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    Few more fork options:

    Use a new Rockshox 27.5 fork. Officially ok for 27.5x2.8, so smaller 29er tires should fit to. Note lower AC height, so might want to get longer travel.

    XFusion Mc Queen fork: 46mm offset and clearance for 29x2.6 officially, more in practice.
    Note very tall AC, so might want to adjust to lower travel.

    XFusion Revel upside down fork: "27.5" version has 46mm offset, then limit travel top keep tire from hitting crown/frame on full compression.

  25. #25
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    Reducing fork offset for taller riders

    moved to tall rider forums:

    here
    Last edited by Tjaard; 10-13-2017 at 08:58 AM. Reason: moved post

  26. #26
    SyT
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    Quote Originally Posted by Tjaard View Post
    Few more fork options:

    Use a new Rockshox 27.5 fork. Officially ok for 27.5x2.8, so smaller 29er tires should fit to. Note lower AC height, so might want to get longer travel.

    XFusion Mc Queen fork: 46mm offset and clearance for 29x2.6 officially, more in practice.
    Note very tall AC, so might want to adjust to lower travel.

    XFusion Revel upside down fork: "27.5" version has 46mm offset, then limit travel top keep tire from hitting crown/frame on full compression.
    The 27.5 csu mates to the 29 lower for Rockshox, which is the route I chose. No additional clearance issues with that set-up.

  27. #27
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    Quote Originally Posted by SyT View Post
    The 27.5 csu mates to the 29 lower for Rockshox, which is the route I chose. No additional clearance issues with that set-up.
    that sounds nice, does this work? i have a 29er Pike from 2013 with the 46 offset and a good offer for a 27.5 csu (11.4018.008.419). I've ordered a carbon Smuggler frame an want to test the lower offset.

  28. #28
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    29er's have gotten more capable via better geo etc.

    So, naturally if people are riding them on steeper, faster, gnarlier terrain - they'll want it to be calmer when going mach chicken via reducing the offset.

    Totally logical Captain.

    'We'll all make it to the top... Some of us, might not make it to the bottom'
    "Mountain biking: the under-rated and drug-free antidepressant"

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