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  1. #1
    Senior Member Raging_Bulls's Avatar
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    Reducing Reba travel beyond claimed specifications? (aiming for 50mm travel)

    I'm rebuilding one of my bikes, which is equipped with a 2011 Reba RL set at 100mm length.
    Seeing as the bike will only be used on the road and I actually prefer oldschool looks and geometry, I want to drastically lower the front end.
    No worries, I've done all my calculations regarding headtube angle, rake, BB height, etc, and it all works out. I also tested the bike with an old 55mm fork and that worked fine (apart from having bouncy elastomers and no front brake). In fact it was still more slack than the bikes of the early '90s.
    So basically that's the plan. I want to lower the Reba to somewhere in the 50-60mm region.

    The specs say that the Reba can be adjusted from 120mm to 80mm by adding spacers on the main shaft in the left leg.
    According to the pics I see in the manuals online (see the pic of step 8 in this one for example), it's a plain straight axle of constant diameter.
    I see no reason why it wouldn't be possible to add more spacers, but nobody on the internet seems to talk about shortening (makes sense, everyone wants 200+mm nowadays) and when you mail SRAM to ask about the possibility, their reply is a default mail with the known specs.

    Can it be done? Has anyone here done this already or knows the inside of the Reba good enough to tell if it's plausible? I wouldn't want to put it all back together and then have the whole thing blow up on the first stroke.
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  2. #2
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    Will reducing the travel actually lower the front end or just make it bottom out sooner? Its hard to tell from the shock internals.... What you really want to do is set a really low pre-load so that the shock is naturally compressed a lot by default.

  3. #3
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    Quote Originally Posted by gsa103 View Post
    Will reducing the travel actually lower the front end or just make it bottom out sooner?
    Pardon my ignorance here, but I had the same question. It would seem to me that the amount of travel a fork wants is a function of the G-force it's expected to absorb and it's stiffness.

    I'd expect that if you simply shortened the travel without making the springs stiffer you'd bottom out more often. OTOH if you stiffen the fork, you don't need to limit the travel, since the stiffness alone would do the same thing.

    Again, I'm not familiar with this fork (or any other suspension fork either).
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  4. #4
    biked well well biked's Avatar
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    Adding more than the recommended amount of fork oil should reduce the travel, not sure at what point that might be damaging or how much you could reduce the travel by doing it. I have rebuilt Reba's before and have found that if you put even a very small amount more fork oil than the recommended spec, the travel is reduced. I've seen as much as 10-15mm reduction in travel on a Reba set up for 100mm with slightly too much oil, although it wasn't my original intention for that to happen. Of course, that was fairly easily corrected. YMMV.

    To give you my honest opinion, the idea of drastically reducing the travel beyond spec on a pretty nice, modern suspension fork seems kind of silly to me, and I think that even if you're able to do it, to do it as much as you want is likely going to make the fork act more like dead weight than a suspension fork. But please just take that for what it is, an opinion. I've never done what you're trying to do exactly, so for all I know you can make it work exactly as you like.

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    biked well well biked's Avatar
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    Quote Originally Posted by gsa103 View Post
    Will reducing the travel actually lower the front end or just make it bottom out sooner?
    On a Reba, reducing the travel should make the fork shorter (therefore lowering the front of the bike) and make it bottom out sooner, assuming you use the same amount of air pressure as before.

    As an aside, the OP's 2011 Reba uses Dual Air I believe, with separate positive and negative air, while more recent 2013 and 2014 Reba's use Solo Air which allow the user to fill from one valve and keeps the positive and negative air pressure equal.

  6. #6
    Senior Member Raging_Bulls's Avatar
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    Indeed, mine is a dual air. I was running it on 110psi in both chambers and the Reba is rated to 200psi max, so firming it up shouldn't be much of a problem.
    No idea how the required amount of pressure scales as you shorten the fork, but I doubt it's linear. Maybe I should start with 60mm, spend a week playing with pressures and rebound until I get it to how I like, then see if there's room for more.

    My intent is to get the lowering purely by adding spacers inside the upper left leg, as per the manual I listed in my OP. The long shaft that starts in the upper leg and bolts to the bottom of the lower leg would then extend less from the upper leg, basically keeping the fork short.
    Seeing as the damper unit is in the drive-side leg, that wouldn't require any fettling. Interesting comment regarding the damper oil though. I'll keep that in mind in case 80mm really is as far as it'll go by normal means.

    As for your honest opinion, it's noted. However I do have my reasons to go for this approach.

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    I've seen a Rockshox lowered to abt 60 mm travel that way. Someone wanted to run 26" wheels in a 29" fork.

  8. #8
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    Quote Originally Posted by gsa103 View Post
    Will reducing the travel actually lower the front end or just make it bottom out sooner? Its hard to tell from the shock internals.... What you really want to do is set a really low pre-load so that the shock is naturally compressed a lot by default.
    Reducing travel does lower the front end, and for the same amount of pressure make it bottom out faster. But simpy running a fork with a lot of sag isn't the same. you'll get a lot of mushy travel before the fork starts working as intended.

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