Join Date: Sep 2005
Location: Essex, MD
Bikes: Ridley X-Fire (carbon, white)
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Originally Posted by legstwelve
so how do i fix it? It's a CAAD5 frame so its pretty stiff.
If the frame is flexing enough to cause an "autoshift", then you may have the right barrel adjuster a little too tight. Give it a little turn in the direction that effectively shortens the inner wire's length. This will cause the inner wire to be less tense. Keep track of how many quarter-turn adjustments you made.
Initially, you could test the adjustment while the bike is mounted on a cycle trainer with the roller locked out or on a mechanic's stand. If it shifts well through the entire cog (i.e., the rear cassette's gears) range, then test it on the road.
If this is not the problem, then the inner wire may be getting hung up somewhere. Look for broken strands within the working range of the exposed inner wire, especially under the bottom bracket or just after or before where the inner wire is protected by cable sleeving. Don't forget to give the wire in the shifter a look as well. If you don't see anything then it may be something hidden by the cable sleeving. Either way, if the wire is fraying, best to get it replaced.
You may be able to see more of the wire if you shift to the highest gear on the cassette, then use your hand to pull the wire where it's exposed anywhere before the bottom bracket.
Make sure that if you only intend to replace the inner wire (you usually do not have to replace the entire cable set) that the cable sleeving is given a good douching with teflon spray lube before you run the inner wire.
If no fraying is evident, then try some teflon spray at the bottom bracket guides and just before the inner wire runs into cable sleeving.
If none of this works, then perhaps it may be a worn drivetrain. I'd start by replacing the cassette and chain at the same time. Lastly, you could replace the chain ring.
Hope this gives you an idea of what to look at.