Rear derailleur and slipping gears

andy81
andy81 Posts: 118
edited January 2014 in Workshop
I had a crash a little while back which resulted in the rear derailleur being bent into the spokes. I took the bike in for repair at my local shop, and whilst they replaced the mech hanger, they managed to 'rescue' the derailleur. I've only used the bike a couple of times on the turbo since, but have found that often when I shift into higher gears (big ring, smaller sprockets), as soon as I put real force through the pedals, it shifts another 2-3 gears down the sprocket.

Could this be the derailleur needing replacement, as based on the workload the chain has had I don't think it's a worn chain (also this problem didn't happen pre-crash). Any thoughts welcome.

Andy

Comments

  • arlowood
    arlowood Posts: 2,561
    Sounds like insufficient cable tension which is allowing the derailleur "parallelogram" to pull the chain into the higher gears when under load.

    Firstly just try turning the barrel adjuster anticlockwise by 1 turn and check if this improves things. If not try another turn and so on.
  • desweller
    desweller Posts: 5,175
    Check that the derailleur hanger screws are tight and that the b-screw is sitting on the hanger correctly. The derailleur shouldn't 'know' what force you're putting on the chain as it's on the untensioned side. So something is moving around when you load the frame up.

    Some photos might be helpful.
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    On Strava.{/url}
  • andy81
    andy81 Posts: 118
    Thanks, I'll try both of the above. Sounds like the more likely explanation is that there's a setup issue rather than a dodgy derailleur, which is good to hear!
  • keef66
    keef66 Posts: 13,123
    You sure the wheel isn't moving in the dropouts?

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