Gears chatter but only on smaller sprockets: why?

fearby
fearby Posts: 245
edited February 2008 in Workshop
Using Campag Chorus rear mech and a new (ish) chain. Tightened rear mech cable and was all working fine until a week or two ago after a Winter's steady use. Is it my brake/gear shifters needing adjustment? Don't think it is the indexing of the mech because the three largest sprockets don't cause any problems.

Hmmmmmm :?

Comments

  • Phil Russell
    Phil Russell Posts: 1,736
    Step 1: check that the chain is not a bit stiff in places. This could cause it to not want to go around smaller cogs as easily and so chatter.
    Give it a clean and relube.
    Check that the rear mech can move freely across the cassette. a bit of stiffness due to winter crud can cause the chatter.
    If this fails .. we look elsewhere.
    Cheers, Phil
  • scherrit
    scherrit Posts: 360
    Sticky cable not letting the shifter come back smartly when the return spring in the shifter is in a range of less springyness (smaller cogs)?? Cable could be sticky on the under BB point, or in the section of housing to the shifter mech? bent hanger? as above, sticky shifter pivots? Plenty to try!
    Good luck,
    S.
    If you're as fat as me, all bikes are bendy.
  • jonba
    jonba Posts: 15
    Check that the teeth aren't worn. If you've replaced the chain and not the casette then wear will mean things don't quite mesh properly. Small cogs will wear faster than the big ones so might explain why only the small ones give you a problem.

    Also check the limit screws on the mech. Not likely but possible a problem there.
  • Steve I
    Steve I Posts: 428
    Have you knocked the rear mech in some way? This can bend the hanger slightly and affect the indexing.
  • fearby
    fearby Posts: 245
    I have had a closer look. The cable may not be seated as it should and the lock ring on the cassette was loose. Will be back if things aren't fixed. :?
  • fearby
    fearby Posts: 245
    I think it was the lockring - wasn't expecting it to have loosened. All going fine now. :oops:
  • robbarker
    robbarker Posts: 1,367
    Chattering? You haven't bought female sprockets have you?

    <runs away and hides>
  • redvee
    redvee Posts: 11,922
    The wrong lockring on Shimano cassettes can produce chatter. Usually caused by using a 12t lockring on an 11t sprocket.
    I've added a signature to prove it is still possible.
  • alfablue
    alfablue Posts: 8,497
    My lockring has come loose a couple of times despite very firm tightening (and it is the correct one), so I put some threadlock (one that is fairly easy to undo) on it last time, the problem seems to be resolved now.

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