• 10-28-2012
    James8101
    Troubleshooting rear derailleur
    After riding on a rocky section of trail, my chain seems to skip about on the cassette. This doesn't happen all the time, or on pavement...basically during a race, I'll hear and feel the chain shift about on the cassette once or twice an hour.

    I've been told this is normal--is this the case?

    It's a 4 year old XT deraileur, new jockey wheels, new XT cassette, chain and cable. I've setup the shifting and had it checked by my LBS, and the hanger looks ok--not obviously bent, and doesn't look any different to my spare one. Could the chain be too long? I've set it up as per Zinn's book, and one shop already thought it was too short...



    Thanks!
  • 10-28-2012
    Kristatos
    Sounds like you've checked off most of the boxes already.

    Since your derailleur is 4 yrs old it's not the shadow-plus type which prevents some amount of chain slap. That could be a possible upgrade. It basically would put additional tension on the chain over those rocky sections, making it less likely that the chain would jump around.

    You could also check any suspension pivots, removable derailleur hangers and other rear end bolts to snug everything up, just in case.
  • 10-29-2012
    thomllama
    Quote:

    Originally Posted by James8101 View Post
    After riding on a rocky section of trail, my chain seems to skip about on the cassette. This doesn't happen all the time, or on pavement...basically during a race, I'll hear and feel the chain shift about on the cassette once or twice an hour.

    I've been told this is normal--is this the case?

    It's a 4 year old XT deraileur, new jockey wheels, new XT cassette, chain and cable. I've setup the shifting and had it checked by my LBS, and the hanger looks ok--not obviously bent, and doesn't look any different to my spare one. Could the chain be too long? I've set it up as per Zinn's book, and one shop already thought it was too short...
    Thanks!

    bent hanger is not something you can eyeball.. you'll never even see an out of alignment hanger... get the tool and check it.
    check "b" screw adjustment
    Do the Big-Big check of chain length.. but I doubt it's that if it's doing it thru the whole range of the cassette..

    Old front rings? I changed everything recently and the front rings were causing a wicked jump/skip feel.. thought it was miss shifting at first...
  • 10-29-2012
    cautery
    My bet would be a combination of things all getting together...

    1) Worn chain rings - typically, if you replace a cassette for worn cogs or to upgrade it, but it has some mile son it, the chain rings likely have wear quite different from a new cassette causing some problems... ALSO, the chain... ypically, I try to replace cassette, rings, and chain at the same time to make sure they all wear at the same rate.
    2) Improperly set B-screw (possibly set to compensate for a weakened derailleur return spring.
    3) slightly out of spec hanger...

    I had the same problem once, and in my case it was a bad hanger that was almost indistinguishable from a new one by eye...