chain jumping around on middle 3 sprockets…….help

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  • chain jumping around on middle 3 sprockets…….help
  • Premier Icon njee20
    Subscriber

    Something’s worn.

    Premier Icon scotroutes
    Subscriber

    Is this the new bike Ton? What shifter/mech/cassette are you using?

    new chain on worn cassette?
    chain & cassette worn out completely
    rear mech or bent
    just guesses, very difficult to diagnose without seeing it.

    How old is the drivetrain?

    Premier Icon ton
    Subscriber

    new bike. using road version of flat bar shifters.
    but it was doing it with the drop bar sti units too.

    Trimix
    Member

    Most likely cause is a slighty out of line mech. It only needs to be out a tiny bit. Even a new hanger can need a tweak to get it right, also check you tightened it to the frame properly, mine came ever so slightly loose which caused a similar thing. Check that first, then chech the other things metioned.

    bikebouy
    Member

    +1 for another “mech out of line” answer.

    Or try the cables, they may be dry in the outers and a good lube my just release that teeny bit of snag that could be making the inner “stick”.. Worth a go IMO.

    Another, check the cable routage, have you a cable carrier thingy under the BB? Lube that too..

    Mark N
    Member

    Given that it seems to happen when riding it therefore when chain has load applied I would strongly suspect the chain/cassette. You say new bike. Is this new out of the box never been used or newish, ridden and been okay for a while but now has the issue.

    Premier Icon ton
    Subscriber

    ok for first 2 rides then started.

    Cassette locking tight?

    Premier Icon ton
    Subscriber

    my chain is jumping around on the middle 3 cogs of a 9spd set up.
    no amount of tuning will stop it.
    when the chain is in each of the 9 cogs whilst on the workstand it works fine and dandy.

    any ideas?

    chives
    Member

    Shimano chain? I had a joining pin that had sheared leaving a protruding bit which rode up on the next biggest sprocket (like a phantom shift). That was ten speed though. Or have you had a stone strike on the chain, opening a link slightly? Seems odd it’s in the middle of the block though (straightest chainline) my troubles’ always shown up on the smallest sprocket.

    djc1245
    Member

    I had similar a few weeks ago(bottom 3 cogs). Changed to a new cassette and it was fine after that

    Premier Icon igm
    Subscriber

    Ok in workstand, but not under load.

    Does it matter which chainring you’re in? Is the chainline right?

    You’re an old soldier so I assume you’ve tried pulling the chain backwards off the offending sprockets to check for wear. Pull it forward off the chainring too and it helps indicate whether it is the chain or sprocket at fault.

    Had something similar once when I put the cable through the clamp on the mech slightly out of alignment (effectively got slightly wrong pull ratio) but I’d expect that to influence top or bottom sprockets not middle – and if you’ve changed shifters then you’d have had to have done it twice.

    Premier Icon ton
    Subscriber

    did a bit of tweaking earlier, nipped the lockring up, checked the dropout, adjusted the cables and checked for snagging. all good.
    just been for a bit of a spin, and it seems fine…..we will see.

    cheers all.

    Mark N
    Member

    Glad you seemed to have got it sorted.

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