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Cassette worn causing slipping?

I broke my bike!

Well maybe not...I've been getting a slipping as if its going over the cogs on the lower gears on the rear. This is worse under load, like just setting off from a junction where you don't want to suddenly lose power (not that i have much).

It went to the lbs today and they serviced it, but its still happening. Does the cassette look worn? I feel like they would have mentioned this, they're quite reputable, but wanted to see what you all thought since all the tweaking didn't do the job. Shifting is fine, omits going through the gears pretty smoothly.


  • MattFalleMattFalle Posts: 11,644
    can you put your chain on the big ring and pull it forward so we can see how stretched it is please thank you
    The camera down the willy isn't anything like as bad as it sounds.
  • trigger13trigger13 Posts: 11
    I'll have a play tomorrow Matt thanks for getting back to me.

    I forgot to say, this is after a new chain. Links are the same i am 98% sure. But ill do this anyway if it'll help! :)
  • veronese68veronese68 Posts: 26,939 Lives Here
    Slipping after fitting a new chain is usually caused by the cassette being worn, hard to be certain looking at it but almost certainly the case. Does it slip in all gears on the cassette or only the ones you used the most?
    Sometimes you can replace the chain and get away with it, depends how worn the chain was. If you call the bike shop and tell them what's happening they'll tell you the cassette probably needs replacing.
  • bobmcstuffbobmcstuff Posts: 11,178
    Also take a look at your chainset... there's only 2 of those so they take a lot of use... mine got really rounded and slipped under power every time I went uphill...
  • paulwoodpaulwood Posts: 231
    Almost certainly a worn cassette if you have changed the chain. Do that first and then consider the chainrings if it still happened.
  • trigger13trigger13 Posts: 11
    Thanks for all the advice! I went for a quick ride and its definitely just the lower gears its happening so ill go with cassette and see what happens. I also made the rookie mistake of going out without a out puncture plan for the first time in ages...and had my first puncture in years....just thought I'd give you all a chance to tut and laugh at me :D
  • kangarougekangarouge Posts: 210
    I had the very same thing recently and was just about to order a new cassette but thought I will just check it over again before I do. It turned out to be the rear mech. not returning in low gears to take up the slack in the chain. Hence, the chain then slipped when it was placed under load.
    I loosened the appropriate Allen bolt, cleaned it as best I could and applied some oil. Problem solved. Though I do agree, it could be the cassette.
  • WheelspinnerWheelspinner Posts: 6,464
    Had an old 8 speed cassette that was doing this, especially on the smaller cogs under load only. In the workstand it shifted perfectly but riding it would jump a lit.

    Turned out the cassette spline was worn enough it was not locking on the freehub sufficiently and rotated under load.

    New cassette, problem fixed.
    Open One+ BMC TE29 Seven 622SL On One Scandal Cervelo RS
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