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Bottom bracket, crank problem

kirksterkirkster Posts: 8
edited January 2010 in Workshop
I was stationary on an hill today and as you do, to get moving it takes a lot of torque and initial power to get going. What happened is that the bottom bracket slipped about 90 and the cranks just slipped and as such I lost power and nearly fell. Didn't do it again though.

Any ideas what to check here or what the matter might be? Not too sure what to tighten or look at. Its Campag Veloce 2005, and I must say i have not had any maintenance on the cranks/bottom bracket for ages. getting back into biking after baby enforced lay off for three years....

Thanks guys,



  • Smokin JoeSmokin Joe Posts: 2,706
    A bottom bracket can't do that, and even if it did you would not lose any drive because your chainring is still turning with the cranks.

    From your description I would suspect your tyre just spun.
  • Mike67Mike67 Posts: 585
    Could be that your chain slipped off/around the teeth on your cassette or chainring when you put the power down.

    Do they look worn at all?
    Mike B

    Cannondale CAAD9
    Kinesis Pro 5 cross bike
    Lots of bits
  • LimburgerLimburger Posts: 346
    Chain jumping or the freehub on its way out.

    Freehub on my commuter just bit the dust, when it started to go I though it was the chain jumping but it got progressively worse until pedaling results in no forward motion.
    God made the Earth. The Dutch made The Netherlands

    FCN 11/12 - Ocasional beardy
  • PokerfacePokerface Posts: 7,960
    Yup - sounds like a worn out chain, chainrings or cassette.

    Have had the same thing happen to me in the past and the teeth on my chainring were worn out - chain would slip under pressure.
  • Thanks for the replies guys. Some food for thought there.

    Chainrings and chain look OK - I'll get it looked at. Could be that the wheel slipped.

    Is the free-hub in te back wheel then? So it slipped and as such it suddenly allowed te chain to slip through - hence my problem?

    This bike has about 3000 miles on it. Does this sound like time to start replacing stuff - baring in mind i am a heavy muscular type of cyclist - 16s s0 coudl have had more hammer....??

    Is this an expensive to sort out?

    Thanks, Steve
  • maddog 2maddog 2 Posts: 8,114
    the freehub is located inside the rear cassette and is part of the wheel basically.

    It has teeth inside (pawls) which engage into slots to create drive, and disengage so you can freewheel. Sometimes they slip and fail to engage. In such situations the drive momentarily slips, then grips.

    This can happen ay any time really, but worn freehubs will do it more often. Some freehubs can be dismantled and re-greased and re-pawled, such as Hope. Others can't, such as Shimano. Not sure about Campag.

    All freehubs I know of can be replaced, and they don't cost a fortune. If it keeps doing then think about replacing it.

    If it doesnt happen again then I susepct it was just an icy patch... :roll:
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • PokerfacePokerface Posts: 7,960
    Check your rear tyre. If there is a small bald patch, then it's a good bet that you just spun your wheel!! (There probably won't be one even if you DID spin out).

    But I've also spun my rear wheel out many a time - always going up a hill and always when out of the saddle (as there isn't enough weight pushing the rear wheel down). If the road was wet at all, good chance it was just that - especially if you were out of the saddle.

    It's easy to make it happen again too! Just repeat the conditions. Harder you push down on the pedals from a standing start, or while climbing slowly, better the chances of making the wheel spin!
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