Slight pedal slippage

timotie0612
timotie0612 Posts: 13
edited April 2014 in Workshop
Wonder if anyone has any clue on this. When pedalling my Defy 105 I'm experiencing an ever so slight slip on the right pedal just at the start of the down stroke. It is more noticeable when spinning up hill. It feels as though for a split second there is no resistance and then the resistance hits back in again. It only happens on one side not the other. I'm happy it's not my pedalling stroke as I don't experience the same thing when out on my other road bikes. I'm guessing it's therefore BB, crank arm or pedal bearings - has anyone experienced anything similar or any ideas whether these areas can be ruled out or anything else I might be missing??

Comments

  • homers_double
    homers_double Posts: 8,279
    What BB is it? I'm guessing your crank arm was at some point loose and the splines of the relevant interfaces have worn ever so slightly
    Advocate of disc brakes.
  • arran77
    arran77 Posts: 9,260
    homers double wrote:
    What BB is it? I'm guessing your crank arm was at some point loose and the splines of the relevant interfaces have worn ever so slightly

    This would make sense to me especially as you only experience it at the top of the down stroke.
    "Arran, you are like the Tony Benn of smut. You have never diluted your depravity and always stand by your beliefs. You have my respect sir and your wife my pity" :lol:

    seanoconn
  • JayKosta
    JayKosta Posts: 635
    Whatever attaches the arms to the spindle needs to tightened NOW if there is any chance to avoid having to buy new parts, and to avoid a complete failure of the attachment.

    I wouldn't ride it any more until fixed.

    Jay Kosta
    Endwell NY USA
  • darkhairedlord
    darkhairedlord Posts: 7,180
    I had a similar thing last year after an injury. Turns out I was momentarily coming off load on one leg. This caused slack in the chain then retightening.
  • mamba80
    mamba80 Posts: 5,032
    it might be BB/crank, I d have thought you would get clicking or other noise? but also worth checking the rear cassette/freehub, pawl springs in particular, stick another wheel in.
  • Monty Dog
    Monty Dog Posts: 20,614
    Grab each end of the cranks and push-pull firmly in all directions - there should be no movement except around the axis of rotation. If the non-drive crank arm has been ridden loose, it's likely that the splines in the arm have been deformed and you'll need to replace. The BB bearings might be worn/lose but you'd feel that throughout the stroke not at the top. Also check that the pedal is securely fixed - some carbon cranks have a metal insert that works loose. If everything to do with cranks/pedals/BB is OK then I'd suspect your rear wheel freehub.
    Make mine an Italian, with Campagnolo on the side..
  • damocles10
    damocles10 Posts: 340
    mamba80 wrote:
    it might be BB/crank, I d have thought you would get clicking or other noise? but also worth checking the rear cassette/freehub, pawl springs in particular, stick another wheel in.

    I had this same thing, turned out to be a worn out teeth for the pawl mechanism....most annoying and very dangerous in traffic as the chainset would slip under pressure.

    OP should get it looked at by the LBS, coming off is not worth it.

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