My crank has a little slack and cracks more and more when I pedal, but only on only with the left pedal.

What could be the cause(s) of this ?

Video of the loose crank:

Video of the cracking crank:

  • By "cracks" do you mean "makes a sudden sound", "fractures" or is it a typo for "creaks"? Sep 1, 2016 at 8:20
  • 2
    I suspect that your "crank" is loose on the crank shaft, if this bike has a 3-piece crank. This can rather quickly destroy the crank, so you need to get it tended to pronto. Sep 1, 2016 at 11:45
  • Thank you Daniel, its louder and louder so I'm afraid you are right
    – Pleymor
    Sep 2, 2016 at 19:13

1 Answer 1


If it is an older 3-piece crank, and if you feel play on the left-side downstroke, then it could certainly be a loose cotter, but it could also be that the bearing cap needs to be tightened in a tad more. I have an older 3-piece crank (w/ loose ballbearings) and I've had to do that before, especially after an overhaul when things tend to loosen up after a few rides.

Of course, there are many types of bottom brackets, as explained here:


  • I'll record a video of my problem and then check your hypothesis, so that it can be useful for future diagnosis. Thanks !
    – Pleymor
    Sep 2, 2016 at 19:15
  • It was the left crank which was damaged with time, and needs to be changed because it is very loose and can't be tightened anymore (30yo bike)
    – Pleymor
    Sep 3, 2016 at 8:59
  • @Pleymor - If the crank had been tightened when the symptoms first appeared, it likely could have been saved. Sep 3, 2016 at 11:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.