I feel a “pulse” on the beginning of the down stroke on the right side. Can’t really feel anything when the bike is in the stand or at low speeds on the road.
BB is a square tapered. Recently serviced. There does’t seem to be play or noise in the BB itself. I installed new pedals hoping they were the cause.
Like you can see in the video, all three chain rings have a wobble. So I don’t think the rings are bent. Could that cause a pulse when the chain is under load? The chain isn’t rubbing anywhere though.
Is the spider warped (is that possible?). Or is the interface between the spider and BB crooked? I feel like it’s tight enough. Maybe when servicing the arm is mounted in another radial angle than before and because it’s old, it has developed an offset? Should I try and find another rotation of the 4 sides of the axle until I find a better mount position?
Oh, and they’re not biopace rings. They’re not oval.
Wobbly chain rings or crank cause for a “pulse” when pedalling?
byu/Raspieman inbikewrench
by Raspieman
4 Comments
I would say, despite the BB being recently serviced, it’s probably a bent BB Axle. You might be able to see this if you take the cranks off and spin the Axle, or perhaps mount the crank in the opposite direction and see if that makes a difference
Right crank probably bent or misaligned on square taper. Probably it’s right pedal. Try removing right crank and rotate it 90° on spindle for better installation without wobbly chain ring. You can test it without full tightening. Left crank should be rotated as well, if you rotated and reinstalled drive side crank. Probably you need new crankset if it’s bent. Also I would try to replace pedals and see if it was problem with them, before trying to replace cranks.
Try removing the cranks and placing them 180 degrees on the tapers. This may reduce the wobble.
Try all four positions on the square taper. Almost always one position is better than the other 3.