Clicking noise with every 2nd rotation of rear wheel

sorenwrang

Hi,

I am currently experiencing a clicking noise whose origin I simply can't identify. It seems to come from my rear wheel.
The noise sounds like the "cricket" noise you hear when you keep pedaling after attempting to shift to a smaller cog on the cassette but the rear derailleur fails to shift. However, my rear derailleur shifts fine, so that's not the problem.

What really puzzles me is that:
1. The noise seems to be synced to every 2nd rotation of my rear wheel. It is definitely not every rotation of the wheel, and neither every crank rotation or every other rotation.
2. It is primarily heard when I'm in the 4th smallest cog on my cassette.

I cannot confirm nor disconfirm whether the sounds is there when freewheeling or not, simply because the sound of my hub would drown this cricket noise, should it be there.

Do you have any clue what could be the cause of the noise? I am truly baffled - it doesn't make sense that it occurs on every 2nd wheel rotation.

Best regards.

fenix

Something on the chain - are two revolutions of the wheel the same as one rev of the chain ?

Look at the chain going round the jockey wheels ?

sorenwrang

Fenix wrote:

Something on the chain - are two revolutions of the wheel the same as one rev of the chain ?

Look at the chain going round the jockey wheels ?

Hmm.. I'm still quite sure that it's roughly once per 2 wheel rotations. That would correspond to 2 cassette rotations. 2 rotations of the 4th smallest cog is maybe a third of the chain length? So my first impulse is, that it's not once per chain rotation. But I might be wrong - as I said, it is quite difficult to determine the frequency of the noise relative to rotations of various parts on the bike. It is definitely worth inspecting the chain for minor defects. Thanks for the suggestion!

In the meantime: Other suggestions are still welcome !

tonysj

sorenwrang wrote:

Fenix wrote:

Something on the chain - are two revolutions of the wheel the same as one rev of the chain ?

Look at the chain going round the jockey wheels ?

Hmm.. I'm still quite sure that it's roughly once per 2 wheel rotations. That would correspond to 2 cassette rotations. 2 rotations of the 4th smallest cog is maybe a third of the chain length? So my first impulse is, that it's not once per chain rotation. But I might be wrong - as I said, it is quite difficult to determine the frequency of the noise relative to rotations of various parts on the bike. It is definitely worth inspecting the chain for minor defects. Thanks for the suggestion!

In the meantime: Other suggestions are still welcome !

Id be looking at the chain to be honest.
Try cleaning a link and put white tipex on the link so its visible while riding. See if that aids your diagnosis.
I had a tooth on my cassette that was slightly out of line and was causing a weird noise, once I straightened it no noise....

T

sungod

hang the bike up then turn the crank by hand, it will be easier to hear/see what is happening

Bumo_b

With the others on this, would bet on the chain or derailleur as it happens every other revolution as long as it occurs at different times on each pedal stroke.

stefano

I ride to work a fixed bike with 49*18 cogs. I have the same noise every two rotations. I assume it must be one of the rear sprocket cogs. I had this in the past and was the rear cog in need of replacement. I will check today and come back.

Tip: check if there is a hold and release sense this is when the cog is like shark fin, then probably needs new cassette or sprocket...