Chattering Rear Mech

ajkerr73

Measured chain stretch yesterday and it was showing ready to change (0.75) but not "over-stretched".

Changed the chain (same type of chain as before).

Out this morning and I'm getting rear mech "chatter" when working hard in the small ring.

Chain seems to be meshing perfectly with the cassette. It just seems to be noise rather than anything effecting the power transfer.

Cassette and rear mech are both the same age (~5-6000km). Would be surprised if its jockey wheel wear.

Its a medium cage Ultegra mech if that makes any difference.

Any ideas?

redvision

Might sound silly but are you sure you have threaded it through the rear mech correctly?

If so, check the mech hanger is straight.

jermas

If it's a Shimano chain, they are directional- so only run perfectly if installed correctly. The name plate and chamfered edges on the links should face outwards.

arlowood

Could possibly suggest you need a new cassette.

Received wisdom is that if your chain has stretched then it will have impacted on the profile of the sprockets. When you fit a new chain that sprocket wear will be evident with chattering or other running issues

gethinceri

"Received wisdom is that if your chain has stretched then it will have impacted on the profile of the sprockets."

Suggest you try and receive some other "wisdom".

ajkerr73

Looks like it was just a simple indexing issue.

I'd only experienced noise from the cassette before when indexing was out. Noise from the mech was new to me.

Now I know!!

Cheers