Noisy, `rattley` derailleur jockey wheels

JamesB

I`ve just fitted a new chain which runs sweetly on the cassette (campag drivetrain BUT; removed after one use jockey wheels to clean them. when replaced on the 3 largest sprocket positions the cage `bobbed about` and rattled. So thought maybe jockey wheels were worn after 10k miles + use---there was quite a lot of play in them

So bought a set Tacx pulleys; fitted them and still have same effect but to a lesser degree---large chainring, 3 largest sprockets quite rattley / noisy

Baffled by this, any thoughts what`s going on here?

mercia_man

This has baffled me too, James. Kept my mind quite occupied while I was out on a training run! (on foot).

I had a similar jumping chain on my Campag drivetrain caused by using Muc Off dry lube which leaves a sticky residue which gummed up several links and was really difficult to clean off. Solved by cleaning chain thoroughly and switching to Finish Line dry lube.

But I don't think this applies to you as your problem is only on largest three sprockets.

My best guess is that the indexing is slightly out after fitting a new chain and then new jockey wheels. I'd take off the chain and adjust high/low stops and indexing so that the top jockey wheel tracks each cog perfectly.

My indexing recently went out and I found that the rear derailleur cable outer had jumped out of the end cap going into the mech and was sitting on top of the cap edge rather than fitting snugly inside.

JamesB

Thanks for this; I`ve had another good look at deraileur and it seemed very slightly twisted, so have adjusted twist and readjusted stop screws and it runs a lot better.
I think the considerable sideways play in the old worn jockey wheels compensated for a slight twist but with new ones the twist mattered, it put the chain slightly off line on the pulleys