Just installed brand new chain and derailer on my 2 x 9 set up. All the gears are running fine apart from when the the chain is on the largest cog on the front and the largest on the back.

The chain is rubbing against the lower jockey wheel which is causing lot’s of vibration and noise. Basically the chain is not running centre to the wheel. How can I fix this?

Thanks

you shouldn’t run big to big anyway really.

but check the B screw too to make sure the jockey wheel isn’t hitting the cog.

How can I fix this?

Don’t use that gear combination.

check the B screw too to make sure the jockey wheel isn’t hitting the cog.

+1, pull the mech back while your doing this, to avoid the screw(head/thread) disintegrating as you try to screw it in.