Helping out a kid whose bike is wearing though the inner cage. SRAM GX.
Mech hanger is straight.
Any ideas what this could be caused by?!?
Pic of wear
Chain has slipped off the pulley and been running between the cage and the side of the pulley.
Yup, the chain has been doing some time off one side of the jockey wheel. It won't take long to wear the cage like that. Probably best to clean it all up, put a new cage on and get the limits, b screw and indexing spot on.
Ta both. Seems to make sense. Told him to buy the cage and will set it up from scratch 👍
Don't know if it's common, but I helped a kid the other day try to sort his GX AXS mech - jockey had got knocked when he was getting it out the car and had come off the bearing completely. He had to lever it back on (I refused to touch something that expensive belonging to someone else!) but there was still a definite wobble to the jockey. I think that could be easily enough to do similar.
From a good look at it, I think the b-screw was/is miles out. So in big cogs, the chain was being derailled down the side of the derailleur cog and wearing through the inner cage.
As always with these things, it's 32 quid for the cage (plus cogs) or 35 quid for a lower grade entire mech... 😔