I am pretty good at indexing my gears and bike maintenance but am stumped by a problem I have never seen before.

Lent my hardtail to a pal who was doing a 3 day ride and it has come back with a bent chain!! He does not know how it happened but suspect it came off going down hill and he has powered on and damaged the chain. He made a trailside repair and finished the ride but chain will have been too short for the latter part of his trip.

I have now replaced the chain and find that the front indexing and rear indexing are faultless on the work stand but when under load the chain jumps on the 3 smallest cogs on the cassette. I thought a worn cassette, tried another wheel, no good. I wondered about a indexing problem I had not diagnosed so disconnected the gear cable, still got the problem. I wondered about a bent derailleur so tried another one, same problem. The limit screws are set correctly.. I am lost.

Its an Orange P7, with XT mechanicals on a Hope Pro 2 hub…

check that the rar mech hasn't been knocked or pulled out of alignment

I bent a mech and hanger when a chain came off. Have you checked the mech hanger? Assume as it's a P7 it's steel and can be bent back?

Assuming you've fitted the correct type of new chain, sounds like a worn cassette not mating properly with a new chain, was the other cassette you tried also a used one?

bent hanger? i had this turned out the hanger was slightly bent allthough it looked ok by eye

Bent rear hanger?

Could well be worn/damaged chain rings – sounds like you've ruled everything else out

Hi All…

Thanks for the input…I am pleased you guys are stuck too. I tried an older Shimano chain and wondered if the age of the chain was the issue, tried a new sram chain and still the problem is there. I have a hanger tool and although the rear hanger was a little out I have solved that. I am wondering if the bike is bent? I am running out of other ideas…. 😥

check the hub for pawl/engagement ring damage, those 3 smallest cogs put the most strain on the engagement system.

Loosen the cassette on the wheel and tighten again? Maybe its shifted a bit as on some cassettes the bottom three cogs are seperate from the main body and might have mooved?

Had a similar problem and everything looked spot on, ended up buying a whole new drive train. thurned out to be a very small amount of play in the rear mech hanger. New hanger and bolts and it was fine.

long shot but' bent hub axle? try another wheel/cassett

My slippage on a hope pro 2 hub turned out to be a split hub shell!! It would engage under light load ie a work stand but under any real load….
Its been sent to Hope who have said that they will replace the hub body under warranty.