Running 2 x 10 X9 and recently bought a new chain – KMC X10-93 to replace the original sram which had stretched. Fitted it yesterday and it shifts fine in the stand. However on riding, it’s ok in the big ring but in the small, particularly using the larger sprockets when climbing, it’s clicking and feels really rough. Got home, took the chain off and checked for stiff links but seems fine. Checked I’ve routed it correctly through the derailleur and that’s ok. Made sure the missing link is engaged properly and again it shifts ok in the stand but is rough and clicking when riding in the small ring again!

Any ideas?

New chain and old cassette = bad / noise. Luckily it sounds as though it’s just noisy and not jumping.

Chains and cassettes wear together (rings do too but generally slower).

Not much you can do really except shove a new cassette on.

Sounds like wear in the drive train to me mate. Might need new cassette/ rings.

Wait for others to comment first though but that’s my guess.

+0.75 (ish) chain wear=new cassette

Ok cheers. I did wonder if that would be it and a new cassette might be in order. Just wanted to make sure there wasn’t anything else obvious i’d missed before forking out.

As above, new cassette required.
Or, if there’s any life left in the old chain, put it back on until you get around to buying a new cassette. Then put both new parts on together. Don’t leave the old bits on too long, though, or the long, old chain’ll start snapping and/or fubar your rings.

When you buy a new chain, you buy a new cassette.

Used to be a shop mechanic, and i’d very very rarely find or have a good reason to do one without the other, and I must’ve done several hundred.