Originally Posted by
seadboy
No, mostly, I use the big one,
The teeth don't lie
If you mostly use the big one how did the middle teeth get so worn?
edit: In your OP you said you had a problem with skipping and then you changed your chain and cassette. Normally if a chain and cassette wear together they will not skip until you change the chain. Did you change the chain and cassette at the same time?