Originally Posted by
datlas
Update: I put bike on stand. Chain has ZERO stretch in it. Cassette and chainring do not look worn. I put in big/big and tried to get it to skip, and could not.
BUT...a clue? I noticed on big/big, when I back-pedal, within a few crank turns, the REAR goes to the 3rd largest cog (ie shifts over two cogs). The drivetrain does NOT seem to like the sideways deflection from cross chaining. I get that but this did NOT happen before.
Any ideas?
Worn chain or too much chain tension on big-big. (= too short)
Edit: or both. By "worn" I mean there's side to side play on the chain and the excess tension pulls it off the sprocket.