I just changed my bike from indoor to outdoor. During the winter I use a different chain/cassette combo (to save wear/tear, and cuz those Spinervals are so damn hard anyway) on my trainer.
In going back to my outdoor combo, I'm running a 12-23 cassette and the chain keeps skipping right on over the 13. Otherwise, my shifting is silky smoothe...just won't stay on the 13 (lg chain ring).
I was having no problems in the fall before I took the cassette/chain off...very strange. How could it seem properly adjusted in the 12, 14, 15, etc. but totally **** on the 13? I can't see any obvious signs of distress on the cog, and it's not on backward (I double-checked)...plus I was having no problems before I took it off.
Cassette was stored carefully in tool box during the winter.