It doesn't appear to be changing gears. It's jumping on the middle ring like the teeth are badly worn and it's slipping. If we really make it slip badly, we can have it fall into the smaller chainring. But with just slightly too much pressure it stays right on the middle ring and jumps teeth. The problem is that I can't clearly see the problem from the captain's spot and have been schooling my wife on what to look for. This cannondale frame is a brick, and the chainline measures like it's in the ballpark. So I doubt that it's frame flex. I also had the front derailler trimmed so the cage was centered nicely about the chain.

The chain measures fine like it isn't stretched. The teeth on the crank look fine. I'm buying a new middle ring in hopes that it goes away.

I was also in the middle of my 9-speed cassette when starting as well. It doesn't happen in a similar gear on the big ring either.


Sheldon