Originally Posted by
Steamer
Interpreting again, I think you are saying the return side chain is hitting the chain keeper. If it is hitting the top of the keeper, then the keeper is too short and probably needs to be replaced. If it is hitting the sides of the keeper, then trying adding a washer or two between the idler and the keeper to give it more lateral clearance for the chain.
I would be interested to know what Lightning says /said.
Replying to my own post here....
Reading the OP's last post again, is it the power side chain that is hitting the top, outside of the keeper? Can the holes in the keeper be elongated so it can be dropped down a little bit?
Does this only happen when in the smaller chainrings?
Maybe a smaller diameter idler would help. Can't go too small or the return side chain might hit the fork crown.
The bike in the pic looks new. If so, I'd be contacting Lightning and having them provide the fix.