Hi everyone,
Thanks for the many responses above. I have some additional information:
-The cassette, free hub, and chain are all brand new - never been on the road.
-The chain is a KMC Z51 RB. The box states that it is compatible with 18, 21, and 24 speeds.
-The derailleur cables are a couple months old.
-I tested out the shifting. It is fairly crisp on the larger sprockets of the cassette. The chain runs fairly smoothly (apart from cross-chaining) on the larger sprockets.
-The shifting becomes a bit less crisp as I shift into the smallest 3 sprockets.
-I turned the low limiter screw on the rear derailleur as far as it would go clockwise.
-Even after adjusting the limiter screw, when I shift into the smallest sprocket, the chain immediately jumps off the cassette and wedges into the frame.
Here are my questions:
1. Based on the above what is the likely problem causing the chain to jump?
2. Someone above suggested the problem could be the chain is too long. Suppose I cut off another link. Suppose further I had in fact measured the chain correctly at the outset. Can I repair the chain by just adding an additional power link?
3. Is the mix of a SRAM power link and a KMC chain a potential problem?
4. Someone above suggested my high limit screw needs to be adjusted. If I adjust the high limit screw, won't that mess up the shifting to the larger sprockets (which is fine).
Thanks!