Originally Posted by
mconlonx
Should be easy enough to mount up a standard road 10sp cass to check things out.
If the cassette does not appear to be completely true, it could be the freehub body which is the issue, not the cassette. Again, mounting a standard road 10sp cass should make this apparent or not.
Finally, we had issues in the shop adjusting early run Tiagra running gear until we were told by Shimano Tech to swap out cable housing ferrules from plastic to metal.
Good luck!
He'd have to get another hub/wheel. The freehub body is different.
He can always measure the space from cog to cog. Shimano 10-speed is 3.95 mm whereas 9-speed is 4.35 mm. I wonder whether the smallest 4 cogs are biased towards 9-speed -- from memory the 9-10-11-13 Capreo cogs are "special" -- whereas the largest are 10. There is usually enough play in the derailer to accommodate some error.
I think the OP's best best is to talk to the cassette manufacturer before doing anything else.