Originally Posted by
toytech
the ring is a 42, and you are correct, all the rd are 9speed. all but one fd are marked 10speed.
even better...
the rear derailleurs without the traditional b screw are late 9/10 speed. the ones with the b screw are 8/early 9 speed.
in my experience, a 10spd front should work with 9, but a 9 doesnt work well with 10 unless you add the nylon wear plate. (without it the cage is too wide and the shifting is finicky)