You can bet on it. A "medium" RD is more like a long-cage. The "long-cage" you see - rarely - are really long and designed for all-out mountain-bikers. Mediums will handle most situations. And Shimano shoots itself in the foot by saying 27T is maximum. Nonsense. I run Ultegra RD's and have seen them easily take on a 30 - 32T in the rear. Apparently the max-size is referring to the largest size in that particular gruppo.
Shimano discourages customers in this way, and the max-size they list should be ignored. I just installed a FD (Shimano) that was max at 44-48T (FD-M961). I put this on to work with an Ultegra triple - 30-39-52. It has plenty of room to spare and shifts flawlessly.
Wake up, Shimano!
Last edited by Panthers007; 02-22-09 at 06:56 PM.
Reason: Syn