There are some differences between the RCS and CCS frames, but my impression is that as far as sizing, there is no real difference. So I can tell you that as a 5'10" person, the L frame is just OK. I kind of think I'd have been better off with an M. I'd like to have the extra inch of stand-over. The L is OK for me in that department, but not a lot of room to spare. This would depend a lot on your inseam rather than height, so I should say I have a 32" inseam. My brother, who is 6'1" but has a 31 inch inseam, would definitely prefer the M.