I'm 6'1" and ride a 61c-c (seat tube)x 59 c-c (top tube) with 7 fingers (meaty ones at that) of seatpost showing. Yes, it's a matter of preference, but it's also a matter of what fits. For my height, I've got rediculously long legs and a stubby torso. Some folks, though, would just look at my overall height and put me on a 57. I keep my hbars about 1.5 inches below the saddle (not quite to rivendell spec, but much higher than the trackies) and am comfortable on 100 mile + rides.