Originally Posted by
rekon
Thanks for sharing your experience. Do you ride a 51 now? If so, how much seat post did you gain with the smaller bike?
My CX bike is getting a new custom frameset that's being hand-built as we speak. The new frame will measure 52cm center of BB to top of seat tube. I will have about 14 cm of seatpost showing (up from 12 cm before). The builder actually proposed a 50cm, but I had him increase the seat tube 2cm to make it easier to shoulder the bike when racing. If I was just going to use it as a gravel grinder or commuter, I would have gone with the 50cm.
But the big improvement is the reduction in reach (effective top tube length) which will let me go from a 60mm stem to a 90mm stem. IMHO, reach (and stack) are the key dimensions you want to get right when sizing a frame. Once you have those dimensions right, whatever seat tube length you end up with to get there can generally be made to work (since seatposts support a relatively huge range of vertical adjustment).