I would throw this out there: There is virtually NO difference between a 700 C rim (622 bead diameter, 311 radius from fork to ground) and a 27" rim (630 bead diameter, 315 radius). The difference is 1.5%. I'm pretty sure I could not detect a difference, and confident that that vast majority people, perhaps all, could not. I think the differences that people are talking about come from wider tires that are common with 27s that look like racing bikes.