Originally Posted by
spiker
I've got a 63cm, 25", 251/2", 271/2" & a 69cm. The 63 has a roomier cockpit than the 69. Both have 22" top tubes & the same size stems. Last week I put them side by side on a bike rack. The 69 has real laid geometry, the 63 more upright. I didn't bother measuring it but it was qute clear that the geometry had an effect on cockpit length.
Just wated to through another variable into your sizing equation
it has everything to do with it. Many bike fitters will tell you all that matter is stack and reach when comparing frames for sizing. Reach is a measure from the intersection of a vertical line with the TT (or virtual TT) drawn through the BB. Why is reach more relevant? Because it doesn't matter what your seat tube angle is your saddle will always be in the same fore/aft position relative to the BB for your optimal power and efficiency road bike fit and on some bikes that may mean a zero setback post and on others it may mean a setback. In fact, I cannot comfortably ride my vintage steeds for an appreciable length because being tall I require a zero offset seatpost and I can classic record on my two vintage steeds.... I also quickly learned that my shoulder problems were a result of too much length.. I always used a 120mm stem on 58-59cm TT bike with a 25mm setback post because I someone once told me I should ride that... Now I ride with zero offset posts and with a 58cm TT I need a 110mm stem... I'm about 6'3.5".
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear