Merckx titanium with Chorus, Columbus Cyclops Campy Victory, 531 Harry Quinn 1st gen DA, SLX Fuso 8-spd DA, Airfriday. Colnago Gilco with Campy mix, Claude Pottie 753 w. 8S Record, Claude Pottie Columbus with 105, Basso with DA 7402, Masi Team 3v wit
Changing ST-to-TT ratio question.
As I look at my list of some two dozen frames (don't ask why I have two dozen+ frames), I notice that ST to TT ratio seems to increase as the ST size increases.
So, a 50cm ST frame typically has a TT greater than its ST (TT = 52, even 54cm),
then when I get to the middle of the pack (ST=56 or 57) the TT matches (I think this is called "Square"? as in "a 56square is a 56STx56TT) then in the bigger frame sizes the TT drops down smaller than the ST (so a 62cm ST frame has a 59 or 60cm TT)
This can't be based on body dimensions.
Is there some constraint in framebuilding that makes this change in ST:TT ration change so?
I'm not sure I buy that. Obviously seated people are half the height, so half the variance, but that assumes the upper body range difference is the same as the bottom.
I had three reasons, but they were just guesses, I'm not convinced. One is based on the idea there is a cycling type who in performance male version has long legs and smaller upper body, lots of power to push, but no more upper body weight than necesarry. Two, the idea is that the tubes are fixed length so they run out of materials in the longer sizes and there are constraints, but since tubes are available in a variety sizes, seems unlikely. 3, is the idea that there are certain markers that buyers are looking for like a wheel base length or frame weight, and the longer sizes get squeezed. If a big guy can get onto the shorter top tube length, maybe he wants the more nimble wheel base.