Originally Posted by
Specialized2k10
Thanks. Is there some sort of formula for all this? The thing that was throwing me off was that one had a longer TT while the other had a longer seat tube.
There is, a few trig formulas are used. You want to compare the stack and reach between different frames. You also have to account for the different head tube lengths when the other values are equal. There are a few stack/reach calculators on the web that get you close enough for comparisons. There are also many stack/reach articles out there that explain the concept.
http://velonews.competitor.com/2011/...ndustry_154565
http://www.slowtwitch.com/Bike_Fit/C...er_One_95.html
Your frames practically have the same reach. Frame B has a higher stack.