Originally Posted by
veryredbike
They could do it by top tube, sure... but that only tells you part of it, even for the most basic fit... what about the head tube height? More and more I'm coming to discover that that's a variable that I need to pay more attention to. In the end, the V-top tube length doesn't tell you that much more than the faked tube length.
Like massive is saying, if you want a number that tells you if the bike fits when it comes to production bikes, it doesn't exist.
Actually, now I cast my mind back to when it first started bnothering me, I recall thinking the head tube length was probably the next most important thing to specify (chainstay length, BB drop, head angle etc are more about handling than fit), although stem angle gives you some leeway...
Effective top tube length and maybe head tube length is info I'd much rather see when I'm browsing second hand frames, for instance...