when sizing the seat tube length for traditional (i.e. not compact geometry, not pursuit) track and ss frames?

i can't understand how this measurement even matters? it doesn't provide precise information regarding stand-over height. center-to-center is a much better indicator in my opinion. two different frames could have the same c-c, while having different c-t measurements, right?

why is c-t so popular?

just another way of doing things. it's like pants. a 30 to some is nowhere near 30 in other makers.

it bugs me more when it comes to people selling used frames.

It measures actual seat tube length, so if you use a small frame and want an aero or fluted seatpin you might not be able to tell if it would fit, depends on extension of seat tube past the top of the top tube, if at all. On alloy and carbon frames it can be vital to know this as they have a greater extension past this joint.

unrelated, but have you checked the keirin frames that strattond is selling? His name on Myspace is ichiban and he's got a few in your size I think...

hahaha thanks. that's partially what spawned this post - his ebay titles are all c-t sizing.

thanks for the headsup. i'm unfortunately not in a good $$ situation right now.

When it comes to sizing ctt and ctc are irrelevant except in knowing whether or not you are going to bump your privates. Since seatposts are thick enough and strong enough now to extend 300mm and more above the seatube, the best measurement for how the bike will feel is the virtual top tube. You can raise and lower your seatube dramatically, you can even leave a threadless stem long and use spacers to add length to a head tube, but you are limited to changing the length of the cockpit by two small means, stem length or seat position, and in changing either you are signifcantly changing other parts of the ride.

But that's just me thinking.

Good points, but you can only lower a seatpost so much. Even if the toptube fits, there is no way I could ride a 65cm frame. Plus, the seat tube size generally follows the top tube size, so it is a good estimate of sizing. But, like you say, fine selection should be done at the top tube.

+1