"HBW" <
[email protected]> wrote:
>I'm trying to figure out what size frame is best for me. I'm 5'9", 165 lbs with a 31" inseam.
>Thanks to anyone who can at least give me a range.
Frame "size" means so many different things to so many different builders that it can become almost
meaningless.
To some (like me), it's the distance from the bottom bracket to an imaginary line drawn from the top
of the top tube through the center of the seat tube. That tells you how high the top of the top tube
is, which is what you really need to know. This method is referred to as "center to top".
Others measure "center to center", which tells you where the center of the top tube is. That's a
nice thing to know if you're designing the frame or mitering the tubes, but the rider really
shouldn't care where the center of the tube is (except to compare to another frame that's measured
that way). You can usually add ~1.5cm to this number to get an approximate center to top equivalent.
Other (QR used to do this - I haven't checked whether they still do) measure to the top of the seat
tube. This is one I've never figured out, except that it's handy for helping you estimate how much
seat post will be showing. However in terms of comparison to other bikes, it's a worthless way of
measuring a bike frame (IMHO of course).
The most important thing with bike fit is getting the "cockpit length" right. Once you've determined
that, you can look for frames that will accomodate your necessary top tube plus stem length, and
determine which (if any) you can comfortably stand over.
Keep in mind that the steeper the seat tube angle, the taller the frame for a "given size". That is
to say, a 54cm c-t tri bike with a 78 degree seat tube is considerably taller than a 54cm c-t road
bike with a 73 degree seat tube - at least if you assume they have the same bottom bracket height...
but that's a topic for another thread.
Mark Hickey Habanero Cycles
http://www.habcycles.com Home of the $695 ti frame
