[ACF]

13", 15", 17" etc.

What is being measured to come up with those numbers?

 

[mrbigisbudgood]

Originally posted by ACF
13", 15", 17" etc.

What is being measured to come up with those numbers?

Seat tube length.

Depends on the manufacturer as far as method of measurement. Bottom bracket center to top tube center - bottom bracket center to top of seat tube - top of bottom bracket to top of seat tube. The method of measurement should be standardized IMHO.

If your trying to figure out what size you need, ride it. Unless you know what number you like to see on a frame, you need to ride the bike to check the fit.