damnable

Hi everyone,

Another sizing question here. When measuring a seat tube, what is the accepted measurement?

a) Center of BB to center of join with top tube
b) Center of BB to top of seattube (where seatpost is inserted).
c) Center of BB to center theoretical horizontal top tube position (same as a in a frame with a horizontal top tube).

And do frame manufacturers all use the same method to measure their seat tubes?

Thanks

3v1lD4v3

Manufacturers use all three methods. Seat tube length doesn't really count unless you've got an integrated post. Use the Competitive Cyclist calculator to find out what size frame you need and then go shopping by effective top tube length.

damnable

So I should just ignore the seat tube length?

I'm looking at bikes around with a 53cm horizontal top tube. For frames with this length top tube I've found a range from 46cm to 52cm for the seat tube.

halfspeed

With modern sloping tob tubes, seat tube length is a useless metric. You have to look at head tube length instead. Unfortunately, there's no handy formula for translating leg length to head tube length like there is for seat tube. The CC fit calculator will not tell you what you want to know.