If your going to try to live up to your name crushkilldstroy then maybe you should first do your home work and know a little about current frame & old component design before trying make full brain/smart comments.
The question was how to measure Setback. Measure centerline of seapost tubing, from that point horizontally measure to the center between the forward & rear saddle mounting sections.
It sounds like the question was to try find out the true seat post angle with the seatpost incorporated.
There has been no real standard in todays frame design. A lot of new seat posts are now zero setback because this gives a more true end result for frame designers reaching there ergonomic & balance goals.
By the way, the 16mm setback for the Thomson seatpost is not for their standard seat post which is actually is zero setback. Old campy is 20mm, newer ones measures 25-28mm. Nitto states 25.4 but actual measurement is around 19mm, Salsa is 16mm, Ritchey 20mm, Easton is also different, Kalloy measures 28+mm. 25mm was an unofficial standard but the manufacturers don't follow it, so there is no real standard and varies widely if you measure the effects on the seat post/saddle angle. Setback helps dampen the road.
Most frame makers have designed there bikes with zero setback in mind. If you look at custom frame makers, they will make a zero setback seatost for there customers.
Last edited by mr_macgee; 01-28-09 at 04:55 AM.