Mark, great tips, but I think where the seatube and the plumb drop to the bb aren't a 90 degree angle that my trigonometric table doesn't work. The angle at the ground is the correct seattube measurement, but if the toptube is parallel to the ground then the inside seattube/toptube angle is identical. You are correct about the saddle positioning. I recently have been riding longer seattube bikes with toptubes that are relatively short. I've found that while the seattube and seatpost could be viewed as just an extension of the measurement, in fact, most builders built the longer seattube frames with a shallower angle. So, my previous 53cm bikes, which mostly have 74.5-75 seattube angles, had the right setback; but, the 57cm Chris Kvale has a 73 degree angle. The changed measurements have forced me to buy posts with little or no setback, although in the Kvale case, I just shoved the saddle as far forward as I could on a 27.4 Amercan Classic post that Karen Rawls sent me (thanks Karen). Thanks for the tips. Lou Deeter, Orlando FL