--- Richard M Sachs <richardsachs@juno.com> wrote:
"...typically, all measurements on a bicycle are center to center. fwiw, measuring the key dimensions after it is assembled will not always replicate the 2D ones that were in the frame blueprint."
Richard, I asume you do, as I and others did and/or do, i.e., incorporate every parts variable into the frame design, i.e., lower stack heigth, tire size, rim radius, etc., such that when it's all assembled, tires pumped up, tape shellacked, and what not, THAT A FINAL MEASURING INSPECTION SHOULD JIVE WITH THE BUILDER'S AIM, ELSE HE ERRED.
As earlier discussed with chainstay length, the "effective chainstay length," as Don called it, or the "virtual length," to paraphrase, as you called it, can be double-checked by measuring the actual chainstay length, i.e., hypotenuse, and add half a centimeter or so, ON AN ASSEMBLED BICYCLE. The third dimension isn't at play here.
The only third dimension measurements that aren't on your 2D drawing of note are dropout spacing and all that that entails.
So if I positioned my newly assembled summumbonumboojum bicycle upright on a level surface, approached it from the side(2D as in your drawing) and went to town on it with my tape measure, I'd expect all my measurements taken by me, someone with basic math skills, to jive with da plans.
That said, what can't I measure with fair accuracy to double-check what the builder promised?
Joe Starck summumbonumboojum bicycles Madison, WI