Somehow missed this during the original go around, so I am dredging it up again. I know its not something your normally going to go after but it seems to me you could check head and seatube twist with an angle finder, frame chucked up in vice, check each tube and voila in degrees easy peasey. Might be good to know when the frame doesn't respond to the alignment as expected and its off mare than a bit.
Originally Posted by
gugie
For those wondering how I did this, there's no magic.
Check all the joints for cracking. In this case the brazework looked top notch. Find where the worst bend is. In this case, you can easily see it from the pictures. Measure how far the offset is, using the string method (least accurate), a frame alignment gauge like I did (more accurate), or a framebuilders flat table (most accurate). I've checked the alignment gauge against a flat table, at most I'm 1-2mm off of perfect. The one thing I can't check is twist between the head and seat tube.
Next, clamp where you want the fulcrum to be. In this case it was obvious - there was a kink right at the brake bridge. So I clamped right above that and started with a small tug, check to see if it moved, and increase the force a bit at a time so you don't overshoot. After every step I check the dropout width, centering of the dropouts on the frame, and straightness of the stays. Rinse and repeat until the stays look good against a straightedge. Once everthing looks straight, focus on centering, then put the mojo to work on dropout parallelism.
Fancy way of saying just bend it till you like it. And, pics, so it did happen!