dddd

Wow, this thread is chock full of information, lots of good info! Definitely one of the best discussions on this subject I have ever come across.

Thanks especially to Doug Fattic for chiming in with such a clear explanation of generating complete bike frame alignment!

At one time, I modified a crankarm by extending it and adding a bent-wire indicator. I decided that (with my inability to confirm the accuracy of both the threaded bores and faces of the bb shell) I should only reference off of my as-installed, symmetrical 112mm bottom bracket spindle.
This was when I was developing my Pedersen race bike, on which I had to move everything around quite a bit, starting with spreading from 114mm to 130mm, increasing rear tire clearances, aligning seat tubes and then the front end. I would eventually break it in a couple of places while racing, but left repairs to professionals like Hugh Enox and Steve Rex. It still rides straight today.