This has surely been much discussed, but you wouldn’t know it from my everyday experience. Proper spindle length calculation almost seems like a mysterious secret held within the BMG (Bike Mechanics Guild). I’ve never gotten a straight forward answer to this question from a bike mechanic, but then again, maybe I was asking the wrong mechanics.

I know there are many complicating issues involved with the correct answer; but the essential issue seems to me to be achieving a straight chainline. So I ask, in order to determine the spindle length for a blank-slate frame, what is your method?