I don't get the whole need to face the BB shell for external BB. Isn't the alignment of the BB dependant on the shell threading, not the face of the BB?
Interesting point. I can only assume that once you tighten up to 35-40Nm, the threads deform enough to allow the cup face to sit flush against the bb shell, thus putting the bearing at a slight angle.
I don't get the whole need to face the BB shell for external BB. Isn't the alignment of the BB dependant on the shell threading, not the face of the BB?
Am I just complety confused?