Originally Posted by
FBinNY
I think we're well past that and by now he's probably removed the cup and replaced the BB. However, if he hasn't there's a catch 22. Both Italian threaded and BSC BB shells from the same maker have the same exterior dimensions, so you can't just measure the shell unless you measure it from the inside by which time you already know.
Sure.
But removing the left side is sufficient to measure the shell diameter, which tells you what the right side is.