On a somewhat related thread hijacking note I had a strange experience with shell width. I inherited an old frame from a friend of mine and the bottom bracket was trashed. Sounds easy enough to fix right?

The first thing I did was remove the BB. As I was unsure of the threading of said BB, I had to be very careful. It turned out it is right hand thread on both sides. OK next step, measure the width of the BB shell, 68mm. Aha, French threading, this sucks. Spoke with the kind folks at Harris and they let me in on a way to install one of the older Shimano un-73's with Phil French BB rings. When I got home to install it the rings were far too small. Obviously not French.

It turns out that at some point one of the previous owners of said frame stripped the BB threads and had it rethreaded Italian. In the end learned that I have a very unique 68mm wide Italian threaded BB shell.