Originally Posted by
unworthy1
can't tell by looking, at least us mere mortals can't. I'm inclined to trust that Raleigh would have spec'd BSC threads, but do you *know* that it's the original wheel? In this case, I'd try a known British lockring or FW and grease it up good before trial. Don't go past the point of hand torque-ing; if it doesn't jam up within a few turns, it's probably a "go". Thing is that the difference between FR and BSC (34.7 x 1mm and 1.37" x 24tpi) is so close you really can't tell by measuring with common tools, and the real crucial difference is in the thread *angle* which you would only see in a magnified cross-section. But you can tell right away if you test it by simple go/no-go trial.
Per the numbers, the diameters are so close that measument errors or damage can obscure the difference, 34.8 (ISO) versus 34.7 for the French. If the French thread pitch is 1 per mm, then in an inch you can count out 25.4, or 25 threads in just less than an inch. This is one less than English. I think that by measuring very carefully with a caliper on both your Normandy and a known English or ISO hub, you can see if there is a consistent difference between the two hubs.
Even better, use the known English hub or an English adjustable BB cup as a thread guage by laying its thread over the thread of the Normandy and see if they nest perfectly. If they don't, the Normandy is French. Your LBS might even have a suitable thread guage that could be used.
I really would not risk thread damage by a go/no-go test.
Road Fan