Originally Posted by T-Mar
Yes, they are marked, but you have to know the codes. Here are the Regina codes:
ISO - 3 grooves on back
English - 1 groove or F.I. stamped on back
French - 2 grooves or F.F. stamped on back
Italian - no grooves or stamping on back
ISO is marginally different than English in diameter (0.005") but completely interchangeable, so consider ISO and English to be standard.
Thanks, very helpful. The one I bought as an italian threaded seems to be just italian since there are no grooves or stamping on the back. The freewheel I was asking about has 1 groove on the back which must indicate english threading.
I've read somewhere that if you use a english threaded freewheel on an italian treaded hub you should not go back to italian threaded freewheel because the threads on the hub gets a little damage and there will be a risk of stripping the threads on the hub if you fit a italian threaded freewheel after the english treaded. Is this just in theory or just if you are a strong rider that apply much force to the threads?