i thought i knew this, but there is contradicting information all over the internet, mainly from other dudes on forums. someone help me set this straight.
so…
lockring threading matters, so you can’t put a dura ace on a campagnolo, or a dura ace/campagnolo on a mavic. however, the cog threading is universal, no matter what hub. everyone uses 1.37tpi, so you can slam dura ace onto campagnolo, phil wood onto formula, etc.
The sprocket (or freewheel, for geared hubs) is usually ISO 1.375" x 24tpi, no issues unless it’s old and French (1.366"x25.4). There are some slight differences between Italian (1.378"x24), English (1.37"x24) & ISO (1.375"x24, a compromise between Ita/Eng), but it’ll only be a problem if you keep switching from one to the other.
Lockrings are different though:
English/ISO is 1.29" x 24tpi
Campy/Phil is 1.32" x 24tpi
French is 33mm x 1mm