I'm thinking of giving fixed gear a go on my single speed bike. Due to shortages, parts are sort of expensive and I'm thinking of sourcing cheap parts, i.e. take whatever fixed wheel I can get and order a simple cog from somewhere. However, I don't know if there are different threads/sizes/standards for the cog and/or lockring.
Sheldon Brown has a comprehensive article about fixed gear conversion that includes the list of different threads. To summarize, there are three different lockring threads:
- English/ISO 1.29" x 24 TPI
- Campagnolo/Phil Wood 1.32" x 24 TPI
- French 33 mm x 1.0 mm
Sheldon Brown calls the French thread "old French" but current Mavic track wheels are still using it. There are also two different cog threads, ISO and Italian but their difference is only 0.3mm in diameter. In principle mixing the standards increases the risk of stripping threads, but in practice they are cross compatible.