its a bottom bracket lockring. can also be used as a lockring on a suicide hub if you're into that sort of thing. mystery solved.
that is exactly right.../\/\/\/...what he said...
@Wingedangel started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
that is exactly right.../\/\/\/...what he said...