Originally Posted by
Indycasa
If only the lockring broke, is it possible to only replace the lockring? And if I do this does it matter whether the BB is french/swiss/english?
Yes, and yes. The lockring thread has to match the thread on the cup, which has to match the thread in the bottom bracket shell.
Are there any markings on the
cups? E.g. "1.37 x 24" would indicate English thread; "35 x 1" could be either French or Swiss. Other, more arcane marking are also possible (although less likely for a 1980s vintage bike). Sometimes the knurling pattern on the lockring can indicate thread spec as well:
Source: Sutherland's 4th Edition