lockring sizing?
 

I'm in the process of my first fixed conversion and have run into a problem, er oppurtunity. I'm using the old hub that was on the 87 Peugeot and I am able to thread the cog on but I can't seem to get the Dura-Ace lockring to thread on. I checked the threads and they are the same, but I think the lockring is smaller than the diameter of the hub. Is this possible? Thanks in advance for any help.

You are using the wrong lockring. The lockring that you are using is meant for a track hub, whihc has a smaller diameter thread and is reverse threaded.
You need a Bottom Bracket lockring, which has the same threading as your hub.

Doh! Thanks B.

Personally, I'd skip using a BB lockring- and use turbocharged Loctite- since the loctite will actually hold better than the ring. The BB loockring seems to promote a rather false sense of security. There is tight, and then there is TIGHT- plenty of people around here seem to strip and spin off cogs using proper track hubs.

Though on the suicide setup, I'd use both!
and loctite the lock ring, too.