I've cross-posted this to one of the fixed gear lists, as I believe there's crossover of only a few souls; hope this isn't a problem. Also, please forgive me in advance for the long description of a technical problem that follows:
I've long had an old (early 1980s?) Gipiemme track hub kicking around my parts boxes and last week had it built into a wheel using a NOS Mavic GL330 rim. The hub is stamped "Special ISO", which refers, I assume, to the International Standards Organization. Although the hub had been lightly used before I bought it, both the wheelbuilder and I thought the cog threads to be clean and deep, and when I hand-threaded a Suntour track cog onto it without using grease It seemed to fit fine. The lockring threads were slightly marfed, though, and I couldn't thread on a new Dura Ace lockring. In fact, it seemed to be too small in diameter, and I assumed that the ISO threading must be different from garden-variety. Is this so?
Last night I finished the build on my Masi fixie and applied a little torque through my legs to get the cog to seat--and it freely spun away. Not when I was applying back pressure, mind--this was while pedaling forward! I was late for a ride and so grabbed another bike and still haven't assessed the damage. Is it the case, though, that ISO cog threading is almost exactly the same--but just slightly of a smaller diameter--than standard? If so, and assuming I haven't trashed the hub, are cogs and lock rings available anywhere?
If I were Sheldon I'd insert here the quote that says something like "the great thing about standards is that there's so many to choose from". Of course, if I were Sheldon I wouldn't have (likely) trashed my beautiful new wheel.