I have a nice Mavic rim laced to an old Shimano Uniglide 7 speed hub. I'd like to throw it on a bike for single-speed use (obviously not fixed gear because it's a freehub), but most of the spacer sets I'm seeing a designed for modern 8-9-10 speed hubs. Are the splines on my uniglide hub different, and if so, do I need a different kind of spacer?

Also, I know that the small cog is threaded on this hub and serves as a lock ring. Is it possible to get a threaded lockring, or do I just have to use a spare 12t cog as a lockring? Thanks in advance...

I don't think that most (or any) spacers are splined anyway, but uniglide splines are the same as hyperglide, it's just the lock-ring that's different. On uniglide the smallest ring <i>is<i> the lockring, which may look kind of silly, but will work fine. If you don't like it, you could just switch out the free-hub body to hyperglide from a trashed wheel.

Lastly, some freehub bodies were both uniglide and hyperglide compatible, check to see if yours is, and you might be able to use a regular lockring.

this part is wrong. uniglide and hyperglide have different splines.
Hyperglide cogs have one wide spline and will not fit on a uniglide freehub unless you file down the spline.
(uniglide cogs will fit on w hyperglide bidy though)

you can use most spacers (or some PVC pipe) and yes, you'll need to use the small cog as the lockring.

I was afraid I was going to have to hunt for some obscure uniglide-specific kind of spacer. I'll stop by my LBS for some spacers then. I was kind of hoping that I could get an actual lockring that wasn't a cog just for aesthetics, though... not a big deal. Thanks for the help!

You're right, I wasn't really thinking.