- They need to be the right width (OLN dimension) for the frame yr thinking of using them in. Track frames are 120mm at the rear. Modern road frames are 130mm, older road frames are usually something in between these two. Most track and road frames use 100mm hubs in the front.
- You need to get a rim with the same number of drillings as the hub. 700c rims (ie track/road bike size) are easy to get in 32h or 26h drillings - other drillings (eg 28h, 40h)are available but you'll need to look around a bit.
- It helps if the hub is threaded for both a cog and a lockring. If its only got a threading for a freewheel like a typical BMX hub then you need to do a search on 'suicide hub' on google / these forums. Its still fixable but there may be safety issues you need to be aware of.
If you re space the hub out to properly fit your frame yes. My winter beater wheels are a pair of ancient Shimano BMX hubs. I know I know! its a sin, but hell they work and theyre as old as me!
A track cog will thread on no problem to a bmx hub, if you plan on riding in the city alot, or like me, dont bother useing the brake long enough that it seized throw a little blue loc-tite on the threads. If that still makes you nervous BMX hubs have almost double the amount of threads a standard hub does. You can add a BB loc-ring to help snug it all up.
It may interest you to know that many of the more "serious" (hate using the term in the case of bmx, but hey, whatever) freestyle bmxers are switching to 36h hubs, while bmx racers have been using 36h hubs for years, so it shouldn't be an issue to find a wide selection of 36h hubs.
Also, if you're looking into a GSport hub, make sure you get the Marmoset, because all the other hubs use a 9/16" bolt, which I can guarantee won't fit your track frame or fork without significant grinding.