Thread locking fluid on fixed cog I just recently got a single speed with a flipflop hub and got the bike shop to switch it to the fixed cog.  While riding around, the gear came loose on the back hub and almost flung me off so I had to bring it back to the shop to get them to tighten it.

Does anyone use any thread locking fluid on the rear wheel gear to keep it from slipping on the hub or will tension from the lockring keep it secure enough?

And if anyone has used thread locking fluid, did they have any problems getting a polymerization reaction to occur due to a low electrochemically in the hub/cog due it being made from aluminum or some other lightweight material?
If you have a fixed gear type hub, not a dual freewheel flip flop hub, and a lockring which is properly installed, there is no benefit to using threadlock on a fixie hub. 

Thread lock works just fine on aluminum, although it tends to cause stripped fasteners because it requires more torque than most aluminum fasteners can handle. With a fixie lockring, though, there aren't enough threads (surface area) to really benefit from a threadlocker.