What should I use to tighten a lockring on my fixed wheel? I see many people using locktight. Should I use the red permanent or blue removable kind? Also, should I apply it to both the cog and lockring threads or just the lockring?

if your lockring is sloppy-- Lock tight it?-- or should your lockring since you use it as a brake
be high quality- proper thread and tightened by the proper tool-- which Park makes the best---I ride a flip-flop ss at the moment-- but by cog is Dura-ace and so is my lock-ring--- nothing moves....
I would tell you to avoid locktight.... but wait for more opinions....

To tighten the lockring, you should use a lockring tool.

If the lockring is not right (loose, not reverse threaded, stripped, etc) then you should fix it so you have a snug fitting lockring that is reverse thread. If you have such a lockring you will not need anything except the lockring tool to tighten the lockring.

Although you can screw on a bottom bracket lockring onto a freewheel hub, it is not reverse thread and will unscrew if you try and slow or stop.

If you are on the street, have no brakes, and you lose your connection to the rear wheel (i.e. your cog unscrews, your chain breaks, your right crankarm fails, etc), you will have a hard time stopping. One of my (reckless but also creative in survival skills) teammates had this happen to him and he had to jam his hand between the front tire and fork (behind the fork). He burned through his glove, part of his hand, but he slowed enough to turn and fall over somewhere other than a 4 lane road full of traffic. Don't ask me wtf he was doing riding a true track bike in the middle of traffic but he was.

cdr

I use grease on both the cog and lockring threads, tighten the cog with a chainwhip, and then tighten the lockring with a lockring wrench.

id assume you'd use locktight to prevent any movement on the threads. Actually it seems like common practice from what I've seen. I could be mistaken though.

This is common practice among bike shops. Since the owners are of uncertain mechanical expertise.

People who know or have the tools to tighten lockring/cogs will only put grease on them. And anyone who actually takes care of their stuff for that matter.

Yep, all of the above, but to add....

I use a high pressure grease on the threads of both the cog and the lockring. I then chain whip the cog on, and tighten the lockring to the recomended torque value (typically 30 foot pounds) with the proper tool.

The tricks- Get a steel lockring right off the bat, if you are running Formula hubs etc. with the anodized aluminum lockring I suggest you keep it in your spares bin. Steel lockring is critical, especially for street use.

Then mash your heart out for a few minutes, then go back and re-torque the lockring. Periodically check your lockring as basic maintainance.

It's important to get your cog on nice and tight before you put the lockring on (otherwise, if your cog starts backing off, you can strip the lockring threads, which isn't a good thing). What Erzulis Boat mentioned is one technique. What I (and a lot of fixed riders) do is a technique called "rota-fixing", which basically involves immobilizing the chain (and, thus, the cog) and rotating the wheel with your hands. Since wheels are large, this gives you a _lot_ of leverage to tighten the cog. There is a good explanation, with pictures, here: https://204.73.203.34/fisso/eng/schpignone.htm (Note that I don't recommend riding without a lockring on the street)

Note that this technique causes a lot of pressure to be applied to your bottom bracket shell. At the minimum, you should probably protect the frame contact area with a rag folded over a couple times.

you can avoid all this and do what Sheldon and and I do and NOT use a lockring