how long does a cog usually last in terms of the teeth wearing down?
I want to know because I have a 48x17 gear ratio with a surly cog and I wanted to loctite the cog onto the hub and didn't want to have to buy new rims that soon. Thanks.

that's the dumbest thing I've ever heard of. Why not just get a lockring and ditch the loctite?

Just tighten it down correctly and you won't have to destroy your hub.

I forgot to mention i stripped my lockring threads and am loctiting the cog and lockring. Can someone just give me a straight answer?

How many miles do you ride/week?
Do you maintain/clean/replace your chain?

Ah. Well then, I'd say rotafix it on the freewheel side (assuming there is one that way you can get a bottom bracket lockring on there too), loctite, and pray. Just make sure to keep your chain clean and lubed and it should be fine for a long time to come.

I have seen suicide hubs on the web with BB lockrings. I think it's a good idea as more threaded contact area the better. But you should put on two brakes, as I am sure you can rota-remove the cog even at the worst possible moment. ... Actually if you go that far, slapping on a freewheel might be more satisfying choice.

Come to think of it that's a clever idea to get extra mileage off of stripped hubs avail at junk stores. Do people do that?

OP: is your hub one-sided only, or are there freewheel threads on the other side?

Replace your chain at the appropriate time, and you should be able to get many thousands of miles out of your cog. YMMV, depending on riding conditions. The dirtier things are, the faster it will wear.

If you run brakes, you could just rotafix the cog on using grease.
As long as you don't skid you won't spin the cog off.

abot 100 miles
yes i make sure my chain is in full working order

freewheel threads on other side. Is there something I can do?

True, but one of the reasons I ride fixed is to skid

Rotafix the cog onto the freewheel side, put a bottom bracket lockring (same thread direction as cog) on, tighten it. Ride around without using any backpressure. Retighten the lockring.

Use a brake for hard stops, periodically check that the cog and lockring are tight, and it should work fine for a long time. Skidding should be fine, but take it easy on the hard skip-skids.

1. Grease all threads
2. Install cog per usual via rotafix
3. Install BB lockring using an actual lockring tool
4. Go ride

EDIT: Zacked beat me to it. Gotta refresh these threads when I watch half a movie. ANYWAY, if you do it right it's totally reliable. I rode brakeless with a cog set up like this for about a year with zero problems. Thing is, DO IT RIGHT.