Not every fixed gear rider is an insane skidder. I ride a fixed gear with front and rear brakes and I do skid (more lately as I am getting ready to put a cheep track wheelset on with nice araya aero rims that I don't want to brake too much on because they don't have a flat braking surface, but anyway...). I have been running a 16t 3/32 dura-ac cog for over 2 years on my fixed gear screwed on with grease! at first it came off a few times when I tried to skid to I road it a lot and used the brakes always.... I only skid in the rain for fun where there is little chance of spinning the cog off... now there seems to be nothing I can do to get it off, no matter how much I skid and how much weight I thrown on it while skidding.... but as I said if you run brakes it's not much of a problems... often when it broke free I'd sit down, brake an pedal the cog back on before it came off and kept going. I didn't have enough room for a lockring BTW.