This morning during my morning commute I had an unintended lesson in fixie skidding: I dropped the chain, it got stuck between the cog and the hub and locked the wheel. I'm not sure where that skill came from, but I managed to come to a controlled stop without falling, crashing into the curb, or swerving into traffic. Scary, I must admit.
I was only a few blocks from work, so after a good deal of not-so-gentle pulling I managed to dislodge the chain, get it on the chainring and cog and get going. I did notice during the short remainder of the trip that if I applied back pressure on the pedals, the cog was no longer being held in place by the lockring. Not that I understand how that could have happened, but other than that and the terrible skid mark on the tire, nothing else felt wrong.
Once I get home I will get a new tire on (kids, put brakes on your fixies, if only for financial reasons!), tighten the cog and lockring, check them for damage, measure the chain to see if it needs replacement, and make sure it sits a little more taut.
Am I missing anything? Not sure if I should be looking at anything on the hub, spokes or elsewhere...
Update I spent some time with my back wheel today. The spokes are all dented and scratched, but the wheel is holding up well. I took the lockring and cog off, and they both looked fine, same with the threads. After cleaning them up and putting some grease on the threads, I put the cog back in and tightened it with no problems, but when I was tightening the lockring it disintegrated: it obviously cracked during the chain jam, which allowed it to move out without stripping the threads. I am riding on the flop side of the wheel now, which has made for an interesting discovery of forgotten feelings. I had been thinking of taking a tooth off my back cog for some time, so I'll just go ahead an order the whole pack: cog, lockring and chain.