I'll be doing this on the singlespeed (since as usual, I'm nowhere near getting the tourer back together). I really need to find me a new chainring and chain, since the current one sounds a bit 'orrible,
Have you put a new sprocket on, by any chance?
No, it's just wear, I've only done about 4000 miles on this arrangement, but I haven't done much other than poor more oil onto the chain every so often. The combination is clearly worn, the chain lifts away from the chainring, and under pedalling it can shift around a bit, making an audible click, which I can also feel through my feet.
I'll probably change the lot, I have a spare sprocket that I've wanted to put on for a while, the chainring is knackered, and it's not worth trying to reuse the chain (not that it would work very well anyway).
If this was a geared bike, the chain would probably be happily jumping around and generally making cycling it lethal, at least with the singlespeed it's just a bit noisy!