Difficult to diagnose, I know.
Basically, I bought a single speed Schwinn a few months ago, and after riding it for a couple of weeks it started clicking in the back wheel somewhere.
I've taken it in for a tune-up, mentioned to them there was a clicking sound, but they didn't notice anything (or didn't pay attention), and it still clicks.
It doesn't click, however, if you just pedal it with your hands, but seems to have something to do with putting your weight on it when you're actually riding.
Should I just take it in again? Or is there something cheaper I could look at?