I've had this before, and there are a variety of causes. After you check teetime's advice.....

1-check your pedal cleats, if you run clipless. if not, check the toe clips.
2-rem/reset the crank arms, but the tick in that case is often associated with a slight jerk of the crank arm, too.
3-usually, it's not the chain, but check it anyway, for a link coming apart.
4-usually, it's not the RD pulley's, but check them anyway.
5-check the seatpost binder bolt, and the saddle cradle. It may not be TDC, but where your butt is at TDC....
6-it's usually not the pedal bearing, but check it anyway.
7-it could be the BB, but not likely. with the cranks off, a good time to double-check that by rem/resetting.

Try it in different gears. If chainline makes a difference, it's probably in the bb/crankset area.