Weird clicking noise while pedaling?

I have an 18 speed road bike and whenever I pedal, I hear a clicking noise every time I rotate past the top of the pedal cycle. It sounds exactly like what you hear if a gear doesn't shift properly, only that's not the problem. This happens on every speed when I'm riding, however it doesn't make this sound if I were to just turn the bike over and rotate the pedals with no weight or wheel movement on it. What do you think could be causing it?

The pedal. Swap pedals and try riding it.

+1. Just had the same clicking sound last month on my bike coming from the RH pedal. It did sound like a bad chain or cog, but since it was always in the same place on the pedal stroke and occurred in every gear, knew it wasn't one of those. I've had "creaking" from the crankarm/spindle joints before and it didn't sound like that at all. Plus, the noise actually disappeared when standing under heavy loads.

As I posted, the pedal were tight, but the crankarm had a very small amount of (aluminum) corrosion under the SS pedal spindle flange. Removing the pedal, cleaning the "seat", grease and retorque did the trick. Based on my experience, seems every joint on the bike where a steel fastener or part meets an aluminum component is prone to making noise eventually.

thanks!

I could be the lower bracket. This happened to both my road bike and MTB after 3000 to 4000 km.

And if it's none of these, make sure the crank isn't thwacking the end of the front derailleur cable.

I'm with old bob. Right side; click at the top of the stroke; annoying.
Check the front d cable then check the bb making sure it is not vibrating/rattling.

Thanks for this helpful advice.