Tick tick tick
 

For a bit over a week now, my bicycle has made a distinct "tick" sound almost everytime the crank turns - at the same rotation each time (when my right pedal is at about 5 o'clock). The tick occurs when I pedal with both legs - peddling with either the right or the left leg exclusively I don't get the sound, so whatever is causing the noise must be related to alternating stresses on the crank machinery. Same sound clipped in or with platform pedals. I can't reproduce the sound when I'm not actually bicycling.
Any ideas what might be causing the sound, and what to do about it?

Would look at the front derailler cable, is the end of this contacting the crank at the 5 o'clock point? could be the BB starting to go or many other this. Have you changed anything recently on the bike? too many other options, look at the sticky at the top of the front page for more suggestions.

Just what I was going to say. Brake/Derailleur cable hitting foot and snapping back against frame?

That would be too easy :-) . No, it's not a cable. I'll go check the sticky thread, but remain open to other suggestions.

It could be your seat or seatpost. Does it make the noise if I stand while pedaling?

i had a tic from my crank hitting my waterbottle cage. took longer to find than you would think, even if you did know me.

...huey

Did a chainring bolt fall out maybe? If not, then (if you have the tools) just take your cranks off, your bottom bracket out, clean it all, grease, and reassemble. Almost guaranteed to get rid of it (the shotgun approach).

If you can't locate the source of the problem due to silly things like derailler or cable contact, I recommend starting as far out as you can, and moving in. If it still creaks when you're out of the saddle (assume it does), then you can skip the seatpost/saddle, and move down to the bottom bracket area. I start with pedals, move to chainring bolts, then to bottom bracket (clean and regrease the bottom bracket shell and square taper flats.

Thanks for the advice. I guess I'll have to start reading up on bottom bracket maintenance.

Before you start tearing the BB apart, can you have someone else riding next to you verify the sound actually comes from that area? From top of bike, it's easy to locate the source in terms of front/rear, but more difficult in up/down plane. Years ago one member reported clicking sound but only when pedalling off the saddle. After futile repair attempts in the crank arm/pedal/BB area it turned out to be part of his clothing clicking against the top tube.

I had pretty much the same symptoms that gradually got worse, and it turned out to be a bit of dirt in the plastic cup on the cartridge bottom bracket. I also had a similar symptom on my road bike quite a while ago, and it turned out to be a CO2 cartridge in my seat bag. If it's not making any more ominous sounds than a tick, and you don't start feeling it in your pedals, it's fine to take the time to locate it before you start taking things apart. Or, as someone suggested above, the shotgun approach can work.

+1 Same thing, easy fix.