Singlespeed & Fixed Gear - Creaking noise?

I've recently noticed a kind of creaking noise coming from, I think, the front end of my bicycle, though I'm not sure because it sometimes sounds like it is coming from the cranks. Maybe it's the wheels? What could be causing the creaking? I think all the parts are greased adequately. The frame is 4130 chromoly and I recently switched from drops to nitto RB-021 bullhorns.

Advice is appreciated.

your saddle might not be firmly tightened in the seat post. Loose chain ring bolts will do cause a creak as well. Lose bottom bracket maybe.

I havce a creak going on at the moment. I first assume chainring bolts. Those were fine. Then I assume cranks/bb. Cranks were fine and BB seems to be seized in, so those are fine. My saddle is just squeaky anyways so I ignore that. It turns out its the wheels. I have ridden then enough that the spokes have worked themselves into eachother, and as tension has been lost they ping/creak when I put load on the spokes (starting/stopping). bars, stems, racks and fenders can also make funny noises...

i'd check chainring bolts first as well.

If the noise goes away when you stand up, grease your saddle rails.

I think I'll take it into the shop to have all those things looked at. I don't think it's the chainring bolts. The seat is a definite possibility since I'm constantly adjusting it, trying to find the *right* position. Also, the wheels are newly built and now have a about 100 miles on them so I should probably take them back to the shop and have the spokes re-tensioned since they've had time to settle.

Thanks for the suggestions, gentlemen.

I thought this was going to be about knees.

I thought this was going to be about knees.
I think the only time my knees don't creak is when I'm on one of my bikes!

Creaks can be maddening and hard to track down. The only advice I have is to be systematic and start with the easy ones. Work your way up to bottom bracket and spoke tension.

loosen your handlebars and move them just a hair. Try this first.
Could be a loose spoke/spoke tension.
Seat bolts could be loose.
Tighten any and all screws/bolts in the bottom bracket area.
If its bottom bracket, take out and regrease the threads.

also check to see if the creak occurs with your cadence.