Pull out the pivot bolts and make sure they are clean. One of mine got gunked up after some rain and about drove me insane.
The first time I replaced my BB before I "found" my loose skewer. The second time it only took me 20 minutes of riding/testing to remember to check it, next time it will be the first thing I check.noodletips said:Tighten the rear wheel skewer a little and see if it affects the noise. Maybe not, but this has removed creaking under power application for me. It takes but a moment...