Bike noises are hard to diagnose. I have a ton of experience sorting out these noises on numerous road bikes. Recently on my new Cervelo S2 it sounded like a nasty drivetrain noise. It turned out to be several causes, not just one:

• New chain (old chain was borderline, almost worn out)

• Creaky seat post: cleaned it, regreased the bolt, re-prepped and re-inserted post

• Dirty rear hub (Williams 38c): LBS cleaned, repacked rear hub

Now the bike is silent.

Other suggestions:

• LUBE drivetrain. Critical.

• GREASE pedal threads, make sure noise is not in pedals

• CHECK quick release lever tightness: loose QR levers can creak like crazy, particularly on CF bikes.