My Megatrail spec'd Shred Dogg has been creaking for a few weeks. I've gone through the pedals/cranks/BB, replaced the lower headset assembly, used wicking loctite on the CSU/stanchion interfaces and checked/re-torqued all of the pivots.
You can hear it throughout the video below... any ideas?
Does it creak standing and seated?
Does it creak in all gears?
Things that you may have not checked:
Pedals, chainring, cassette, seat post binder, seat clamping mechanism, seat.
Last case scenario, which was the source of my creak:
Off the bike, standing to the side, load the crank arms one at a time. Does it creak when you push on one side more than the other?
Check the rear most pivots next to the axle. The pivot bolt is threaded into the chainstay, it can strip, that would make it creak.