I've been plagued by a creaking apparently from the bottom bracket for a while now. I've changed the bottom bracket (it needed doing anyway and I wanted to get away from the SRAM/Truvativ setup) but the creaking persisted. Having had a dig around on here and speaking to Orange I've finally solved it by cleaning (and greasing the relevant parts) of the rear quick-release and dropouts. In more detail:
– Clean muck from the faces of the dropouts
– Check / tighten the hanger bolts
– Clean muck from the knurled ends of the hub and skewer ends that bind with the dropouts
– Grease the face of the cam on the QR
Tada. Sorry to everyone I've annoyed the crap out of in the last few months.
Other possible causes of creaking
– Damaged/dry main pivot bearings
– Crank bolts
– Saddle/rails (easy to diagnose – stand up)
– Bottom bracket damage/play