I also have the very same problem, started when i put a new chain on, the noise is like a grinding creaking sound and occurs when putting a bit of power through the right hand crank at the 2 o'clock position, removed the cranks checked the chainrings, removed the BB, done the seatpost and the pedals and still can't find it, the last time i had this noise i had a cracked frame but i can see no (visible) crack this time.