Places I’ve found creeks on my bike included but are not limited to:
Saddle rails on seat post
Saddle bolts holding saddle together (brooks)
Saddle springs ( brooks flyer)
Seat post
Chain ring bolts not tight
Chain hitting chain guide occasionally
Bottom bracket
Bottom bracket threads needed PTFE tape
Chain not clean enough
Chain had the chain lube washed off
Pedal threads not greased
Smashed bearing with all the ball bearings ratting about in the bearing race. Almost the death of a frame.
Snapped seat tube. It was the death of thhe frame. At 10 years old off a decent jump at fort William dh I thought it was fair wear and tear.
Fork top cap not correctly tightened.
Bulging tire juuuuuust brushing the fork under hard cornering
Broken rack
Broken p-clip holding rack on
Good luck, by carbon road bike with a press fit BB and internal hoses started creaking today.
I hate mystery creaks