Help! Creaky Cranks!

It's probably water in the frame. It runs down the seat-tube, and then forms a small creek running between the BB and rear dropouts. The water molecules rub together between the BB threads and the shell, and the hydrogen in particular is known to give off a creaking sound. The word 'creak' actually comes from 'creek' - it was the Celts who first used the term to describe the noise when fishing for Salmon.

Hmm. I'm not entirely sure I believe you...