I had this problem when I installed a stem that was slightly too small for the head tube. Lots of clicking and creaking. I remedied it 99% by shimming the stem with sheet aluminum, but it still can make a slight click if I stress the bars on a hill climb. What I neglected to do is grease the mating surfaces of the stem and expansion wedge; it's the probable source of the remaining noise. Some day I'll get around to it.