Totalkos,

I've had creaky handlebars on both my road bikes - from new on my Dawes and on my old winter bike, after installing new alloy bars & stem. The problem was where the bars and stem meet. When the bars flex the aluminium surfaces of bar and stem don't slide smoothly as the bar flexes but stick and slip past each other, resulting in a creak. A small amount of movement between these components cannot be avoided
I fixed this by removing the bar from the stem and applying a thin film of grease to the inside of the stem and around the bar. When everything is properly tightened up, there is no chance of the bars slipping/twisting out of position - I have ridden many trouble free (and quiet) miles. Please besure there is no damage to the bars or stem first though!

Hope this helps,

Ed