I put a new Selle Italia Flite saddle on a Bontrager seat post and had a squeak. Thought it was the saddle since I had an older Flite saddle on it and it was quiet. It turns out that the leather edges of the saddle where there are tucked under rub the top rail cradle of the seat post (my saddle is pushed all the way back). Anyhoo, took a while to find it, but when I did a little non petroleum lube on the cradle stopped the squeak. Be careful though, petroleum lubes can dissolve the glue that holds the leather down. Just my experience.