When replaced the stock saddle on my Cannondale Synapse, I started having a lot of creaking. I tried everything I could think of. Finally, a couple of weeks ago I was doing a thorough cleaning of the bike and pulled the seat post, clamp and seat off the rails. I cleaned everything really well and relubed the tube with carbon paste and applied Superlube to the outside area where the clamp is located, clamp bolt and nut and the seat rails and tightened to torque spec. My creaks have disappeared. I like a quiet bike and this worked for me. Good luck.