My bike started creaking recently on rides. It also creaks when it's standing still, with me sliding front to back to front on the saddle with my shoulder leaning on a wall. Guessing that the single bolt saddle rail clamp needed tightening, I torqued it up to 15 Nm, but the creaking is still there. The carbon seatpost is branded Colnago. I'd appreciate advice.

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Saura mon coeur que mon cul poise.

adapted from Rabelais

Use carbon paste on the contact points of your saddle rails to your seatpost and on the seatpost into your frame. I had several creaks this took care of them all.

The rails are metal, Fizik Kium. Will carbon paste help, in this case?

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Saura mon coeur que mon cul poise.

adapted from Rabelais

carbon paste is probably unnecessary on Kium rails. Try grease first or WD40 even.
It could be coming from where the rails insert into the saddle.

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2012 Scott Foil Premium

I use a saddle that has metal rails, trust me it will work.

i'm sure it works, just might be overkill.

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2012 Scott Foil Premium

Thoroughly cleaning the entire seatpost head assembly would be prudent. I would stay away from any grease or paste there, unless the problem returns (after being solved for a period of time).
Remove the post, remove the seatpost clamp. Clean it all, especially the split in the seat tube and deep into the tube. Put a smear of grease between the clamp and frame (regardless of material). DO NOT use assembly paste there. DO use assembly paste between the frame and post, but only apply it to the post at about the clamping area to 1inch down.
Creaks can come from anywhere. Sometimes the post is allowed to rock fore/aft in the frame due to insufficient clamping force. Depending on clamp orientation, friction between the clamp and frame can hinder tightening. Other times, the post and frame fit is a little loose, and even when it's clamped well, the lower part of the post will rub the inside walls of the seat tube when the frame flexes. Assembly paste, while great for clamping, can lead to creaks when not being fully clamped, like down low in the seat tube.

I used paste, following thisatest' s recommendations as closely as I could. It worked. The creak is gone. Thanks to all responders.

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Saura mon coeur que mon cul poise.

adapted from Rabelais