7x9 saddle rails in sideload seatpost problem

Bike: Factor One V2
Saddle: (old beloved) Selle Italia SP-01 Superflow Carbonio
Seatpost on bike is similar to BlackInc.

When I install saddle it sways back and forth by 2 degree. I found that 7x9 mm saddle rails is too thin to fit to 7x9 mm (!) saddle clamp. The rails width is OK. But the height is not enough. Clamp bolt tightened with manufacturers torque: 12 Nm.

You can see about 0.3 mm gap between rail and clamp ear.

I tried following:

  • Tapes: insulation, duct, galfer, friction, cloth. All of them are too pliable and squeezed off from clamp after one hour.
  • FinishLine Carbon paste. Clamp started to creak. Still rocking about 1 degree.
  • Motorrex Carbon paste (without particles). Silent but sways about 1 degree.
  • I still not tried “beer can shim” because I have no idea is this safe or not.
  • Contacted to Factor. “Do you have 7x9 saddle and use 7x9 clamp - Yes - We’ll send you replacement”. I got absolutely same clamp with same problem.

Has anyone had the same problem? And hopefully solution? Any ideas will be warmly welcomed.

The photo looks like you are point loading the rails. Maybe a new seatpost, to match the saddle, would be easier. Thomson make an after market clamp designed for carbon rails. Bontrager and Hope do as well. It supports the rails for the full length. Otherwise you could end up destroying your saddle rails.

Unfortunately it’s not possible. See bike model.

The factor seatpost rail clamp looks like it has a circular aperture similar to the Bontrager unit. Maybe you could just buy the Bontrager clamp?