This is probably my main point of criticism with this frame (worse than the Mavic speed release). Single bolt saddle clamps are the absolute worst. I've added carbon paste for increased friction and tightened the bolt as much as I dare, and the problem is for now solved - until I hit a small pothole or something.
Ok thanks I'll try your strat, and report
about the mavic speed release, I bough one extra Real mavic speed release (with the torque lever thing) to get an extra one , and they are so much better than the normal one.
Its a bit sad that velobuild went for those speed release if they don't provide the "real" one, but I understand it's a money reason