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So, over the course of several months, I notice that my saddle has been creeping backwards on the seat post.

Road bike. Fizik seat post (two screws, one manual, one hex head.) Ti rail saddle.

I tend to break seat rails. I think it is fatigue related. And I range between 200 and 200 lbs. ;) I've used steel rails. Carbon rails seem like a bad idea. The current saddle has ti rails. I put the saddle forward because the break in the rails happens at the back, and I want to minimize flex. This is my current theory to stop breaking rails.

Anyway, I tighten the bolt plenty. I don't know how much, but I think that increasing the clamping force is not going to help, and I will eventually strip the bolt/nut.

Seems like more friction between the rails and clamp is what is needed. I don't know the proper way to do that. Any suggestions?

Thanks, Mark

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    Make sure to hover over the saddle on bumpy terrain. You don’t want to be smashing your butt into the saddle. – MaplePanda May 9 at 17:40
  • Aside - perhaps its the seat-rail clamp? Have you always used the same seatpost/saddle clamp? – Criggie May 10 at 2:49
  • Too little torque on the clamp can cause the slippage because of too low a clamping force but may also cause the break of the rail from metal fatigue because the saddle rocks ever so slightly. – Carel May 10 at 11:55
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Carbon assembly paste increases friction and can be used for metals as well. Make sure to use a torque wrench and tighten to the torque printed on the seatpost clamp.

From the photos of the Fizik seatposts it almost looks like only the back screw is actually clamping the rails and only with 8Nm tightening torque? If nothing helps I’d get a seatpost with two side-by-side screws and ≥10Nm torque.

I put the saddle forward because the break in the rails happens at the back, and I want to minimize flex.

Don’t compromise seating position just to avoid breakage.

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