I have carbon rails on my infinity seat. First one broke just behind the clamp, and I assumed it was because I was sitting up a lot on the trainer last winter. Bought a new set, and followed the instructions to the T. (Don't remember ever seeing instructions the first time though). Second one lasted about a month of rides. I had to take a screen shot of the video, but this one broke both sides just in front of the clamp. Lucky for me it happened about only 6 local, in town miles from home, so I could ride gently home. New to this modern stuff, and I thought I needed carbon rails since the bike came with them. But this clamp cradles the rails from top and bottom, so either will work. Sticking with steel rails.
