The Trek STP 400 was Treks go at a carbon soft tail mountain bike. The idea of a soft tail is that rear of the bike has a shock but no hinging point. It uses the flex of the frame material to actuate the shock. Trek used the flex of carbon fiber chain stays to actuate their suspension. While I don't know the exact specs, one would have to assume this design is going to see more cycles and more flex than a typical road bike fork.