Okay. I'll be the oddball here. I'm primarily an XC and trail rider. I ride a full carbon frame. The mainframe is made of two ultrahigh-modulus thermoplastic carbon fibre half-shells each with several intermediate-modulus layers underneath that are bonded together to an internal high-modulus "backbone" structure. The design is a hybrid monocoque with internal structural reinforcement. The swingarm is made of high-modulus thermoplastic bladder molded CF. The fork legs also use the same construction process as the swingarm as does my seatpost and handlebars. Fork legs, swingarms, seatpost and handlebars were produced by Easton under license from K2. The main frame was constructed natively at K2.

The bike has survived multiple crashes... some of them pretty horrific. In one crash, I missed an outside line, got flung down the side of a hill and slid a hundred feet with my bike bouncing along after me. In another accident, I stupidly hit a jump bad and endo'ed with the bike flying over me and tumbling end over end. After every crash, I do a UV test with vasoline and a blacklight and I also keep a record of impedence test points that I measure across with an ohmmeter to detect any problems in the frame. There have been several similar stories of nasty crashes and incidents involving the K2 Oz and ProFlex 4x00C series of bikes. In almost all the cases, the bikes survived fine. One guy on the ProFlex Riders Group forums did discover a crack in his frame and successfully repaired it. It wasn't an easy task but the fact that the CF is thermoplastic vs thermoset makes it possible. Additionally, thermoplastics are generally much better at surviving impacts and have less notch sensitivity than thermosets. The biggest issue with thermoplastic construction is that it's much more difficult to bond to metal parts.