Originally Posted by Kontact

CF composites are long fibers in a plastic matrix. But that process always involves a "lay up" because you can't "inject" fibers into a mold and expect them to orient correctly to greatly change the structural rigidity. Mainly what you get by adding short fibers to injected thermoplastics is increased shear strength rather than greatly increased stiffness. It will still act like nylon, just not break when pushed past its elastic modulus as easily.

The reason CF is strong is not because of the plastic, but the fibers. The plastic resin keeps the fibers oriented and provides some shock absorbency, but the plastic part is barely structural. The resin is more like hard candy than aluminum.


I think you could make a decent bike out of good fiber and fairly "weak" resin, but you'd have an awful hard time making a decent bike out of great plastic and poor fibers.