Quote:
Originally Posted by freebeard
And the lack of high-speed production is down to the vacuum-bagged autoclaving. It's purpose is to minimize the amount of binder — epoxy or whatever — in ratio to the fibers, to maximize strength (toughness, whatever) for weight.
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Same is true for fiberglass and resin--too much resin actually weakens the final product at the same time as it's heavier than it needs to be. All those "crap" homemade carbon pieces probably suffered from this.
To my knowledge, the autoclave process does not harden the fibers themselves. I've examined smashed bicycle frames, for instance, where the fibers tore, and they're still quite flexible.
With carbon fiber, you have to look at where the force is applied and in what direction. Depending how you orient and lay the sheets, the finished product will be stronger in one direction than another. Those bicycle forks, for instance, were not designed to resist a concentrated force on the side of one leg; they were designed to resist vertical forces from the mass of the rider transferred to the wheel and then road. (Same theory as a spoked bicycle wheel--they can be quite strong vertically, but you can easily pull a tensioned spoke from the side and rip it out of the hub or rim). Gram for gram, carbon fiber bikes are much stronger than steel or aluminum, and thus can be made lighter (and made into complex shapes more easily). They're also more comfortable than aluminum, as carbon fiber absorbs more road vibration.