Originally Posted by wagathon
...Anyone who has ever seen an athlete running down the track and planting his CF pole for the purpose of hurtling over a bar more than 17' above the ground knows that this material can be constructed to serve as a bike frame...
Hi again, wag!
You're completely correct - carbon fiber CAN be constructed to serve as just about anything. The PURPOSE of carbon fiber, insofar as it applies to bicycles, though, is to reduce weight. That being the case, manufacturers routinely cut safety margins as much as they can to achieve the low weight that will sell their bicycles.
The side effect of cutting safety margins is that at least some of the carbon fiber frames and parts on the market are unsuitable (or, at the very least, unwise) for even normal-weight riders.
What is a "normal weight rider?" Therein lies the rub... Using U.S. anthropometrics, I'd guess that the normal young male is closer to 200# than 150#. As age increases, so does mean (average) weight.
Since bike racers are typically 150# or less, I submit that the average "racing" frame (or other carbon-fiber bike part) is being used at or beyond its design and, sometimes, close to its safety limit by even "average" riders.
The fact that most carbon fiber parts don't fail indicates that there is still some safety margin in carbon-fiber construction. I won't use carbon fiber parts, though - they just aren't designed for me.