One day a few years back ( late 90s ) I was browsing in Gregg's Greenlake Cyclery. A sales rep was there from one of the larger bicycle manufacturers, touting his firm's new carbon fiber frames. To show just how strong the material was he had a sample frame tube which he whacked smartly against one of the metal bike stands in the shop. "See, there's hardly a mark on it, it's actually stronger than steel !" The sales guy collared me, stuck the tube in my hand and told me to try it myself, which I did. Of course, the tube completely shattered.