July 22, 1999 -- Medical science led Lance Armstrong in his fight against cancer. Now materials science is helping him take the lead in the Tour de France.
For the world's most famous biking contest, Armstrong isn't testing his mettle with metal. He and other members of the U.S. team, are using a simple, yet powerful frame made of carbon.
Carbon is one of the lightest elements, making it an ideal material to use in the construction of lightweight bikes. Armstrong's bike frame is made up of tubes created using carbon fibers. The result is a bike that requires less energy to move. "If the frame has less mass, you can accelerate the bike with smaller forces," explains University of Virginia physics professor Louis Bloomfield.
Not only is the bike light, it's stiff. Carbon atoms in the fiber forge extremely tight "covalent" bonds with one another in the fiber, comparable to the tight bonds in a diamond, another form of pure carbon. A metal bike frame bends more easily, twisting in relation to the wheels, which forces the rider to adjust the steering more often than with a stiff frame.
But stiffness is a disadvantage when a rider has to go over bumps. No problem, say the folks at Trek Bicycle Corporation in Wisconsin who make the Model 5500 OCLV bike being used by the team. The "direction" of the stiffness can be controlled. The bike is resistant to the twisting forces, but flexible up-and-down. To do this, some of the fibers in the bottom tube are twisted in a barber-pole type pattern parallel to the length of the tube. "The ability to tune stiffness to this degree is not available in conventional materials," says Trek's Wes Wilcox.
Think carbon bikes are something only for the racing elite? Not so. You may not be ready for the Tour de France, but the bike is commercially available here in the US.
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