Unlike steel or aluminum, carbon fiber does not bend in crashes. Rather the bikes and wheels frequently shatter, often hurling riders to the road and, many fear, increasing the severity of injuries.
And check out this section, about how light these bikes can get:“Anyone in a team who’s being honest with you will tell you how frequently their bikes are breaking; everybody knows,” said Mark Greve, a physician and assistant professor of sports medicine at Brown University who studied injuries to 3,500 competitive cyclists. “Few people in the public appreciate how many bikes a pro team will go through in a season, because they break for one reason or another. The bikes, they completely explode.”
You'll probably want to read the whole article, which has details about how the new bikes are constructed, and even about how the carbon fibers themselves are made. It's fascinating.The International Cycling Union, concerned about the potential danger of ever lighter carbon bikes, imposed a minimum weight of 6.8 kilograms (about 15 pounds) in 2000 for bikes used in high-level races like the Tour. But that applies to the whole bicycle, including the wheels, leaving bicycle makers to continue a marketing battle to produce ever lighter frames. Professional teams simply add weight, sometimes pieces of chain, to a bike that doesn’t meet the minimum.Before the Tour started, Trek launched the latest salvo in that war: the Émonda SLR 10, a frame that weighs 690 grams (about 24 ounces), making it, the company says, the world’s lightest bike. It sells as a complete bike for $15,750.