When it comes to making a bike today to challenge at the Tour de France carbon fibre is the only material considered, its amazing strength and weight savings have sealed its dominance, however unlike steel or aluminium, carbon fibre doesn’t bend in crashes it shatters often throwing riders to the tarmac increasing the severity of injuries.
Mark Greve, a physician and assistant professor of sports medicine at Brown University who studied injuries to 3,500 competitive cyclists told the New York Times;
Anyone in a team who’s being honest with you will tell you how frequently their bikes are breaking; everybody knows. 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.
The code of silence adopted by the professional riders, mechanics and team officials within the Tour de France named Omertá has allegedly masked the issues of carbon fibre and wheel durability in favour of paid sponsorships and endorsements by the large manufacturers. And when they do speak they are asked not to be identified.
Riders are describing landing on the top, horizontal tube of the bikes during a crash and ending up on the road after their frame had splintered and collapsed. Minor crashes and spills that used to mean straightening the handlebars now often require a complete bike change. Mechanics say they sometimes return the shattered remains of frames to manufacturers in bags intended to hold a single bicycle wheel.
Michael Kaiser, the head of product development at Canyon, a German company that offers both carbon and aluminium bikes, and provides bikes to two teams at the Tour, told the New York Times that with carbon, careful manufacturing was as important as design.
To get exactly the right result is more demanding than with metals, as it requires a comparatively large degree of work by hand. Therefore the entire manufacturing process has to be incredibly precise with extensive quality controls in place to ensure there are no defects in the parts.
To that end, Canyon use CT scanners to discover hidden defects in the forks, a potentially lethal point of failure, and will soon do so on frames.
Doug Perovic, a professor of materials science and engineering at the University of Toronto, said that carbon fibre was a bit like a diamond: strong while not being particularly tough.
The Boeing 787 Dreamliner makes up for carbon’s lack of toughness by building up several layers of material. Bicycle makers go the other route and use its exceptional strength to make the bike’s structure as thin and thus as light as possible.
When a Carbon bike is stressed beyond its limits it fractures into many pieces while metals bend, the energy absorption is the bending. While steel and aluminium bikes generally telegraph an impending failure by displaying cracks, carbon fibre generally fails without warning.
For consumers who are not constantly banging their bikes around on team vehicles and who are unlikely to be involved in crashes, the risks in buying a carbon bike made by a reputable company should be minimal. Greve said many riders had told him that the performance gains from super-light frames reached the point of diminishing returns long ago, and he questions the wisdom of consumers’ buying what are, in effect, very costly throwaway items if they crash.
Source: NY Times