“There are a lot more dangers than 20 years ago,” said Pat McQuaid, the president of the cycling union, which is more commonly known by the initials of its name in French, U.C.I. “But you can’t compare a death in a cycling accident and an N.F.L. player going into a tackle and not coming up. In the Weylandt case, it was an accident out of the blue.”

Many riders, however, disagree.

“When I started racing, they told me that crashes are part of the contract,” said Marco Pinotti, a prominent Italian rider who broke his pelvis in another crash in this year’s Giro and was hospitalized for several weeks. “This is a dangerous sport, and it will always be a dangerous sport. But I think in the last few years, it looks like crashes have increased and become more severe because the speed is higher, the technology of the bikes has changed, and the level and size of the peloton is higher, much higher.”

Pinotti, who became a professional 12 years ago, is now recovered and made his comeback this month in Quebec and in Montreal, the only North American races that are part of the U.C.I. World Tour, which also includes the Tour and the Giro.

Craig Lewis, Pinotti’s teammate and another Giro crash victim, has been less fortunate. Speaking from his home in South Carolina, Lewis said that he had regained only 75 percent to 80 percent of his usual form and that he probably faces additional surgery on a leg he broke in the crash. He did, however, finish the U.S.A. Pro Cycling Challenge last month in Colorado.

Pinotti and Lewis were brought down by a common problem. In a bid to slow auto traffic, towns, cities and villages throughout Europe have narrowed roads near their entrances, added speed bumps and introduced islands and traffic circles. In the Giro, Pinotti and Lewis came around a corner on a descent and struck a small metal pole on an island in the middle of the road.