Thierry Gouvenou, race director at Paris-Roubaix, believes he has identified a fatal error. He says the rapid pace of descents is one reason for the increasing number of falls in cycling.

On Thursday, top stars Jonas Vingegaard and Remco Evenepoel, among others, suffered serious bone fractures in a mass fall during the Tour of the Basque Country. For the one-day race from Paris to Roubaix on Sunday, the planners have installed a chicane to reduce the speed.