The 30-year-old Frenchman, who earlier this month finished 14th at both the Tour of Flanders and Paris-Roubaix, said via Facebook that he was the victim of an assault with a blade and a baseball bat while he was out riding with two friends.
"Result: a fractured nose, a rib in a dirty state and bruises all over the body," he wrote. "But beyond physical wounds, I am especially shocked.
"I'm not angry, I'm just sad to find that this beautiful sport that I like, I do not want my kids to practice ... too dangerous.
"You leave for training in the morning, but you never know if you're going home."