The cyclists were travelling in a small group in Spain's Burgos province when the bird flew into the pack.
"The vulture was flying very low along the centre of the road, and was coming straight at those at the head of the group," the cyclists told El Correo newspaper.
"Some of the group smacked into the wings, others against the bird's body and other into the cyclists behind them," explained Javier Sagarribay.
One of the group, Mario Sánchez, was rushed to hospital with seven broken ribs, a fractured shoulder blade and collar bone and a punctured lung.
He is now out of danger but remains in hospital in the town of Miranda de Ebro.
The collision took place on a blind turn with very poor visibility, Sagarribay explained to El Correo.
The bird was "trying to take flight and it and we couldn't see it because the curve was so tight," the cyclist said.
"We weren't going that fast, but there was no time to hit the brakes."