World champion Mark Cavendish crashed at a one-day race in Belgium on Wednesday as a result of a bottle thrown by another rider.
Team Sky's Cavendish reiterated his belief riders should be licenced to compete after the incident at the Dwars door Vlaanderen race, which was won by Holland's Niki Terpstra (Omega Pharma-QuickStep).
Cavendish said on his Twitter account: "Said it before: EVERYONE involved in a bike race should take a written & practical test to get licence. Bottle that crashed me was (from Russian team) Katusha."
Cavendish was racing for the first time since not finishing the Milan-San Remo Classic last weekend and will bid for glory in the Gent-Wevelgem one-day race in Belgium on Sunday.
Team Sky sports director Steven de Jongh added on www.teamsky.com: "Unfortunately Cav had a crash but that can happen in any race. His shoulder is hurting but that's from the impact itself and he looks to be okay.
"We'll make absolutely sure that's still the case tomorrow morning."
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