 18 km ( 11 mi ) from the end of the stage , Tom Boonen clashed wheels while riding at the back of the peloton . He fell on his shoulder and , after receiving medical attention , abandoned the race with a suspected broken collarbone . That evening , it was announced that , though his collarbone was not broken , he had suffered a dislocation in his shoulder and would miss the Spring Classics season , including his principal targets at Paris – Roubaix and the Tour of Flanders . 
