The stolen German army bike Steve McQueen is riding is actually a Triumph. Perhaps they captured it at Dunkirk?
He rode a Triumph with extra padding on the seat because he had piles and found it painful going cross country. Watch how many times he's riding the bike half-standing.Apparently McQueen is being chased by himself, as he also doubled as one of his German pursuers,. As a motorcycle enthusiast he was keen to do his own stunts, and any other stunts he could wangle his way into