BSA was once the largest - and most successful - motorcycle company in the world. Many of the most famous 'Beezas' were powered by twin-cylinder engines, in both vee and parallel configurations. During the interwar years BSA built a series of side-valve and overhead valve v-twins in 500, 750 and 1000cc. After the Second World War, BSA built a family of vertical twins in 500cc A7 and 650cc A10 guises. Their names bring back fond memories: Star Twin, Shooting star, Golden Flash, Road Rocket, Super Rocket and the magnificent Rocket Gold Star. This is the very first book to deal exclusively with both the interwar v-twins and the postwar A7/10 series.