the birmingham small arms company (bsa) was a british company that started making guns and bicycles in the 19th century. from 1910 the company started making motorcycles. at one time, it was the most popular maker of motorcycles in the world. over half a million of the company's most popular model, the bantam, were sold. the company went out of business in the 1970s. it has started again as a gun making company.