The rocker subculture came about due to factors such as the end of Post-World War II rationing in the UK and a general rise in prosperity for working class youths, the recent availability of credit and financing for young people, the influence of American popular music and film, the construction of race track-like new arterial ring roads around British cities, and the development of transport cafes that became their haunts.
These factors coincided with a peak in British motorcycle engineering. It wasn't until the 1960s that they became known as rockers and they were immersed in rockabilly music and fashions and began to be known as much for their devotion to rock and roll music as they were for their motorcycles.wiki
