From Wikipedia: Bobber

...a bobber is a custom motorcycle that usually has had the front fender removed, the rear fender "bobbed" or made smaller, and all superfluous parts removed to make it lighter. The bobber was the earliest simple and stripped down custom motorcycle hand-built by individuals with mechanical skills and often part of the early biker clubs scene before there were any such thing as choppers. It is a style of custom motorcycle which took shape in the 1940s and 50s, generally thought to have been started by returning WW II American servicemen working on ex-military motorcycles and inspired by lighter European motorcycles they had seen and ridden...