Bicycle handlebar a steep U-shape from the base, so that the rider's hands rest above waist-level. This style of bicycle handlebar became very popular in the 1960s after the introduction of wheelie bikes such as the Schwinn "Sting-Ray", Raleigh Chopper, and other highly stylized youth bicycles that imitated the appearance of drag-racing or chopper motorcycles of the day. Legislation in the United States introduced during the 1970s limited the maximum height of manufacturer-installed handlebars to 16 inches above the lowest seat setting; European Union safety regulations use a similar limit of 400mm. The apehanger style remained common in the US through the
Gazelle (bicycle company) collectors item. During this period, Gazelle was to use the Piet Pelle cartoon character throughout many advertising campaigns. This video from 1925 shows the Gazelle factory and production techniques. Developments include a collapsible delivery bicycle in 1930 and a tandem bicycle introduced in 1935. An electric bicycle was produced in 1937 together with Philips. In 1954 Gazelle became a public company and built its millionth bicycle. In 1959, Gazelle patented the first 3-Speed grip shift gear system. Gazelle was the first Dutch bicycle manufacturer to introduce the "Kwikstep" folding bicycle in 1964. The front-hub drum brake was developed in 1968