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
Mountain bike terrain bicycle", "all terrain bike", and the acronym "ATB" are used as synonyms for "mountain bike", but some authors consider them passé. The original mountain bikes were modified heavy cruiser bicycles used for freewheeling down mountain trails. The sport became popular in the 1970s in Northern California, USA, with riders using older, single-speed balloon tire bicycles to ride down rugged hillsides. These modified bikes were called "ballooners" in CA, "klunkers" in CO, and "dirt bombers" in OR. Joe Breeze, a bicycle frame builder, used this idea and developed what is considered the first mountain bike. It was not until the