Bicycles

A bicycle, also called bike, pushbike or cycle, is a pedal-driven, human-powered, single-track vehicle, having 2 wheels attached to a frame, one behind the other. Bicycles were introduced in the 19th century and now number about one billion worldwide, twice as many as automobiles. They have been adapted for various uses as children's toys, adult fitness, courier services and bicycle racing. The more common types include utility bicycles, mountain bikes, racing/track/pursuit bicycles, touring bicycles, hybrid bicycles, cruiser bicycles, and BMX bikes. Less common are tandems, lowriders, tall bikes, fixed gear and folding bikes. Unicycles, tricycles and quadracycles are also listed in this category even though they are not strictly bicycles.