The bicycle has changed a lot from its beginnings in Germany as a pedal-free "dandy horse," which is basically just a plank of wood with two wheels (you move by running along like a Flintstones car). The animation shows the two-wheeled vehicle's design from the dandy horse as it gains pedals and gears, as the wheels change sizes (with a brief stop at the penny-farthing, the ultimate in absurd modes of transport), and finally to our modern road bike.
Found on http://www.fastcodesign.com/3028191/a-visual-history-of-the-bicycle