The more you look at a bicycle, the more incredible it appears. The perfect human-powered form of transportation? We think so. Take the fact that you're using the same amount of calories as walking, but getting around three times as fast - the equivalent of a car doing 1,037 km per litre. At a time of escalating obesity due to lack of exercise in Western society, bicycles offer steady, low-intensity exercise and we're enjoying the fresh air every time we pop to the shops.