Abstract
The study considers the energy requirements for bicycling-introducing ergonomics and the food-filled, air-breathing, air-cooled "human engine". It continues by reviewing the natural forces opposing motion and applied braking forces, steering and stability, and construction materials. Design criteria and considerations are given within the limits imposed by human capacities and the irreducible forces of wind and road resistance. Past, present and possible future bikes are described and illustrated, plus some unusual applications of "people-power" to other modes of transport.