Exploratorium
Exploratorium: Drives and Gears
Discover the basic structure of the bicycle chain drive system, and find out how it has developed over the years.
Exploratorium
Exploratorium: The Science of Cycling
Very informative site from The Exploratorium about the science of bicycling. You can learn about the development of the wheel, how gears work on a bike, even how brakes were developed. Perfect site for research on bikes.