- from Bicycles
A bicycle is an easy-to-understand machine. Most modern ones require only about 1,500 parts!
In the last hundred years or so, bikes have been given some important tweaks, such as gears and hand-operated brakes. But the bicycle’s basic design has remained unchanged since the 1880s. Every bike relies on a foot-powered cog-and-chain system that powers the back wheel (another word for rear cog is “sprocket”). That makes bicycles the most efficient form of human-powered transportation – more so than walking and running or riding scooters and skateboards.