The Wrights brothers made their bicycles by hand. They made approximately 300 bicycles from 1896 to 1900. Building bicycles helped them build an airplane. To make the bicycle wheels go around they used a chain and sprocket system. On the airplane they used a chain and sprocket to turn the propellers. They built strong, lightweight bicycle frames. This helped them build a strong, lightweight airplane. Their bicycles and their airplanes had a lot in common.