Schwinn Men's bicycle that uses Shimano Coasting Automatic Shifting system. The Coasting system uses a 3-speed internal hub. The shifting is done automatically by the “Automatic Unit.” The electricity to operate the Automatic Unit comes from the dynamo (generating) front hub. From a speed of zero, the bike begins in the lowest gear (first gear). As the bike picks up speed, the dynamo hub produces more electricity and a winder mechanism in the Automatic Unit pulls a shift cable chaning to 2nd gear. With more speed comes more electrical power, and the winder pulls the shift cable more and the bike shifts to the highest gear, third gear. As the rider slows, the electrical current drops and the bike again shifts back to second and then to first gear. 22" frame.