Bicycle
Bicycle, also called a bike, is a two-wheeled steerable machine that pedals by the rider's feet. On typical bicycle wheels are mounted in-line during a metal frame, with the front wheel held during a rotatable fork. The rider sits on a saddle and steers by leaning and turning handlebars that are attached to the fork. The feet turn pedals to attach cranks and a sequence wheel. Power is transmitted by a loop of chain connecting the chain wheel to a sprocket on the rear wheel. Riding is definitely mastered, and bikes are often ridden with little effort at 16–24 km (10–15 miles) per hour — about four to five times the pace of walking.