In your textbook, you learned that efficiency is the ability to perform in the best possible way with little wasted energy. The bicycle is an invention that makes travel more efficient. Using a bike, you expend less energy in covering a distance 
than by walking or running. Bicycles with multiple gears help you to be more efficient when riding a bike. They allow you to use a lower gear when climbing hills and a higher gear when riding downhill or on the level.
Click here to learn how some teens created an even more efficient bike.
