Bicycles are very popular today in many countries. Many people use bicycles for exercise. But exercise is only one of the reasons why bicycle are popular. Another reason is money. Bicycles are not expensive to buy. They do not need gas to make them go. They also are easy and cheap to fix. In cities, many people like bicycles better than cars. With a bicycle, they never have to wait in traffic. They also do not have to find a place to park. And finally, bicycles do not cause any pollution!