A fixed-gear bicycle is one that has only one gear ratio and lacks a free wheel. An advantage of these bicycles is that you do not need to use the brakes for slowing down. All you need to do is to stop the pedals from spinning. This, in turn, slows down the back wheel and brings the bike to a stop.

The disadvantage is that you cannot coast on such a bicycle. You can either drive it by turning the pedals or slow it down by putting pressure on the pedals. You cannot allow the pedals to spin on their own because they may cause injury to your calf muscles or ankles.