Bicycles with hub gears or a singlespeed drive have only one sprocket on the rear wheel. Since the chain does not shift between gears, the teeth are generally longer, higher and the tooth profile is wider overall. At this point, a distinction is made between two different designs. There are two different types of singlespeed sprockets. One where the freewheel and sprocket are one piece that screws on to a hub. The second type consists of a sprocket and spacers, these will fit onto the existing freehub body of your wheel.