Fixed Cog Meaning in Cycling

A fixed cog is a rear gear that is threaded directly onto the hub of a bicycle wheel. Unlike a standard gear, it does not have a freewheel mechanism that allows you to coast. This means that as long as the rear wheel is turning, the pedals must turn too. You cannot stop your legs while the bike is in motion without stopping the bike itself. This creates a direct connection between the rider and the road that many find rewarding. It is the standard setup for all track racing bikes used in velodromes. Because there is no clicking mechanism, it is incredibly quiet and mechanically efficient. Most people use a lockring to ensure the cog does not unscrew when they try to slow down. For example, a track cyclist uses a fixed cog to control their speed entirely with their leg muscles. They push back against the pedals to slow down before a turn since they have no brakes. It is a simple and pure way to ride.