A pedal for bicycles comprising: a pedal pin extending along a longitudinal reference axis and having a first axial end structured to be coupled to a pedal crank of a bicycle, a pedal body coupled in a freely rotatable manner on said pedal pin thus being able to rotate around said reference axis, at least one internal chamber is made in said pedal pin, having an internal surface extending in the pedal pin along said reference axis coaxial to the same, an electronic measurement system which is designed to determine the mechanical force/power exerted by the cyclist on said pedal during the pedalling and comprises: deformation sensors which are coupled to said pedal pin and are configured in order to provide electrical measurement signals indicative of the mechanical deformation of said pedal pin, electronic means which are electrically connected to said deformation sensors and are configured so as to determine, based on said electrical measurement signals, the mechanical deformation of said pedal pin caused during the pedalling by said mechanical force exerted by the cyclist on the pedal pin through the pedal body, an electric power-supply device which is designed to provide the electrical power for the operation of the electronic measurement system, said pedal being characterised in that: said electric power-supply device comprises an electric generator which is arranged inside said at least one internal chamber of said pedal pin, and is structured to convert the rotational movement of said pedal into electrical power. a pedal pin extending along a longitudinal reference axis and having a first axial end structured to be coupled to a pedal crank of a bicycle, a pedal body coupled in a freely rotatable manner on said pedal pin thus being able to rotate around said reference axis, at least one internal chamber is made in said pedal pin, having an internal surface extending in the pedal pin along said reference axis coaxial to the same, an electronic measurement system which is designed to determine the mechanical force/power exerted by the cyclist on said pedal during the pedalling and comprises: deformation sensors which are coupled to said pedal pin and are configured in order to provide electrical measurement signals indicative of the mechanical deformation of said pedal pin, electronic means which are electrically connected to said deformation sensors and are configured so as to determine, based on said electrical measurement signals, the mechanical deformation of said pedal pin caused during the pedalling by said mechanical force exerted by the cyclist on the pedal pin through the pedal body, an electric power-supply device which is designed to provide the electrical power for the operation of the electronic measurement system, deformation sensors which are coupled to said pedal pin and are configured in order to provide electrical measurement signals indicative of the mechanical deformation of said pedal pin, electronic means which are electrically connected to said deformation sensors and are configured so as to determine, based on said electrical measurement signals, the mechanical deformation of said pedal pin caused during the pedalling by said mechanical force exerted by the cyclist on the pedal pin through the pedal body, an electric power-supply device which is designed to provide the electrical power for the operation of the electronic measurement system,