A pedal for bicycles comprising a pedal-pin, which extends along a reference axis, and a pedal-body, which is coupled to the pedal-pin in a rotary free manner. An internal chamber is obtained in the pedal-pin and has an internal surface, which extends along the reference axis approximately coaxial to the latter. The pedal further comprises strain gauges, which are configured to detect electrical parameters indicative of the mechanical deformation of the pedal-pin, and an electronic circuit, which is configured to determine, based on the electrical parameters, the mechanical deformation of the pedal-pin. The strain gauges are rigidly fixed on the internal surface of the internal chamber by a thin fixing layer of adhesive material.