Method for measuring at least one speed and/or distance travelled by a bicycle when in use by a user, which measurement is carried out by means of at least two measuring circuits (3, 3'), each measuring circuit comprising a magnetic sensor, the two measuring circuits being arranged on the same side of the wheel or rim or on two opposite sides of the wheel or rim of the bicycle and offset by 180° from each other, and at least two permanent magnets (2, 2') arranged on a frame portion or a fork for mounting the freely rotating wheel, each permanent magnet (2, 2') being arranged on the frame portion or the fork at the same distance from the axis of rotation of the wheel as each measuring circuit (3, 3') in order to face the respective measuring circuit (3, 3') as it passes during rotation of the wheel, the method comprising the steps of: - setting the bicycle in motion on a path with the wheel rotating with the measuring circuits (3, 3'), - detecting the passage of the magnetic sensor of each measuring circuit (3, 3') opposite the respective permanent magnet (2, 2') by generating an induced voltage pulse each time each rotating measuring circuit (3, 3') passes, - rectifying the voltage generated by the magnetic sensor by means of a rectifier and storing the rectified voltage on a smoothing capacitor (C L) to supply the respective measuring circuit (3, 3'), - computing a speed and/or distance travelled by the bicycle in a computing unit, which is clocked by a quartz horological oscillator of the measuring circuit, on the basis of the induced voltage pulses received over time from the magnetic sensor and given the known value of the diameter of the wheel of the bicycle, and - storing speed and/or distance travelled measurements obtained by integration, in the computing unit of each measuring circuit (3, 3') in a non-volatile memory of each measuring circuit (3, 3'), and - wirelessly transmitting one or more speed and/or distance measurements computed in the computing unit of each measuring circuit (3, 3') to a portable device carried by the user or on part of the bicycle by a signal transmission-reception unit linked to an antenna of each measuring circuit (3, 3'). - setting the bicycle in motion on a path with the wheel rotating with the measuring circuits (3, 3'), - detecting the passage of the magnetic sensor of each measuring circuit (3, 3') opposite the respective permanent magnet (2, 2') by generating an induced voltage pulse each time each rotating measuring circuit (3, 3') passes, - rectifying the voltage generated by the magnetic sensor by means of a rectifier and storing the rectified voltage on a smoothing capacitor (C L) to supply the respective measuring circuit (3, 3'), - computing a speed and/or distance travelled by the bicycle in a computing unit, which is clocked by a quartz horological oscillator of the measuring circuit, on the basis of the induced voltage pulses received over time from the magnetic sensor and given the known value of the diameter of the wheel of the bicycle, and - storing speed and/or distance travelled measurements obtained by integration, in the computing unit of each measuring circuit (3, 3') in a non-volatile memory of each measuring circuit (3, 3'), and - wirelessly transmitting one or more speed and/or distance measurements computed in the computing unit of each measuring circuit (3, 3') to a portable device carried by the user or on part of the bicycle by a signal transmission-reception unit linked to an antenna of each measuring circuit (3, 3').