Switches and more particularly electrical circuitry of a bicycle

The present invention relates to a switch with an electric energy generating means (6) which is arranged at the switch (5) to generate, upon actuation of the switch (5) electrical energy, comprising a shaft (12) with a permanent magnet (13) wherein said power generating means (6) has a first U-shaped ferrite core (11) having a first coil assembly (14) having at least one coil (15, 16), said shaft (12) is displaceable in the axial direction of the shaft, in such a way in that the permanent magnet (13) and the first ferrite core (11) form a closed circuit.