Dynamo for bicycles

A hub dynamo connectable to a wheel of a bicycle, comprising:

• an electric machine operable alternatively as a generator and as a motor;
• one or more batteries connected to the electric machine to exchange energy with the electric machine;
• a closure body connectable to the wheel to rotate coaxially with the wheel, the closure body internally containing the electric machine and the one or more batteries;
• the closure body being free of connectors for connecting the one or more batteries to external energy sources, so that the one or more batteries are only rechargeable by the electric machine acting as the generator due to rotation of the wheel;
• a control unit configured for commanding the electric machine:
• according to a first mode, wherein the electric machine acts as the generator and converts a rotational mechanical energy of the wheel into recovered electric energy to be stored in the one or more batteries, the first mode being further configurable by the control unit according to a first recovered energy level and a second recovered energy level, wherein the first recovered energy level is less than the second recovered energy level under a same motion condition of the bicycle;
• according to a second mode, wherein the electric machine acts as the motor and delivers additional power to the wheel by withdrawing energy from the one or more batteries;
• wherein the control unit is configured to automatically select between at least one chosen from 1) the first mode and the second mode and 2) the first energy recovery level and the second energy recovery level, at least partly based on signals arriving from at least one chosen from a sensor and one or more command members operatively connected to the control unit and commandable by a user for selecting between the at least one chosen from 1) the first mode and the second mode and 2) the first energy recovery level and the second energy recovery level;
• a charge sensor for detecting a charge level of the one or more batteries, operatively connected to the control unit and configured for generating a signal representative of the charge state of the one or more batteries;
• wherein the control unit is configured for commanding the electric machine according to the first mode such that, under the same motion conditions of the bicycle, the recovered electrical energy increases as the charge level of the one or more batteries decreases.