A power control circuit having an input for receiving power from a power source and an output for driving a bicycle electromotive unit comprises a storage unit; a first switching element disposed between the storage unit and the output; a voltage sensor that senses a voltage associated with the storage unit; and a switch control circuit operatively coupled to the voltage sensor and to the first switching element to disable the communication of power to the output when the voltage associated with the storage unit is less than a first reference voltage and to enable the communication of power to the output when the voltage associated with the storage unit is greater than the first reference voltage. After the switch control circuit enables the communication of power to the output, the switch control circuit may maintain the communication of power to the output when the voltage associated with the storage unit falls below the first reference voltage and is above a second reference voltage. A second switching element may be disposed between the input and the storage unit, wherein the switch control circuit is operatively coupled to the second switching element to enable the communication of power to the storage unit when the voltage associated with the storage unit is less than the first reference voltage and to disable the communication of power to the storage unit when the voltage associated with the storage unit is greater than a third reference voltage.