spirals each of enamel insulated wire having a 0 17 mm diameter the very low no load loss value is a significant advantage of the device of the present invention indeed given the low value of these losses the alternator according to the present invention may be permanently left coupled and the mechanical disconnection means which had to be provided with conventional bicycle alternators are thus spared on the other hand the alternator may be almost permanently operated at its 1 w power which is negligible with respect to the effort to be provided by the cyclist to maintain his speed on flat ground with an efficiency on the order of 90 so that the available power can be used to permanently recharge a battery that may be used for example when the bicycle is stopped or runs at very low speed the maximum power will only be used when the cyclist desires to use his lighting or other electric equipment of course the alternator operates a variable frequency and voltage which may be disturbing for the power supply of a light if the lighting intensity is desired to be relatively constant electronic regulation means will be provided fig7 illustrates an alternator 100 as described above electrically connected to a load 102 as described above the load 102 may comprise for example a lighting devise or a battery techniques for connecting an alternator 100 as described herein to the load 100 are well known in the art although an alternator has been described in the specific case of the application to a bicycle light this alternator may be used.