A simple (if not precisely correct) model of the output from the DC brushless controller attached to a spinning electric hub motor bike generator is as a 60 Volt (maximum) battery.
(In order to hit 60 volts a rider has to use a high gear and spin very fast.)
A nice simple online circuit simulator from Univ of Colorado is here http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
Above is the circuit design for the load - 4 parallel strings with (2x 24 volt light bulbs in series). With internal resistance each bulb is around 25 volts and the circuit is pulling ~10 amps. Factoring in motor resistance the circuit is pulling ~600 watts. (Considerably more than most riders can sustain.)