Now that's quite interesting. I've often wondered if having an onboard generator would work... kinda like a diesel electric locomotive. I think that sort of arrangement would be far more efficient than the current crop of hybrid vehicles. Using an all electric drive with a diesel/gas burning generator driving a generator eliminates the need for a transmission. The generator charges the battery bank while the car is coasting or sitting still and provides motive power at cruising speeds. The batteries provide an extra kick when starting up from a dead stop and accelerating.
On an electric bike, adding an onboard generator eliminates most concerns about range. The question to noodle out is how little battery and how small a generator you can get away with and still keep the bike & rider moving.