Recharging an Electric Bike on the Move

“Many years ago I cycled to Nice from home in the Birmingham area. Due to a road accident, I am not able to do such a silly thing again, though I would like to.Would it be possible and legal to tow a small generator behind an electric bike, leaving it running whilst riding?”

Anthony Skidmore
Halesowen,West Midlands

…we’re talking hybrid petrol/electric/human power… [but] the roar of a petrol engine would be quite out of keeping…

This question should really be broken into two parts – legal and technical. Under UK law (the Electrically Assisted Pedal Cycles Regulations 1983) an electric bicycle is defined as a machine where ‘The motor assistance must be provided by an electric motor.’ Which sounds fine, except that, ‘Propulsion by an internal combustion engine is not permitted’. Now, of course, this wording is intended to outlaw direct drive from an internal combustion engine.What you propose is, effectively, a mobile battery charger, topping up a conventional battery.This would be another interesting matter for the courts to decide. One assumes the legal debate would centre on this concept of ‘propulsion’, thus I suspect the trailer would make no difference – if this form of charging was adjudged to be within the law, it would also be legal carried on the bicycle.

Technically, there are no great complications:We’re talking hybrid petrol/electric/human power here. Such a vehicle could run on human power in flat urban areas, human and electric power on hills, and top-up the battery from the internal combustion power source as and when required. Range would be quite considerable, because fuel consumption would be nil on many journeys. But on the open road, the roar of a petrol engine would be quite out of keeping, so it’s hard to see the advantages over a small motorcycle for longer journeys.

Once again, one suspects that fuel cells may soon render such dramatic steps unnecessary. Provided an internal combustion engine is not involved, the regulations seem to allow any form of electrical power generation, from solar to nuclear. Neither of these extremes are very practical, but a small fuel cell probably would be.