Electric bikes – How Many Watts?

Professor Pivot“There seems to be some confusion with regard to the legal power of electric bikes today. I am hearing that the maximum power permitted is now 250w and not 200w. Is this correct?”

Alan D. Shaw

Once upon a time, the law was the law and we all knew where we stood, but today things are a bit more complicated, thanks in this case to Europe. Basically, we now have both British law, allowing 200-watt motors for bicycles (and 250 watts for tandems and trikes), and European law (250 watts throughout) on the statute books at the same time, resulting in confusion as to which should take precedence.The same applies to the legality of so-called ‘e-bikes’ that allow the motor to be operated without pedalling.These are legal under British law, but illegal under European law. Neither the Department for Transport or Department for Trade & Industry seem willing or able to answer these questions, even suggesting rather unhelpfully that the matter should be settled in the courts!

To make things even more complicated, electric motors are rated on a ‘continuous’ basis, so that 200-250 watts rating bears little relation to the actual power at the wheel. A continuous rating is, crudely, the power that a motor (or indeed, a human) can produce all day. It can be precisely defined, but I have yet to find a British, European or ISO definition, although one, or perhaps several definitions, must exist.

Study the graphs in A to B road tests, and you will see that most electric bicycles produce in excess of 400 watts, and peak outputs of 1,000 watts or more are not uncommon.These powerful motors were designed for the US market, where some States allow motors of ‘up to 1,000 watts’ and a top assisted speed of 20mph.With the collapse of the US electric bike market, they’re now being sold elsewhere, and it’s a measure of how confused the situation has become that these machines are being openly traded in the UK. Personally, I do not feel that a normal bicycle has the lights, brakes and other equipment to deal with these higher speeds, and with long-range fuel cells not so far off, I would prefer to see a new hybrid bicycle/moped vehicle class, allowing greater speed, but with compulsory insurance and so forth. [As in Switzerland and elsewhere, see News, Eds].

For now, provided your electric bicycle does not exceed 15mph under power (24km/h in Europe!), or burn rubber at the lights, you can buy and use just about anything you like. At some point, an innocent bicyclist will be stopped on a US or European machine and hauled before the courts. Barring appeals, this will give a clear precedent for cycle trade, police and public to follow.

One wonders how the Department for Transport sees its role? It is quite absurd that the official transport bodies are unable to settle this matter, but as we know all too well, bicycles are hardly a top transport priority.