- Oct 25, 2006
The 250 watts is a rating, little more then a legal nicety. In practice the actual power obtainable usually ranges from about 400 to 600 watts and can even be higher. The ways of measuring it set out in technical document EN15194 allow considerable flexibility both of measurement and interpretation for entirely practical reasons, since a fixed limit of actual 250 watts would make pedelecs virtually useless for many.Thank you for a very full and interesting post. I know that the UK legal motor size limit is 250W but am puzzled how Bosch manage to make a whole range of motors at prices that go up with torque from 40Nm up to 85Nm, are these all 250W, just that the more expensive ones have more powerful watts?
I can illustrate how extreme this can become with the example of the Lynch motor for pedicabs (powered bicycle rickshaws) used to carry two or three passengers by the cyclist pedalling. That motor is also nominally 250 watts and in it's upper speed ranges to about 8 to 10 mph it does only produce a few hundred watts.
But when hitting a hill with passengers on board, as it slows right down the power outputted rises with reducing speed and can reach almost 5 kilowatts with immense torque at a very slow crawl. With the rider having a suitably low gear to also pedal assist efficiently at a crawl, it can climb any reasonable hill with an all up weight of over 400 kilogrammes, albeit very slowly.
So in a nutshell, the regulations allow pedelecs to be practical for every use with turning them into speed machines. Cycles Maximus, one of the producers of such a pedicab also made a 5 cwt (250 kilo) payload van version.