Somethings are almost entirely about context. I think motorised bicycles are definitely one of them.
To begin with, I think some distinction should be made between the electric powered boffins and the petrol powered, two-stroke, bad boys. To begin with, all two stroke engine users set themselves apart from ‘normal responsible behavior’ by using the most noisy means of power available to them, but noise aside, both varieties of powered bicycle have problems that set them significantly apart from other bicycles.
Petrol powered bicycles have been with us for a long time (http://en.wikipedia.org/wiki/Timeline_of_motorized_bicycle_history), and recently seem to have found new devotees taking advantage of the combined affordability of a bicycle and power of the 2-stroke engine. In evolutionary terms they fall somewhere between bicycle and motorcycle, but having lost the grace and simplicity of the bicycle and having none of the utility of a motorcycle, they seem to the casual observer to be the worst of two worlds, spreading noise, oily smoke and the potential for limb tearing accidents at every turn. It is lucky that they make so much noise, because if they were silent they’d probably kill many unsuspecting bicycle path users. If you are hard of hearing, or too young to know better, you are at risk from these cycle path psychopaths.
Silence brings us to the electric motor, the young, geeky cousin of the powered bicycle world. This is a very different animal, but because of it’s speed and stealth, presents a clear and present danger to anyone using a cycleway, deaf, young or otherwise. Electric bicycles are unforgivably uncool, even with the potential to have them powered from something like solar power, but make no mistake, if you don’t spot them first, they are no slouches and can be upon you very quickly. The true horror of these vehicles is the potential to be knocked over by someone on an electric bicycle – the shame of it all! Given that you’d never actually tell anyone about being mown down by an electric bicycle, I believe injuries from these silent menaces go under reported. The one saving grace of electric bicycles is that they could be a stepping stone in the development of something else – lets keep our fingers crossed.
The biggest problem with powered bicycles is of course their owners, which in a round about way, brings us back to my original argument that motorised bicycles are about context. Many riders of motorised bicycles seem to feel that because what they are riding isn’t as cool, fun or useful as a motorcycle, they should be allowed to use cycle paths. This is patently wrong. They should take their place, at the bottom of the food chain, on the roads with other powered vehicles. They are counter to the reasoning of cycle paths more broadly, which are engineered to separate cyclists from motor-ists. The cycle path context is wrong for powered transport of this kind. On the road however they seem wildly appropriate, using less space, energy and materials to get the passenger from A to B and would be less deadly in the case of mishap.