Bicycles are the delightful vehicles that they are, partly because they are not as fast as a car, a train or a speeding bullet. If their motive power were to be increased so that they were capable of substantially faster average or top speeds, they would then require stronger brakes, more suspension, a heavier frame, stronger tires and better traction; in other words, they would become mopeds or motorcycles. They would be riskier to ride, and would pose more danger to pedestrians. They would be an increment less neighborhood-friendly. They would no longer be just bicycles.

When in trained condition, I can produce 100 watts for most of a long ride, 250 watts in a hard pull and 500 watts in a short sprint. For me, then, anything over the threshold of 250-300 watts of assist, if used continuously, becomes the prime mover of my cycle, changing it from a bicycle to something else. This something else is not dark and sinister; it is just different.

The bicycle purist in me, my inner fascist, convinced that my position is the only correct one, finds this admission somewhat distasteful. We have to listen, however, to those people who say that, at certain times, they very much want their cycle to be a faster traveler, a quicker negotiator of traffic, an easier hill-climbing commuter, or even just a less demanding recreational vehicle. Certainly there is a place for power assisted cycles.

In fact, I wish my car were a power assisted cycle—a velo car—and I think my neighborhood, society and world would be better off if it were.

We can conceptually divide velo-car type vehicles into two classes. The first is the ‘velomobile’, in which light weight is preserved as much as possible and aerodynamic efficiency is increased as much as possible, in order to allow pure human power to attain the greatest possible speed and range that it can. The second is the ‘velocar’, in which utility, cargo or passenger capacity, user comfort and ease of use are maximized, even if the vehicle becomes no longer capable of being effectively powered by muscles alone.
I assert that the vehicle of the first category, the velomobile, remains essentially the same as a bicycle, and should be treated as such.

The second category needs to have an upper limit to its power assist component, lest the lust for power spiral out of control, even to the point that the velocar mutates into a Volkswagen. You can buy assist systems that offer 1000 to 1500 watts of power, which effectively turn the bicycle into a pedal-optional ultralight electric motorcycle. Again, this is not necessarily a bad thing, but it just ain’t a bike anymore. I think that a logical legal boundary and design limitation for the velocar class would be to keep the power assist as an equal contributor to an athletic rider, but no more. Those less athletic persons who need the most help to move this probably-heavier and probably-less-aerodynamic micro-vehicle would find that 300 watts could move it–with their help, or even by itself if they are physically incapacitated–at a decent bicycle-like velocity. With this limitation respected, the velocar will remain, just as does the velomobile, a vehicle functionally and legally equivalent to a bicycle.