Not true, t2andreo, I have a battery assisted bicycle which has three modes - pedalling alone, battery assisted pedalling or battery-powered alone. I have mainly used the latter two of those modes. On battery-powered mode alone I have a safe range of about 15km+ at a speed of around 30km per hour on the flat. If I didn't want to go quite so far and wished to travel faster I can easily maintain a speed of around 35km per hour.
As to pedalling alone, I would not contemplate doing so for as you observe these bicycles are heavy.
But as a fun mode of transport, locally here, it is useful and fun for nipping down to the local shop and pub, 3kms away, and smiling evilly as you zoom past mamils (middle-aged men in lycra) on their incredibly expensive racing bikes as they labour up the local hills!
As to using one on the Camino - forget it!
I stand corrected. When I wrote my post, I felt certain that someone from the bicycle savvy countries of the world would catch me up.
However, we likely agree that riding into Santiago on a device that requires NO manual effort (as in pedaling) or pushing is riding a motorized contrivance and would not be considered "legal" in the pilgrimage sense. But, riding a device that requires manual effort to move forward, even if partially mechanically assisted, would likely be ruled "in bounds" provided that, the device could never be ridden on electric or other motive power not requiring manual effort.
Obviously, only the Pilgrim Office can make the final determination. But my sense is that they would rule a battery-assisted pedaling-required at all times bicycle "legal," while running "out of bounds" any bicycle-like or scooter-like device that could be ridden solely on stored motive power, electricity (battery), petroleum or other liquid fuel, etc.
I was initially wrong. I was simply ignorant of all the options available on the market. But we both fundamentally agree. That said, I feel we can all agree that these devices likely have no place on the Camino proper as they are either too heavy, or simply not up to the ruggedness required.
The "Elliptigo" device quoted above behaves much in the same way as a regular bicycle. However instead of having a round crank with two opposed pedals providing power through gears and a chain or driveshaft, it uses the up and down motion of an elliptical trainer or stair-step machine to move the wheels.
My opinion would be that this is simply another form of bicycle and would likely be treated as such by the pilgrim office. You could make a simple argument that says pedaling up and down is fundamentally no different than pedaling round and round. However, the rest of the bike appears far better suited for a road trip than a Camino over-land.
Thank you for the correction.