That's a <i>terrible</i> idea, for both principled and pragmatic reasons.<p>Bicycles are the most energy efficient vehicles ever invented, getting approximately 1,400 mpg equivalent in fuel economy. They produce no emissions (other than wear on tires and brake pads) at the tailpipe. They cause minimal wear and tear on roads. They take up much less space than cars, both when traveling and when parked. Regular cycling is associated with several extra years in life expectancy, reducing lifetime medical costs for cyclists.<p>Also, the cost or providing cycling infrastructure is only a tiny fraction of the cost of providing automobile infrastructure. You can construct a permanent, continuous cycling network in a city for about what the city's road system costs in maintenance for one year.<p>In short, bicycles produce almost no negative externalities and significant positive externalities, so it makes no sense to punish people for cycling with financial or regulatory barriers.<p>Further, as the rate of cycling goes up, the rate of cycling casualties goes down, and the overall casualty risk for cyclists is lower than for motorists; so it is in everyone's pragmatic interest to encourage as much cycling as possible.
I'm in Japan at the moment and bikes are already fairly strictly controlled. You have to register it with the authorities when you buy it and there are several places near major train stations where you are specifically not allowed to park your bike.<p>In addition, while there are often bikes lying around the place, you can get stopped by the police to show that the bike you're riding belongs to you.<p>With the inner city crowding you get in places such as Tokyo this should come as no surprise. However, there isn't much of a bike infrastructure - you have to share the same narrow roads that cars and pedestrians take.
The taxation idea doesn't hold water when you look at it in detail. I can't remember the reference now, but the point was made that because most road building is funded by sources that have nothing to do with cars (local taxes, etc) non-drivers are actually <i>subsidizing</i> drivers. Cyclists, along with pedestrians, actually pay more than their fair share of the cost, given that they cause practically no road wear and a minimum of the construction costs.
I'm just about ready to release a rant about ignorant, car-culture addicted North-Americans that just can't get used to anything other than suburbs, drive-thrus and SUV's (I believe you can even get married in a car in the U.S. etc.).<p>Oh wow, a bicycle: BIG DEAL. People in Europe just use em everyday. No, you don't need insurance, or taxes or any special regulations to deal with bicycles. Just USE EM.<p>It's almost like watching somebody seeing chop-sticks for the first time... Oh, they could be dangerous, don't swallow them, we need warning signs on them to prevent injuries etc. etc.
Bikes should be treated like cars in one way: there should be a formula for the amount of wear and tear a vehicle makes on a road surface that is used to levy an annual tax on all vehicle owners. But if the tax is below a certain floor, no tax is due. Which would end up meaning, in practice, that motor vehicles are taxed, and heavier motor vehicles are taxed more heavily, but bicycles pay no tax.