As I began planning a microcar in September 2005, I started
to think about a three-wheeler. If you look at microcar history on microcarmuseum.com you'll see that many microcars
are three-wheelers. But coming fresh to the subject, you might wonder why one wouldn't build a four-wheeler.
It's a more stable configuration, which keeps its width naturally for passenger and cargo carrying, and is well
known and tested.
We pioneers and prototype makers are, to some degree, trapped with three
wheels. We want to go beyond two wheels for reasons of stability, enclosure, year-round use, and user friendliness.
Yet we are blocked from four wheels by the large amount of safety regulations of such cars. And
yet, for a prototype to be tested, seen, and thereby enter vehicle evolution, it needs to roll on the roads, and therefore be
licensed, insured, and inspected. A four wheel car will need dual brake systems, safety glass windows, air bags, impact
bumpers, etc.
These requirements are based on safety, which is good. It's not that
we are sleazes who want to build death-traps! Rather, we need a little slack to try something new, something which
in eventual production will have more safety refinements. Building three wheelers, which are
classified as motorcycles, we have that breathing space.
And once we accept, grudgingly perhaps, that the bureaucrats have
the last word, we get excited about three wheels. Here's why.
Three-wheelers come in two styles: "tadpole" style with two wheels in front,
and "trike" style with two wheels in back. During strong braking, almost all of a vehicle's weight shifts forward. During
braking the tadpole style acts like a four wheeler, with two wheels still able to brake and steer.
The trike style, however, acts more like a motorcycle, and is prone to tip sideways. So, if we are going to three wheels with year-round, user friendly, safe driving in mind--we
end up with tadpole style.
We soon encounter other advantages: with only one driving wheel in
the back, you don't need a differential, and you can use an unmodified motorcycle or motorscooter drive system. When
I'm putzing in Moonbeam 50 miles from home, I'm so glad my drivetrain was designed by hot-shots in Tokyo, instead of a shade-tree
mechanic named Jory Squibb!
Finally with this configuation, you have cut down on a propulsion
wheel, but not on a steering wheel, which makes for safety.
Are you warming up to three-wheelers? They're quite common in
China, where a good dozen passenger-carrying small cars are manufactured. One looks like the picture
below. They cost between $1200 and $1800 FOB China, and some run on CNG, natural gas!
But I
am pretty sure the car below is unsafe, being trike style, and that--if true--is significant. The car's evolutionary
history comes from the tricycle rickshaw, through the motorized tricycle truck, and then naturally on to this first-generation passenger
car. All are trike style.
When I was at the altcarexpo in Santa Monica in December 2006, I got a good chance
to inspect a "Zap" a USA-installed electric conversion of a Chinese three wheeler. I feel quite cautious about
the quality of the car. Price is not everything, but surely before long, small chinese cars will be here in numbers.
