Tuesday, March 2, 2010

What is the definition of a bicycle?

I read
with interest, particularly, the section which proposes refinement of the definition of a bicycle:

6. "Bicycle" means a device, including a racing wheelchair,
that is propelled by human power and on which a person may ride and that has
(a) Two tandem wheels, either of which is more than sixteen inches
in diameter,
except that the wheels
may be smaller if the bicycle is foldable.
(b) Three wheels in
contact with the ground, any of which is more than sixteen inches in diameter.
I found the proposed revision troubling. While in the past, I have accepted the 16-inch wheel rule as central to the definition of a bicycle, the proposed change now has me even questioning that. Since parts A and B are the definition of a bicycle, using "bicycle" as part of the proposed revision to part B is semantically problematic. By my read of the revised definition, since the handlebar folds down,the device below could count as a bicycle.

Bike Friday and other similar travel bicycles typically have a 20" wheel, so I'm not sure exactly what the concern is.

Personally, I think that a rotary, human powered, propulsion mechanism is central to the definition of a bicycle. Pushing off with a foot, like with a skateboard, scooter or rollerblades doen't fit this definition but a racing wheelchair and a handcycle would. And if we are going to include trikes as part of bikes, why not quad-wheeled devices?

Based on the revised definition, I can fairly easily imagine contrivances which would technically fit the definition of a bicycle, but which I would think had no business being in traffic.

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