the stability of bicycles

[palmer@sfu.ca (Leigh Palmer)]

> Oh really!  I'm a bit surprised by this.  What explanation do
> they give for the reason for the stability of the bicycle?

They? I thought everyone knew - the bicycle is unstable. It
remains upright moving in a straight line only by active control
by its rider, who steers it to keep it from falling over. A
bicycle moving on a curve is stabilized by steering geometry.
If you believe that a bicycle is stable you probably don't ride
much. As an exercise try riding a painted straight line on
horizontal pavement for 100 meters or so; you'll see. I used to
be able to do so; I no longer can because I cycle much less now
than I used to (Friday was my first day commuting to school by
bike since 1995). There are other experiments one can do to
demonstrate aspects of the nature of bicycle steering. It is
far from being mechanically trivial.

Both Sharp and Whitt & Wilson treat stability in their books,
the latter in some considerable detail, and I recommend them.

Leigh