Re: the stability of bicycles

[palmer@sfu.ca (Leigh Palmer)]

>   During my own period of maniacal cycling -about 10 years and forty
> pounds ago- I read about a bicylce that had been built with a dummy
> third wheel that didn't touch the ground but which rotated
> opposite to the direction of the other wheels in such a way that
> the total angular momentum of the three wheels was zero. Ths
> mutant bicycle was perfectly stable. Unfortunately, I can't
> recall a reference.

That's David Jones, a chemist. He built four experimental bicycles.
His work was published in Physics Today, but there is a good summary
of it in the "Bicycling Science" book. I should point out that the
bicycle you described wasn't stable; it was rideable even though it
lacked a front wheel gyroscopic moment. Actually the very most
expensive and responsive bicycles are equipped with very lightweight
wheels which, consequently, have smaller gyroscopic moments.

Leigh