The stability of the bicycle
APR 01, 1970
Tired of quantum electrodynamics, Brillouin zones, Regge poles? Try this old, unsolved problem in dynamics—how does a bike work?
DOI: 10.1063/1.3022064
ALMOST EVERYONE can ride a bicycle, yet apparently no one knows how they do it. I believe that the apparent simplicity and ease of the trick conceals much unrecognized subtlety, and I have spent some time and effort trying to discover the reasons for the bicycle’s stability. Published theory on the topic is sketchy and presented mainly without experimental verification. In my investigations I hoped to identify the stabilizing features of normal bicycles by constructing abnormal ones lacking selected features (see figure 1). The failure of early unridable bicycles led me to a careful consideration of steering geometry, from which—with the aid of computer calculations—I designed and constructed an inherently unstable bicycle.
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References
1. S. Timoshenko, D. H. Young, Advanced Dynamics, McGraw‐Hill, New York (1948), page 239.
2. A. Gray, A Treatise on Gyrostatics and Rotational Motion, Dover, New York (1959), page 146.
3. J. P. den Hartog, Mechanics, Dover, New York (1961), page 328.
4. K. I. T. Richardson, The Gyroscope Applied, Hutchinson, London (1954), page 42.
5. R. H. Pearsall, Proc. Inst. Automobile Eng. 17, 395 (1922).
6. R. A. Wilson‐Jones, Proc. Inst. Mech. Eng. (Automobile division), 1951–52 page 191.
7. Encyclopaedia Britannica (1957 edition), entry under “Bicycle.”
© 1970 American Institute of Physics
