Sunday, 30 March, 2003

Bicycling Science

Considering the material, Bicycling Science by Frank Rowland Whitt and David Gordon Wilson is a surprisingly good read.  The book is exactly what the title implies—a study of the science behind bicycling, including human power generation, bicycle physics (wind resistance, friction, wheel physics, braking, etc.), and mechanics and mechanisms (power transmission).  The book includes chapters on the history of bicycles, unusual human-powered machines, and a look into the future of human-powered machines.  My only complaint with the book is its age.  It was written in 1980, so all of the advances in materials science and other innovations of the bicycle aren't included.  Nonetheless, the basic science of bicycling hasn't changed in 100 years, so most of the information is still relevant.

Many of the discussions explain the limiting factors not only of bicycling or human powered machines, but of power generation in general.  It's interesting to note, for example, that if you double your speed, you cube the power requirement.  As I've pointed out before, the primary impediments to motion on the ground are wind resistance and rolling friction.  Power transmission on the bicycle itself is surprisingly efficient—in the 95% to 98% range.  But the human body's efficiency is in the range of 23% to 28% efficient.  That is, only about one-fourth of the energy you expend is converted into useful work, making a person on a bicycle approximately 25% efficient—about the same as an automobile.

The book is well-researched, and full of charts, tables, and figures that illustrate the authors' points.  The writing is slightly more formal than I'd prefer, but not dry by any means.  If you're at all interested in the science behind bicycling, you should read this book.