: The Massachussets Institute of Technology
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We intended the first edition of this book "to be of interest to all mechanically inquisitive bicyclists, as well as to teachers of elementary mechanics or physiology, and to engineers and others working on approaches to lessen our dependence on high-energy-consumption transportation." Since we wrote those words, in 1974, several developments have seemed to confirm that the wave of popularity of the bicycle that started in the early 1970s was not just a short-term craze. The forced rise in world oil prices and the occasional disappearance of easily available gasoline (more significant in the United States) at last convinced many people that a long-term change was required in the affluent way of life experienced by many in the technologically advanced countries. Bicycling began to be taken more seriously P- an alternative to the use of the automobile and public transit for commuting. Another development with strong effects— good and bad—was the New York City transit strike of 1980. On the good side was the discovery by tens of thousands of people that commuting by bicycle was possible, and by many that it was pleasant. On the negative side, there were many accidents between bicyclists and pedestrians and between motor vehicles and bicycles, partly because of nonexistent or ill-conceived traffic arrangements for bicycles. A third development, wholly beneficial, was the creation in 1974-75 of a new class of cycle racing. The International Human-Powered Vehicle Association, formed by Chester Kyle and a small group of fellow enthusiasts in California, sponsors speed trials and other races in which there are no restrictions on vehicle design other than that there must be no energy storage. The xiii Preface speeds already reached by the application of sophisticated aerodynamic fairings and supine or recumbent riding positions alone would have seemed incredible a decade ago, and yet it seems likely that 30 m/sec (67 mph) will be attained within a decade. Enthusiasm for this new sport is spreading and growing in the United States and in Europe. The attendance at the first racing meet in Britain in 1980 was more than for all the previous U.S. meets combined. This form of racing is certain to bring about a resumption in the development of bicycles for everyday use. A stream of new ideas was encouraged by bicycle racing in the 1865-1895 period, but this stream was then reduced to a trickle by the adoption of highly restrictive rules for racing. Now we see new developments in bicycle technology coming almost as a flood. These developments have been largely responsible for this second edition of Bicycling Science. We have added a large amount of new information about human power output under various conditions, and have revised and expanded the sections on aerodynamic, wheel, and bearing losses. These inputs and outputs have been combined in a new chapter on the prediction of speeds for typical and hypothetical vehicles for various levels of power input. Thus we have tried to serve the new wave of designers, planners, and builders of vehicles both for racing and for everyday commuting use with data and methods that should further the designing of optimum vehicles. We have also added a short chapter on the technological history of bicycles and tricycles, partly because it is a fascinating story and partly because awareness of what has been tried before can help to preclude the repetition of expensive mistakes. In this respect we have the same aim as "Professor" Archibald Sharp (who was in fact an instructor in engineering design at a London technical college), who wrote his classic Bicycles and Tricycles at a time (1896) xiv Preface when, as at present, people were experimenting with all manner of variations of cycle design and construction. In his preface Sharp wrote that "there are many frames on the market which evince on the part of their designers utter ignorance of mechanical science," and that "if the present work is the means of influencing makers, or purchasers, to such an extent as to make the manufacture and sale of such mechanical monstrosities in the future more difficult than it has been in the past, the author will regard his labors as having been entirely successful." Other good books on the science of bicycling were published by authors such as R. P. Scott and C. Bourlet in the same period. From that time until the present revival of interest in bicycling, technical authors turned their attention toward automobiles, airplanes, and other apparently more exciting challenges. The stagnation of bicycle design, brought about largely by restrictive rules for racing, was aided by the lack of interest of publishers (and, perhaps, potential readers) and by the astonishing new transportation competitors—subways, cable and electric streetcars, motorcycles, automobiles, the railroads then reaching over 100 mph (about 50 m/sec), airships, and the early aircraft. We point out in the first chapter that a similar, though shorter, period of stagnation occurred after 1825, and that this was probably due to somewhat similar excitement about the potential of railroad transportation. Inventive people making improved bicycles in such periods of stagnation found that their concepts (and their manuscripts) fell on stony ground. We as authors and bicyclists are fortunate to be living at a time when bicycle design is undergoing considerable change. In providing a technical guide, we have tried to start at all times from basic principles—which are, in general, the laws of physics. We have been concerned principally with dynamics rather than with statxv Preface ics. We have given raw data in those many cases where the final answer, if there ever is such a conclusion to research, is not yet known. And occasionally we have made our own estimates. Some readers may be interested to learn how this book came to be written. Frank Whitt, who is a chemical engineer, had been a contributor to (and for a period the technical editor of) Cycle Touring (Cyclists' Touring Club, U.K.) and had contributed technical papers to symposia and articles to magazines such as Bicycling. He put these together into the beginnings of a book. David Wilson was teaching mechanicalengineering design at the Massachusetts Institute of Technology, using bicycles as occasional examples and supervising some undergraduate projects and theses. He had in Britain a small savings account which the Bank of England would not allow to be transferred to the United States. With the help of the journal Engineering, and with prize money from the savings account and a contribution from Liberty Mutual Insurance, he organized in 1967 an international competition for developments in human-powered transportation. Whitt was one of the 73 entrants. They met some time after the competition was completed in 1969. Subsequently, Whitt asked Wilson if he could find an American publisher for his manuscript. He had not been successful in this endeavor in Britain, and Wilson at first did no better in the United States. Publishers felt that, whatever the quality of a book on bicycling science, the potential readership was so small that the considerable exenditure of publishing the book was not justified. Then came the 1970s and the revival of interest in bicycling. There was still no sign of any change in bicycle design, but Frank Satlow of the MIT Press decided to take a long shot by proposing that the book be adopted. The manuscript was accepted on the condition that Wilxvi Preface son add to it the results of the 1967-69 design competition and any relevant research data, and edit the whole book. That first edition was published in hard cover in 1975 and in paperback in 1977. The continuing popularity of bicycling since then, the wealth of new developments and data, and in particular the intense interest in new types of vehicles made us wish almost immediately that we could rewrite the book. We were, therefore, delighted when Frank Satlow asked us if we would like to work on a second edition. As intimated above, although this is called a second edition, it is really a new book in scope and style; we hope that it will be received with the same goodwill and grace as was the first. This preface is being written, sadly, by David Wilson alone. Frank Whitt suffered a paralyzing stroke in mid-1981, and as of the time of writing (September 1981) he has not yet been able to talk or to write. He is making slow progress, and it is hoped that he will be back with his insights, his experimental and design skills, and his wealth of information to contribute to us all. He is greatly missed.