HUMAN POWER
T E C H N I C A L J O U R N A L O F T H E I H P VA
NUMBER 50, SPRING 2000
Summaries of articles in this issue; mast . . . . . . . . . . . . . . . . 2 Contributions to Human Power . . . . . . . . . . . . . . . . . . . . . . . 2
Articles
On the efficiency of bicycle chain drives James B. Spicer and others . . . . . . . . . . . . . . . . . . . . . . . . . 3 Offset rims reduce the amount of dish Vernon Forbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Rolling resistance of bicycle tyres John Lafford . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Note on John Lafford’s paper and spreadsheet Jim Papadopoulos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Reply to Jim Papadopoulos John Lafford . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Technical notes
Power requirements for laid-back recumbents Bert Hoge and Jeroen Schasfoort in HPV nieuws Report and comment by Dave Wilson . . . . . . . . . . . . . . . . 18 My propeller theory E. Eugene Larrabee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Reviews
Feet on!: pedal-powered museum exhibit Michael Eliasohn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Human power: the forgotten energy Arnfried Schmitz, reviewed by Dave Wilson. . . . . . . . . . 22
Editorial
Cycle Vision, Ronald van Waveren . . . . . . . . . . . . . . . . . . . . 23
Letters
Number 50 Spring 2000
$5.50
Update, Anil Rajvanshi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Supplement to velocar variations, Arnfried Schmitz. . . . . 22 Kudos, Chet Kyle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Number 50
HUMAN POWER
Spring 2000
On the efficiency of bicycle chain drives
$5.50/IHPVA members, $4.00
beautifully produced Netherlands counterpart to Human Power: HPV nieuws. They showed, by testing a range of Dutch recumbent bikes, that the aerodynamic drag decreases as the angle of reclining increases. My propeller theory Gene Larrabee, whom Human Power named “Mr. Propeller” many years ago, summarizes his propeller theories and the developments that have resulted from them. He also pays tribute to those who inspired him and gave him the basic theories on which he built. Was Isaac Newton the first to state that we all stand on the shoulders of giants? Feet-on! review Mike Eliasohn writes a delightful review of what sounds to have been an equally delightful and truly interactive museum exhibit devoted to human power. Human power: the forgotten energy Your editor reviews a small fascinating book by Arnfried Schmitz, already wellknown in these pages, on the origins of HPVs in France, on the characters of the protagonists, and (very modestly) on his own part in the revival of interest in these wonderful vehicles. Editorial from the Netherlands Ronald van Waveren, chair of the Netherlands HPV association, writes a guest editorial about the astonishing numbers of recumbent bicycles and HPVs in the Netherlands, and in particular about the annual celebration known as “Cycle Vision.” Through delays in our publication we are too late to encourage you to visit this exciting event this year, but we hope that you will do so next year…. Letters include kind words from Chet Kyle; comments by Anil Rajvanshi on the publication of his article on rickshaws in the last issue (Human Power 49); and comments and corrections by Arnfried Schmitz on his article “Velocar variations”, also in the last issue.

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