Bicycle Quarterly has published a detailed article about the development of the first Campagnolo parallelogram derailleur, the Gran Sport. The story begins in the late 1940s, when Tullio Campagnolo realized that his Cambio Corsa (shifting system) was reaching the end of its lifespan. He sensed that modern derailleurs, like those used by cyclotourists, would be found on future racing bikes. After evaluating the Nivex parallelogram derailleurs, he designed his first parallelogram derailleur. In 1950 and 1951, small series of pre-production models were made as Campagnolo fine-tuned the derailleurs. In 1953, Campagnolo introduced the final production "Gran Sport," which remained unchanged for many years. Even the 1980s Super Record derailleurs use the same basic geometry of the Gran Sport, albeit with a modified pulley cage pivot location and lighter materials.
The first prototypes were made from brass, with flat cage plates that lacked strength.
The 1953 production version.The full article of the history of the Campagnolo Gran Sport with additional photos and detailed drawings, and another article of the milestones in the development of parallelogram derailleurs, can be found at: http://www.vintagebicyclepress.com/samples.html. Scroll down to the "Cycling History" section to find these two articles (which will be in a pdf format).
Bicycle Quarterly is published 4 times a year, each issue a treasure trove of information.
Photos: H. Ichikawa, ©Bicycle Quarterly (used by permission)
Stories for the Italian Cycling Journal welcome; contact me at veronaman@gmail.com. There are more than 1,100 stories in this blog; the search feature to the right works best for finding subjects in the blog.
Interesting! I've always presumed cutting edge developments originate in the racing world, then trickle down to cycle tourists. Yet in this case the parallelogram rear derailleur trickled up instead. Illustrates the value of keeping our minds open to all sources!
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