Bike porn

Actually derialleurs had been around for a long time, French cyclo-tourists had been experimenting with variable gears since the start of the century.
**Joaney Panel **adapted a 1908 design of the French Cycling guru Velocio to make the first widely available derailleur in 1912

http://www.flickr.com/photos/cycleczar/3818496648/

http://www.disraeligears.co.uk/Site/Chemineau_derailleurs.html

Variable gears were not allowed in Le Tour for many years. Also pro racers were reluctant to use them because of the belief in the importance of chain-line and the need for bomb proof components -most races were endurance events -an average stage in the Tour then was in the high 200s miles on dirt roads.
So, although aluminium cranks were available from the late 30's, in the early 50's the winning bikes at the Tour/Giro still had cottered steel cranks.

-Just a little history, if any of you are interested in the evolution of bike design The Dancing Chain by Frank Berto is the book

Trés interessant, merci.