1950s and Early 60s Derailleur Systems
I am deeply grateful to Jeff Groman for the photos below from his cycle museum: www.classiccycleus.com
Gear changing in the nifty fifities. After the war both Simplex and Huret produced rear derailleurs that used a coiled flat spring to both keep the chain tensioned and help move the chain across the sprockets.
A cable through the center of the spring would pull the jockey/tensioner to the desired cog. These are generally called "plunger-type" derailleurs and were produced in huge numbers. Both lever and cable actuated front derailleurs were made during the 50s.
Louison Bobet won his three Tours de France on Huret derailleurs. Here he is leading on the Aubisque in the 1954 Tour de France. Note he and the rider behind him (Stan Ockers?) have plunger derailleurs.
Let's step back for a minute. Here's a really early Simplex plunger, the 1934 Simplex Champion de France, mounted on a Girardengo bicycle. Note it has a single pulley and the top body pivot is not sprung. Racers used to fear the extra friction of a second derailleur pulley and were willing to sacrifice shifting performance in return for the perceived drag reduction. Later measurements showed the energy loss from the second pulley is negligible.
Peugeot with 2-pulley Simplex 543 rear derailleur
Pictured is the Simplex 543 rear derailleur which came out in 1954. It's still a plunger derailleur, but the pull-chain is hidden inside the derailleur body. The second cable (hard to see) regulates the chain tension.
The Simplex Competition lever-style front derailleur was made in various versions from 1947 to 1970.
Here's an Oscar Egg bike of the 1960s with Simplex derailleurs
In 1961 Simplex produced a first-class parallelogram rear derailleur with a very advanced feature, they sprung the top part of the derailleur body to help tension the chain, which is done on all modern derailleurs. The next year Simplex made one of the worst decisions in the history of the bicycle industry, they decided to make their derailleurs out of plastic (the Peugeot reps always told me to say "Delrin"). They were fragile and nearly all broke. The model on this Oscar Egg was made after 1966 when Simplex added metal side plates to stiffen and reinforce the changer. They were still awful.
The front derailleur that taught bike mechanics how to swear. The Simplex Prestige front derailleur was a dated push-rod design (nearly everyone else used a deforming parallelogram that helped lift the chain during upshifts) and it was plastic and it broke.
Here is an unrestored British Armstrong bike (one of the many brands acquired by Raleigh) from the 1950s with British Cyclo front and rear derailleurs
A close-up of the rear plunger derailleur. British Cyclo sold derailleurs under both "Cyclo" and "Benelux" brands.
Front Cyclo derailleur mounted on Armstrong bike. Sure looks like the lever works a helix to move the cage.
A Louison Bobet bike with the derailleur that changed everything. This bike is mounted with a late 1950s version of the Campagnolo Gran Sport derailleur ensemble. Bobet used Huret through 1955 and switched to Campagnolo in 1956.
Tullio Campagnolo displayed his first version of the Gran Sport at the 1949 Milan bike show. Pulling on the cable deforms the parallelogram and moves the chain across the sprockets while a spring in the lower pivot keeps the chained tensioned. Campagnolo didn't invent the design, he just made it work better than anything else in the world. The Gran Sport was beautiful, tough, reliable and expensive.
The front Campagnolo Gran Sport derailleur used a bellcrank and pushrod to move the cage. It was not as beautiful as the rear, but it was bulletproof.
Here's a Cinelli model "B" with Campagnolo Gran Sport derailleurs
Also a later version of the Campagnolo Gran Sport derailleur. I don't have a good picture of the front changer.
The first mass-produced deforming parallelogram rear derailleur was the Huret Allvit, which made its first appearance in 1958. The Bertin bike above has the first version, before the parallelogram had a protecting cover that was introduced in 1961. A few racers used the Allvit, but its performance couldn't match Campagnolo's.
A close-up on the an early rear Huret Allvit
Huret had not yet begun making parallelogram front changers. This is a pull-cable derailleur that turns a helix to move the cage.
A Raleigh-produced Blue Streak of the early 1960s with Huret Allvit derailleurs.
Here is the rear derailleur Baby Boomers know, the definitive Huret Allvit with the body acting as a protector for the parallelogram. It seemed to come on every bike but Peugeot: Schwinn, Sears, etc. The nuts and bolts needed regular tightening and every now and then the cage seemed to need a good strong twist to straighten it.
French Cyclo continued to make dual-cable, helix-driven rear derailleurs until the early 1960s. They worked well for touring and were usually mounted on a custom braze-on. Pictured is Cyclo rear derailleur on an Alex Singer bike.