1930s and 1940s Derailleur Systems
I am deeply grateful to Jeff Groman for the photos below from his cycle museum: www.classiccycleus.com
Because of era's bad roads, gear changing systems in the 1930s and '40s had to be both simple and bulletproof. The downside of these mechanisms was that they required a very high level of skill to make them work.
Gino Bartali wears the leader's Pink Jersey in the 1936 Giro d'Italia while riding a Legnano bicycle equipped with the Vittoria Margherita gear system. Riders wore goggles to protect their eyes from dust, mud and rocks thrown up from the era's unpaved roads.
Before derailleurs came into use racers had double-sided rear hubs with up to two cogs on each side of the hub. Changing gears meant stopping and removing the rear wheel and flipping it around to use a different sized cog. Deciding when to perform this operation was an important part of early racing tactics.
The Tour forbade the use of derailleurs until 1937. But unlike the Tour, the Giro d'Italia allowed their use. The Vittoria system made by the Nieddù brothers, Tommaso and Amadeo, was the gear of choice among the Italian pros. Alfredo Binda had used the Vittoria system when he won the world championship in Rome in the fall of 1932. That success resulted in many pros mounting the system on their bikes for the 1933 season.
In the early to mid-1930s a rider probably had three sprockets in the back and one up front. Riding below the chainstay was a pulley wheel which acted as a chain tensioner. Early versions (as in the pictures below) required the rider to reduce the chain tension, pedal backwards and with his gloved hand move the chain to the desired sprocket. Later systems, called the Vittoria Margherita (1935 and on) had a rod-controlled pusher on the chainstay that would move the chain when the rider backpedaled.This is barely visible in the photo above. It was clumsy but it beat getting off the bike then removing, flipping and replacing the rear wheel. Cycle historian Frank Berto noted that the Vittoria derailleur systems were rugged, simple, reliable and the tension wheel rode high enough to give good ground clearance, an important consideration in an era of bad roads. Unlike the some of the more fragile gear changing system on the market at the time, the Vittoria still worked when fouled with mud.
A beautifully restored Stucchi bicycle with the original Vittoria gear system that required the rider to push the chain to the next cog with his hand while backpedaling.
The lever that the rider moved to loosen and tighten the chain tension. It can barely be read, but it is stamped that it was used to win the World Championship. Note the wooden rims and steel cottered crankset.
A detail of the chain tensioner
The bicycles that Coppi and Bartali rode in the 1949 Giro were little changed from their pre-war versions: steel lugged frames, steel cottered cranks and side-pull brakes. But there was one way that they did differ. In the Giro both Coppi and Bartali used Campagnolo's very unusual "Corsa" gear changing system.
Campagnolo had started with his brilliant invention of the quick-release hub. Through the 1930s and '40s he had been producing a small number of beautifully hand-crafted hubs and gear changing systems. His business was so small that he didn't hire his first full-time employee until 1940.
The Corsa system was brilliant in its simplicity and efficiency and mind-boggling in its difficulty to use. It had no energy wasting pulleys. From a short distance a Campagnolo Corsa equipped bike looks almost like a pre-derailleur bike from the Girardengo era. It had two levers on the seat stay. One loosened the quick release and the other was attached to a Vittoria Margherita-type paddle that shifted the chain when the rider pedaled backwards. When the rider loosened the quick release and shifted to a larger cog, the wheel pulled forward from the chain tension. When the rider switched to a smaller cog, gravity let the wheel go back and tighten the chain. Then the rider tightened the quick release while still on the fly. Notches in the dropouts and splines on the hub axle kept the wheel straight. It was simple and bullet-proof, valuable qualities when racing on postwar roads.
A Legnano bicycle equipped with Campagnolo 2-lever "Corsa" gears. Note the lower lever is attached to a chain guide that changes the gears.
A closeup of the system
There are 4 cogs on the freewheel. The notched dropouts can be clearly seen. The top lever actuating the quick release is held in place with a spring, allowing the lever to come loose from the frame to remove the wheel.
A closer view
This bike sports a Gnutti steel cotterless crank that was fitted to a splined steel axle.
A close-up of Campagnolo's single-lever Paris-Roubaix gear system
Simplex, then the best selling derailleur in the world, paid Coppi a bucket load of money to switch to their more modern (two pulleys mounted in a cage that automatically wrapped up the chain slack as it moved the chain across the rear cogs to change gears) system when he rode in the Tour de France.
For the 1949 Tour de France Bartali used the Cervino, an updated version of the old Vittoria system. That was one reason why Coppi and Bartali each needed his own domestiques on the Italian Tour de France team. They used incompatible gear systems and needed their own riders close at hand in case a wheel change was needed.
Bartali ended up buying the Cervino derailleur company. When Campagnolo produced his "Gran Sport" deforming parallelogram derailleur (that's how they still work) in the early 1950s, it set a new standard for reliability combined with shift quality. Nearly always making sure that his bike enjoyed every possible technical advantage, Coppi switched to using the new Campagnolo system.