Choosing a gear is also a control problem
Having several gears is one thing. Being able to change between them while riding, without stopping, losing balance or damaging the chain, is another. The shifter is the part that makes that possible, and its history is a history of making a tricky action easy.
Early changers
The first derailleur-equipped bicycles in the early twentieth century were awkward to use. In some systems, the rider had to stop pedaling, reach down to move the chain by hand, or use a lever to push the chain between sprockets while the cranks were backpedaled slightly. Tullio Campagnolo’s rod-operated rear changer of around 1940 was a more elaborate design that required the rider to loosen the rear wheel with a lever, move the wheel to change the chain position and then move the chain. Details of these early systems vary between sources, so they are described here only in general terms.
Hub gears had simpler controls. The best-known early three-speed hub was selected by a small lever near the handlebar, linked to the hub by a short rod or chain. Because the mechanism was enclosed in the hub, the rider needed only to move the lever and ease the pedaling pressure.
Cable-operated derailleurs and friction levers
The postwar parallelogram derailleur worked with a cable pulled by a lever. For a long period, the lever was placed on the frame’s down tube, the sloping tube between the head and the pedals, where it could be reached by the rider’s hand. These levers were called friction shifters because they had no fixed positions: the lever stayed where it was placed by friction in a pivot. The rider moved the lever by feel and listened to the chain to judge when it had settled onto the sprocket.
This took practice, and many experienced riders became very good at it. It also meant that the rider had to take a hand off the handlebar. Variants appeared: stem-mounted levers, which sat on the stem or its extension; bar-end levers, fitted into the ends of drop handlebars; and thumb levers, used on mountain bikes and touring bikes. Each tried to bring the control closer to the hand. Stainless steel cables and plastic-lined housings made the pulling smoother.
Twist grips
Twist-grip shifters, in which part of the handlebar grip rotates to move the cable, became popular on mountain bicycles and many casual bicycles. They allow shifting without releasing the grip but can be accidentally moved. Variants remain in use, particularly on bicycles aimed at casual riding.
Indexed shifting
The major change came in the 1980s with indexed shifting. In an indexed system, the lever has a series of detents, small clicks or stops, each corresponding to a sprocket position. Move the lever one click and the derailleur moves by the right distance. The rider no longer needs to find the position by sound.
Shimano’s Index System (SIS), introduced in the mid-1980s, is generally treated as the point where indexing became mainstream, although other makers had similar ideas. Indexing needed precise cable tension, better housings and a derailleur with predictable motion. Dependable manufacturing made it possible, and it brought gear changing within reach of casual riders as well as experts.
Brake and shift in one
In 1990, Shimano introduced a system that combined the brake lever and the shifter into a single body, usually called STI for “Shimano Total Integration.” A few years later, Campagnolo introduced its own version, called Ergopower, in the early 1990s. In these designs, the same lever that operates the brake can be nudged sideways to shift gears. For road bicycles with drop bars, this meant that the rider no longer needed to reach down to the frame or the bar ends. It affected the shape of the handlebar and the brake lever hood, which was enlarged to contain the mechanism. Mountain bicycles developed their own pairs of thumb and finger shifters at about the same time, mounted next to the brake lever.
Electronic shifting
Around 2009, electronic shifting began to reach production road bicycles. Instead of a cable, the shifter sends an electrical signal to small electric motors that move the derailleur. The advantages include consistent shifts and the ability to adjust settings, while the disadvantages include a battery and higher cost. Wireless versions followed in the 2010s. As with many technologies, adoption has been gradual, and mechanical shifting has remained widespread because it is cheaper and simpler to repair.
Shifters beyond the derailleur
Hub gear controls also changed. The simple lever of early three-speed hubs was joined by twist grips and trigger shifters. Some internal gear hubs now offer many speeds with a single grip or lever. Electronic hub shifting is also available on some bicycles, including certain electric bicycles, which sometimes connect shifting to the motor controller so that the motor can ease off while the gear changes.
What the history shows
The long line from rod changers to electronic controls shows that gears alone were never the whole story. A mechanism that is hard to use is used less, so every step in shifter design made it possible for more riders to use the gears already on the bicycle. Brake levers and shifters are now often designed together, and the handlebar is where the two histories meet.