These days, modern engineering greets us every time we walk into a local bike shop. Steel tubing is a rare sight compared with the amount of carbon fiber littered about the showroom floor. Bikes utilize hydraulic fluid to activate disc brakes, and modern suspension keeps the tires on the trail. Once clunky mechanical contraptions, derailleurs are now sleek and smooth, some with battery-operated electronics controlling the action. These days you can get a couple dozen gear choices all operated by push buttons. Ever wonder how we arrived at this point? Let’s take a look at the technological progression bicycle derailleurs have made over the decades.
In the beginning, bikes were direct-drive and the only way to get a different gear ratio was to change the size of the wheels. One gear dictated the action, but since the days of the high-wheeler it was obvious that a single gear was less than ideal when faced with big hills or stiff winds.
The earliest multiple-gear bicycles usually employed flip-flop hubs with two or three cogs, or internal gear boxes in the rear hub or the bottom bracket shell. These designs still survive a hundred years later, but have never offered much gear range, and they sure don’t offer the visual fun that external derailleurs give us.
Devices we would recognize as derailleurs really started to appear in the 1930′s. Two popular shifters were the Vittoria Margarita and the Osgear. The Osgear, fully known as the Constrictor Osgear Super Champion was named after the designer Oscar Egg, a famous Swiss-French cyclist from the era. The system was light yet sturdy, and fairly simple to operate. Fitted to the chainstay was a cable operated guide arm that moved the chain right or left across three sprockets. A tension arm near the crankset took up the slack of the chain, and a guide-loop of metal on the tension pulley kept the chain from coming off.
The Vittoria Margerita was a simple and wonderfully designed Italian system from the same era. In order to use the gears, the rider would simply reach down to the lever and move it forward, releasing some of the chain tension. Next, he would back-pedal while pushing on the chain with his right hand. The chain would jump to the next cog over, and then the rider would take the slack back out of the chain by moving the lever rearward again.
Early race organizers worried that wide variations in equipment would skew the results of their events. Single-speed bikes were standard equipment at the Tour de France until 1937, when teams with derailleur systems were allowed to compete.
The Osgear and the Margerita look exotic and still don’t seem that familiar to us. The 1940′s saw the development of derailleurs like those from Simplex, Cyclo and Conloy, and in these systems we see steps toward modern parallelogram designs and controls that use a single shift wire. These devices seem kind of similar to what we have today, but some like the Conloy only had a single pulley, so the total gear difference could only be about six teeth.
In the middle of the last century there were a few missteps as well as leaps forward. One of the goofier ideas was the Trivelox shifter, a derailleur that operated by pulling the freewheel cogs side-to-side under a stationary derailleur. If you can imagine holding a pen over a piece of paper, and writing by moving the paper underneath it, you can understand the limitations of this system. The more gears the Trivelox was asked to shift between, the wider and heavier the rear wheel had to become. Campagnolo also had the bike world take a technological step backward in the late 1940′s with their Cambio Corsa and Paris-Roubaix “suicide shifters”. To use these shifters, you flipped a lever on the seat stay that disconnected the rear wheel (while the bike was moving). The chain was then pushed onto the next cog over with a guide lever, and then the rider would re-tighten the lever to secure the rear wheel. The first version, the Cambio Corsa, had two levers managing this action, and care had to be taken not to lose the wheel out of the dropouts. The later Paris-Roubaix version operated everything with a single lever, and some refinements made this system slightly safer. In both of these systems, long serrated dropouts would keep the rear wheel aligned while the shift was being completed, and rearward force on the wheel would keep the chain tensioned. To anyone who has dropped a chain while shifting their modern bike, it is understandable that these systems required quite a bit of finesse to operate.
Derailleurs that came out in the 1950′s look pretty close to what we see today. Some popular ones, like the Simplex Touriste, had two cables to operate the derailleur. On this derailleur you’ll see a steel pull chain (like on a 3-speed hub) actuating a telescoping pulley arm. A second cable rotates the pulley arm, fine-tuning the chain tension. Derailleur pulleys were still smooth and round in the ’50′s, and didn’t acquire their toothed profiles until the 1960′s. Typically derailleurs like the Simplex could handle 4 or 5 cogs on the back wheel with a 12 tooth spread. Rod-actuated front shifters (reach down the seat tube by your water bottle to operate them) managed chainrings with a range of just a few teeth.
The 1950′s and 60′s brought us Campagnolo’s Gran Sport and Nuovo Record derailleurs. Popular for decades due to their smooth shifts, good durability and light weight, Campagnolo’s beautiful derailleurs have become icons in our sport. It’s easy to know these were hits, as typing “Campy derailleur tattoo” into an image search engine will yield lots of results. Reliable shifting systems like these also meant that road bikes became known as “10 Speed bikes” in popular vernacular during the ’60′s and ’70′s as gear capacity expanded.
Positron indexed shifting came out in the ’70′s. The predecessor to Shimano’s Indexed Shifting (SIS) system of the late eighties, it was the first good “click” shifter. Shimano built the freewheeling mechanism into the crankset, so you could shift gears anytime the bike was moving, not only while you pedaled. This feature made Positron pretty heavy, and use was limited to lower-level utility and sport bikes, not racers.
In the 1980s, Shimano took over the bike world with click shifting and Shimano Total Integration (STI) levers, which moved the shifters up to the handlebars where we could reach them. This idea kept a rider’s hands on the bars, and was a stroke of genius that made road cycling safer, more fun and certainly faster.
Mavic unveiled the first commercially viable electronic derailleur in the ’90′s with their Zap system. The Zap derailleur received signals from battery-powered buttons on the handlebar, but the spinning upper derailleur pulley generated the juice to move the chain. When Zap worked, it worked perfectly. Unfortunately, it wasn’t protected from water and vibration all that well. Today’s electronic shifting builds upon Mavic’s foundation. Shimano’s Di2 and Campagnolo’s EPS derailleurs add automated front derailleurs and give us push button, customizable gear shifts across a wide range of gear ratios.
In the early days, a cyclist was lucky to get more than three gears. The difference between a low and a high gear could mean only a few teeth on a chain ring. Today you can get a bike with 30 “speeds”. We have electronic derailleurs from Japanese and Italian companies as well as”infinite” ratio hub shifting systems and computer-controlled automatic shifting. We take indexed shifting for granted, and demand that controls are placed right at our fingertips. All of this precision is expected today, along with knee-friendly gear ratios spanning dozens of chainring teeth. Times, and gears, change.