How SRAM's wireless gear system turns road bikes into micro-networks

The introduction of electronics into the human-powered sport of cycling has been both embraced and targeted for extinction by the sport's establishment.

Cycling's current leading villains are hidden buttons on bikes equipped with wireless connections to operate tiny electric motors hidden in cranks and wheels. Both the French government and the International Cycling Union are making a significant show of force against what has come to be known as electronic doping.

On a recent Tour de France finish line at a ski resort, about 10 bikes were tagged and whisked into a brown tent. Inside it, officers from a branch of the gendarmerie (French military police) that deals with doping, and race referees, ran the bikes through an airport-style X-ray machine.

Out on the road during several stages this year, cycling union referees have aimed thermal imaging cameras from the French government at bikes, looking for telltale heat patterns created by motors.

And every morning, referees wander around the start area with magnetic resonance imaging (MRI) devices attached to tablet computers, which, the cycling union has said, can detect race-boosting electronics stuffed inside frames.

We're asking the riders to manage two shifters instead of four.

Brad Menna

The cycling union declined to comment about its findings during the opening week of the Tour de France. The absence of any penalties suggests that nobody has had the nerve to test out the effectiveness of the inspectors.

No one in the sport, however, has any complaints about the electronic devices that now track the riders during the race, generate vast amounts of data on their performances and, for the first time this year, provide live television images from their bikes.

Shifting gears

SRAM, a bicycle parts maker based in Chicago, has added another one to the mix this year. Shimano, the bike industry giant from Japan, and Campagnolo, the venerable Italian company, have both long offered cyclists electronic gear-shifting systems. But SRAM's new offering, Red eTap, effectively turns bikes into micro-networks that allow shifting that is both wireless and electronic.

Getting there proved more complex than the company expected – it was a more-than-five-year process. Now the company has to convince cyclists that having something like a miniature Wi-Fi network on their bikes to change gears is a useful innovation.


Scott McLaughlin, SRAM's drivetrain director, acknowledges that he was not all that keen about any kind of electronic shifting when the company first turned its mind to it.

"I've been bike racing for 30 years, and when we started talking about this project, I wasn't the least bit interested or excited about the product," he says. "But I've become a believer and hope never to ride a mechanical bike again."

Electric dreams

As is the case in the general marketplace, Shimano's products dominate the Tour de France. Of the 22 teams at the race, 17 shift their gears with its Dura Ace derailleurs. Only two teams - AG2R from France and Katusha from Russia - use Red eTap.

After years of sponsorship, Shimano's first Tour de France victory did not come until 1999. (Although, like all of Lance Armstrong's wins, it has since been erased from the official records.)

The company introduced a series of innovations. First it moved shifting from tiny levers on the bike frame to spring-loaded devices inside the brake levers, allowing riders to change gears and keep their hands on the handlebars. Then, in 2009, it brought out the first commercially successful electronic shifting system, Dura Ace Di2.

As a latecomer to electronics, SRAM needed something to distinguish itself. One obvious weakness with both Shimano's and Campagnolo's systems was the wires connecting the shift levers, the derailleurs and a battery. They must be threaded through tiny internal channels on carbon fibre frames. For bike manufacturers, the often tricky process increased assembly times and, thus, cost.

Dark past of wireless

But using wireless for shifting has a dark past. In 1999, Mavic, a prominent wheelmaker based in France, introduced a wireless, electronic gear-changing system known as Mektronic. It was widely seen as a spectacular technology and marketing failure.

Despite wireless advances since then, SRAM quickly discovered that off-the-shelf wireless systems were not up to the job. With Bluetooth, for example, there was too great a time lag. Other systems strained batteries.

As a result, SRAM was left to come up with a wireless system of its own.

"It was a big, big job, and it took a while," says Ron Ritzler, another drivetrain executive at the company.

While SRAM's engineers worked on that and other puzzles, like cutting power use to improve battery life and waterproofing, designers at the company reconsidered how shifting might work once freed from physical connections.

Divide and conquer

Brian Jordan, the company's advanced development manager, said that led them to meet with a company that designs cockpits for fighter jets.

On a bike used in road stages at the Tour, both the Shimano and Campagnolo systems mimic their mechanical counterparts. The left lever shifts the derailleur at the crank, and the right lever shifts the rear derailleur across the 11 sprockets on the hub. Both levers are split in two to control each of the directions the chain can be shifted.

SRAM's novelty was to make the right-hand lever shift the rear derailleur only to bigger sprockets – giving riders an easier-to-pedal gear. Most of the time, the left lever also works on the rear derailleur, handling shifts to smaller sprockets and thus making for a more difficult to pedal gear ratio. The front derailleur shifts by moving both levers simultaneously.

"We're asking the riders to manage two shifters instead of four," said Brad Menna, SRAM's manager for road bike products.

In a sense, that's a return to the old days of two small levers mounted on the frame. But in the conservative world of road cycling, breaking the left-right divide for controlling the two derailleurs verges on heresy.

New York Times