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Shimano Dura Ace Di2 7970

Electronic Dura Ace

The following is a NY Times review of the new DA Electronic Group:

February 14, 2009

Cycling Enters the Electronic Age With a New Gear-Shifting System
The bicycle, one of the world’s most resolutely human-powered machines, will join the long list of devices that have switched from the manual to the electronic when a new gear system makes its debut this weekend at the Tour of California.
Although the battery-powered derailleur by Shimano promises to bring ease and accuracy to changing gears by enabling riders to shift with a light touch to two electronic switches, traditionalists worry that it may erode the basic tenets of the sport.
“People choose bicycles precisely because a bicycle’s motion requires only human effort, and nothing could be more simple, independent and autonomous,” Raymond Henry, a cycling historian in St. Etienne, France, wrote in an e-mail message. “Any source of external energy, however weak, runs counter to this philosophy.”
Whether the gear system becomes the next iPod and redefines bicycle technology or ends up as the sport’s version of the eight-track tape will hinge on a number of factors, the most obvious being performance, reliability and cost.
Two earlier attempts at electronic gear changing by a French company, Mavic, often malfunctioned in rain. Another company, Campagnolo, has delayed bringing its version to market because of the economic downturn.
Shimano’s version, known as the Dura-Ace Di2 7970, is being used by three professional teams competing in California: Columbia High Road, Garmin Slipstream and Rabobank. About 10 riders will race with the system even though they have used it on only one or two training rides after receiving them late this week.
Bob Stapleton, the owner and general manager of Columbia, said many of his riders had doubts about using bicycles that could literally run out of power. The Di2 system has no manual override if its battery goes dead. That event can be an irritation or a disaster, depending on the terrain and what gear ratio the bike is stuck in. Shimano estimates the battery will last for about 1,000 miles per charge.
“Their careers can be made on the results from one race,” Stapleton said of his riders. “So they prize reliability over everything.”
Stapleton, an experienced amateur cyclist, has used the Di2 system extensively and is a convert.

“I think every high-end bike within three years will have this, maybe sooner,” he said, adding that the system also eliminates much of the maintenance required by mechanical systems.
A full set of components with electronic gears will cost about $1,250 more than the newest mechanical version, which sells for about $2,750. Upgrading an existing Shimano system is expected to cost about $2,200. The system will fit onto nearly all racing bicycles.
Later this year, Giant, the largest bicycle manufacturer in the world, will offer a bike designed to use only electronic parts for about $14,000, which includes the cost of Di2. If consumers fancy the device, it will likely follow the pattern of other new electronics and drop significantly in price over time.
Electronic gear-shifting technology has spent a long time in development. Prototypes of Mavic’s first system, the Zap, made a cameo appearance at the 1992 Tour de France and the company introduced its second attempt, the Mektronic, in 1999.
For much of this decade, both Shimano, which dominates bicycle parts the way Microsoft dominates computer software, and its venerable Italian competitor Campagnolo occasionally tested prototype systems on the bikes of pro riders. More often than not, the prototypes were devoid of trademarks, presumably to limit embarrassment if results proved as unfortunate as the Zap.
The Campagnolo and Shimano systems share the basic design of current mechanical derailleurs. That is, a parallelogram that moves the chain back and forth and, in the rear, two spring-loaded wheels to keep the chain taut.
Two paddle-shaped electronic switches that sit behind the brake lever allow riders to shift gears. Tapping either paddle lightly in Di2 sends an electronic signal through a wire to a small motor inside the derailleur, moving the body and thus the chain by turning a worm gear. Even Devin Walton, a spokesman for Shimano, acknowledges that when it comes to the rear derailleur, there is little or no difference in shifting between the electronic and comparable mechanical offerings from the company.
The gains are more obvious, however, with the front derailleur, which moves the chain between the two large, toothed rings on the bicycle’s crank.
That is partly because the electronic front derailleur is able to make constant readjustments to reflect changes in the chain’s position caused by shifting with the more frequently used rear derailleur. That allows the electronic front derailleur to use a more efficient shifting mechanism, one that would drive riders to the point of distraction with fiddly readjustments on a mechanical system.
Campagnolo has faith in its electronic system and is waiting for an upturn in the economy before launching. “We’ve got extremely positive feedbacks concerning shifting quickness, precision and user friendliness,” Lerrj Piazza, a spokesman for Campagnolo, said.
Because cycling teams rely on sponsorship from companies like Shimano for their financial survival, several riders were reluctant to discuss their concerns about the system, which range from the prospect of battery failures to difficulty shifting gears using the small and very sensitive paddles while wearing gloves. But after a couple of training rides, George Hincapie of Columbia said he agreed with his team owner, Stapleton, about its merits.
“The shifting is amazing,” he said. “I was very impressed as soon as I tried it.”
The action of the electronic system is so effortless that, compared with mechanical levers, it leaves users feeling almost disconnected from the bike.
After trying the system, Jonathan Vaughters, the chief executive of Garmin Slipstream, anticipates that initially it will be most widely used on special bicycles used for time trials, races against the stopwatch, and triathlons. Vaughters, a former professional rider, believes that most of the two-second margin by which Chris Boardman won the opening time trial of the 1997 Tour de France was owed to his electronic Mavic derailleur. The device, which worked for that race’s 7.3 kilometers, allowed Boardman to maintain his aerodynamic position even while shifting.
If Di2 does prove to be reliable and is a success in the market, do not expect an automatic transmission next. Walton says that such a system, at least for racing bikes, would need to analyze a rider’s physical state and well as read his mind.
“There’s no way for the system to know when you’re about to sprint,” Walton said. “When you’re in competition, you have to be in control.”