After what seems like months of keeping tight lipped whilst the likes of Gerolsteiner?s Fabian Wegmann and numerous other Shimano sponsored Pro Tour teams get kitted out with various prototypes and incarnations, Shimano is finally ready to officially blow the lid on its new Electronic Dura-Ace components, named ?Di2? (Digital Integrated Intelligence).
The new electronic components (branded 7970) will compose of state-of the-art wired STI?s, Front and Rear Derailleurs and a battery pack. The weight of the complete Di2 group (with appropriate 7900 components) will be approximately 113grams lighter than the current 7800 groupset. This weight saving is achieved largely due to omission of mechanical internals and hardware.
The new Dura-Ace Di2 7970 components integrate in both looks and function with components from the upcoming 7900 series Dura-Ace group, while adding only 68 grams to the entire group. Di2 offers a whole new option of low maintenance and 100% controlled shifting for the racers and fast recreational riders amongst us, based upon the tried and tested Shimano SIS indexing system. The technology present in Di2 presents multiple performance advantages that are otherwise unattainable with traditional mechanical setups; the list is long:
– Short shift lever throw
– Fast and precise servo motor derailleur movements
– No adjustment of the derailleurs after initial setup (adjustment and accuracy are monitored with each shift)
– The removal of friction and cable contamination (instead replaced by electrical signals)
– Fewer cables to externally route ? cleaner looking bikes
– The future option for frame manufacturers to internally route the cables
STI Units (ST-7970)
Gone is the sweep of the lever blade, instead replaced by the press of a button. The advantage being the rider can now retain his/her grip on the handlebar and not be disturbed from their assumed race position on the drops. The shift system allows effortless and comfortable shifting also when your hands are frozen from the cold. The operating buttons are positioned in a near identical position to the current finger positions you?d assume for shifting using a Shimano STI unit ? so no re-programming of the brain for the new system, if you?re used to current Shimano set-ups you should be right at home, more-or-less straightaway.
The STI?s have also been provided with a reach adjustment feature to cater for everyone regardless of hand span. The new Di2 STI?s are also compatible with the new FlightDeck computer (SC-7900) that measures important rider data such as heart rate, altitude, cadence, gear position, battery indicator, and more. The FlightDeck works with coded digital wireless signals that prevent interference from other electronic units. The new FlightDeck can also be linked wirelessly to a PC/laptop to upload riding data and map training.
Derailleurs (RD-7970 & FD-7970)
Shimano report that the biggest difference you will notice is just how much quicker and effortlessly smooth shifting between front chainrings is, even under load. The difference in the energy and time (lever action and completed shift) used for front shifts between mechanical and Di2 is truly staggering. The front derailleur also automatically trims; the cage moves automatically in response to the position of the rear derailleur on the cassette to ensure no chain rub, and quiet unobtrusive riding.
The rear derailleur is equally as quick and smooth and with a wide gear ratio capacity (11-27T) will cater for compact setups as well as the traditional road double. The rear derailleur features a carbon pulley plate and titanium B axle for further weight savings.
Dura-Ace Di2 uses a long-life 7.4V Li-Ion battery that is both compact and powerful. Excellent sealing and reliability have been proven through repeated field tests in challenging conditions. The decision to not opt for a wireless system was down to weight. A wireless system would require 3 separate batteries, one for the rear derailleur, one for the front derailleur, and finally, one for the STI?s. The use of a single battery is much more weight efficient and forms a good base for a robust and reliable system.
Time Trial & Triathlon (ST-7971 & SW-7971)
Shimano will also introduce a Dual Control lever that is bar-end mounted for use with time trial and triathlon setups. The carbon brake lever also shares the reach adjustment mechanism of the STI units for a fine-tuned cockpit. These Dual Control Levers are also compatible with the new coded wireless FlightDeck (SC-7900) computer and its computer upload capabilities.
Finally, an electronic satellite switch (SW-7971) will be available that can be mounted onto the end of time trial aero bar extensions. The shift wires can be guided through the bars for optimal aerodynamics and a clean look.
For those who are unsure about the system’s reliability, it has been tested and tweaked by Shimano for nearly five years by Pro Tour riders in all conditions imaginable. Rain, mud, snow, salt, cobble stones, low temperatures, high temperatures and often in multiple combinations. Shimano has assured everyone that Di2 is “100% ready for market”. The first units should be on sale in early 2009.