Shimano officially announced Dura-Ace Di2, a technologically advanced, electronic shifting option for the all new 7900 series Dura-Ace. Comprised of Dual Control type shift / brake levers, front derailleur, rear derailleur, and a battery pack, the new Dura-Ace Di2 7970 components provide precision electronic performance and integrate seamlessly with components from the 7900 series Dura-Ace group while adding only 68 grams to the entire group.
Electrically actuated shifting significantly eliminates issues associated with cable friction and contamination because the derailleurs respond to electrical impulses that are delivered in fractions of a second. The shifters are now merely switches which also allows for creative placement of optional remote shifters while also reducing the weight and profile of the main shift units. Derailleur movement is precisely controlled through computer automated movement and servo motors creating perfectly synchronized and calibrated shifts every time.
ST-7970 Dura-Ace Di2 Dual Control Levers
By using unidirectional carbon fiber brake lever blades and eliminating all of the mechanical shifter parts, the new Dual Control lever weight is reduced by over 155g over the mechanical version. The ergonomics are slimmed down and further refined for a comfortable grip.
The wiring harness for the shifters is designed to accept the all new FlightDeck computer (SC-7900) featuring heart rate, altitude, grade, cadence, estimated caloric consumption, gear position, and battery life all directly downloadable data via a wireless connection.
* Unidirectional carbon fiber lever blades reduce weight without loss of durability
* Shifting positions mimic Dual Control with the ease of an electric switch
* Titanium clamp and fixing bolt
* Enhanced perch shape is more comfortable over longer distances
* Integrated reach adjuster provides a custom fit for even smaller hands
* Shift impulses transmitted in fractions of a second
* Revised brake cable pivot location provides better braking modulation
* Optional satellite shifter
* Wiring harness is FlightDeck ready
RD-7970 Dura-Ace Di2 Rear Derailleur
Like the 7900 mechanical derailleur, the 7970 has a new carbon fiber rear pulley cage and the new design is compatible with wider range cogsets, accommodating up to a 27 tooth cog. The differences are the fact that the unit is now driven by a servo motor instead of a cable and spring, so shifts are identical and precise every time as the computer control unit analyzes each shift.
The derailleur has a built in mechanism that will allow the body to move inward under impact to reduce the potential for damage in the case of a crash. Cycling through the shifting a couple of times allows the shifter and rear derailleur to automatically re-synchronize.
* Carbon fiber rear pulley cage for lighter weight without loss of durability
* New geometry allows for use of 27 tooth max cog
* Servo saving feature allows derailleur body to move inward on impact to reduce or eliminate damage to the component and servo motor
FD-7970 Dura-Ace Di2 Front Derailleur
The front derailleur is the “brains” of the system. The integrated ultra-compact CPU not only ensures that shifting is perfect for both the front and rear derailleurs individually, but also by monitoring the position of each, creates a front derailleur that tracks the chain and requires zero manual trim without sacrificing any shifting speed. The front derailleur logic also performs the inward shift from the big chainring in two parts to eliminate chain drop, with both actions measured in fractions of a second.
* Integrated CPU monitors both front and rear shifting for precise and consistent derailleur alignment
* Computer integration allows the front derailleur to track the chain eliminating the need for manual trim and also eliminates chain drop when shifting inward from the big ring.
SM-BTR1 Dura-Ace Di2 Battery Pack
The 7.4V, high performance Lithium Ion battery is designed to deliver reliable, long life even in the worst conditions. In conditions requiring consistent and frequent shifting, the battery is capable of 1000 kilometers of use.
The battery is rechargeable and comes with a mount that easily adapts to most bikes. Lithium Ion technology is lighter, more compact and better performing than other power sources, making it a clear choice for Di2.
* High performance Lithium Ion composition
* Rechargeable (1.5 hours for full charge)
* Mounting bracket to easily adapt to most bikes
* Approximately 1000K of heavy use between charges
SC-7900 Flight Deck Cycle Computer
* Gear indicator with virtual cadence
* Heart rate monitor
* Estimated caloric consumption
* Altitude & inclination
* Battery life indicator
* Wireless PC connection
Dura-Ace Di2 redefines the highest level of component performance and solidifies the brand as the benchmark for professional cyclists and road cycling enthusiasts alike. Dura Ace Di2 will be available January 2009.