The evolution of Shimano's Di2 drivetrain system rolls on. With the release of the R9100 series components, an entirely new hydraulic disc braking system was developed from the STI shift/brake levers all the way down to the rotors. The now legendary Di2 electronic shifting version is here, the ST9170 Di2 STI Levers for hydraulic disc brakes. In the process of developing Dura-Ace R9100, new ergonomic and efficiencies were built into the shifting systems for both mechanical and electronic versions, with options added via the E-Tube project for customizing the shifting set-up of the R9170 Di2 models. Sold as individual levers, left or right, with the specific BR-R9170 complete flat mount brake caliper assembly and SM-BH90 hydraulic hose kit; the buyer still needs to build the E-Tube Di2 wire connection kits required for their bike and desired set-up.

The new Di2 system offers substantial opportunities for direct customization via e-Tube. You can set your carbon shift levers up for Shimano's SyncroShift with two primary options. In fully synchronized shifting, the front derailleur automatically shifts off the placement and shifting of the rear derailleur in combination based on your choices. In semi-syncronization mode, the rider shifts both front and rear normally, but front shifts are augmented by an automated rear shift to moderate the large jumps and pedal lag that can cause. In normal shifting mode you can still program the shift buttons to your preference for which each shift action each lever actuates, or even control compatible computer head unit mode or screen buttons. The E-Tube system allows to do all this from their app on mobile devices or directly through a PC interface. With E-Tube, your system must all be set-up and physically connected, and for the new system you will need to be using a BM-DN100 (external battery mount) or BT-DN110 (built-in battery) and EW-WU101 ANT/BLE wireless connector.

From a physical perspective, the new 9170 hydraulic lever is almost the exact same physical size and shape as it's mechanical brother. Slimmer, with much better ergonomics than ever before, as well as lighter weight, these levers shift a more refined electronic drivetrain with a more positive button response. You still have the capability for integrating with for satellite (sprinter, climber) buttons as well. The new textured hood design provides excellent grip, some mild cushion, and covers the lightweight new plastic composite body housing. The strength and reliability of the housing is what allowed Shimano to engineer the shift action and hydraulic interface down to it's most compact size.

In engineering hydraulic the braking system new BR-R9170 flat mount brake calipers, Shimano wanted to drop weight, increase power, reduce heat build-up and offer more modulated feel through the system to the lever. Each caliper is bit over 250 grams, and very low profile. The lever features free-stroke adjustability for controlled throw and pad contact point. The mono-body caliper is made from aluminum, and has an anodized finish. A ceramic piston drives the caliper action through the pads. Shimano uses a mineral oil based fluid system, which is stable and safe to use, with simple connections and straightforward one-way bleeding via their funnel and fluid process. Shimano has continued their relationship with IceTech for optimal cooling at the rotor/pad/caliper interface. The excellent L02 finned resin pads are included here. The pads provide the quietest, most consistent stopping power and modulation, while the aluminum fins serve to quickly release heat off the pad backer, which is combination of steel and aluminum. You get the pad stiffness and reliability for optimal power, without fade or power loss from overheating. The flat mount standard is becoming ubiquitous on road disc, and many cross disc, frames and forks. Flat mount calipers can also be adapted to post mount systems. The caliper system has a minimal aero footprint, and there is next to zero energy loss from the mounting system, which has allowed frame, fork, and calipers to be stronger and lighter than ever before, with increased performance. Rotors do not come with this kit, but the SM-RT900's are newly designed with IceTech, and are available in 140mm and 160mm sizes for Center Lock disc hub use.

There have been countless reviews and comments about the excellence of Dura-Ace Di2. While other electronic shifting systems have their wondrous features and excellent performance, Di2 is the benchmark that every other shifting system is compared to. Shimano has never rested on their laurels. Witness the E-Tube project, refined lever design, the addition of hydraulic disc brake options, and the most reliable, amazing shifting performance found on a bike. Dura-Ace ST-9170 Di2 STI Levers represent the current highest mountain in the bicycle shifting world, until Shimano vaults it's next system towards the sky. While still a wired system (for several key reasons), Di2 R9170 offers the most impressive combination of shifting performance and hydraulic disc braking cycling has ever seen, with no compromises. Return to Top