Shimano 105 R7170 Di2 12 Speed Shift/Disc Brake Set - Rear 105 R7100 / R7150 It's A New Day For the 40th anniversary since its launch in 1982, the 105 series gets its ultimate upgrade with Shimano's electronic Di2 shifting technology. Maintaining the series-typical price level, the precise shifting function, precisely tuned ratios and a reliable braking system thus become accessible to an even wider circle of road cyclists. Because in the tradition of its predecessors, the current 105 is also equipped with the top technologies such as the wireless cockpit and first-class features from the state-of-the-art Dura Ace and Ultegra series to enable their riders to discover the road anew, every single day. Shimano 105 Di2 RD-R7170 STI brake/shift lever As with the current STI levers of the Dura Ace and Ultegra series, Shimano has again collaborated with professional riders in the development of the electronic 2x12-speed control units of the 105 series. Not only that also a Wireless system has found its way to provide a tidy and wonderfully minimalist cockpit, also the ergonomics was extensively tweaked. Characteristic of the revised aesthetics and aerodynamics are above all the raised lever hoods, which prevent fatigue regardless of the hand position and ensure first-class comfort. But also on the technical side, the compact dual control levers know how to convince. While the reach adjustment mechanism allows adaptation to different hand sizes or riding styles and thus promises more control in racing, the button functions that can be individually assigned via E-Tube app benefit an essential task of the control units: the shifting performance. A self-developed circuit ensures reliable and fast signal transmission, which not only enables more precise and direct shifting processes in manual mode, but also more intuitive ones. Athletes who want to devote themselves fully to racing can also leave the gear changes completely or at least partially to the Synchronized Shifting technology. The switch to electronic Di2 shifting naturally also offers decisive advantages in terms of ease of maintenance. With a battery life of at least 3 years, no rider needs to worry about powering the wireless shift/brake levers either. Speaking of brakes, with an extended control range, also the smooth Servowave brake levers experienced a significant upgrade in terms of dosage and deceleration performance. Ports: 1x EW-SD300 Shimano 105 BR-R7170 disc brake caliper Thanks to the natural deceleration feel of the hydraulic Shimano BR-R7170 brakes, athletes can test their limits even further. While their flat profile makes the Flatmount disc brake calipers ideal for use on road bikes, a 10 % larger pad spacing compared to the previous model reduces the risk of unwanted brake friction and grinding brake discs. This reduces overall noise during deceleration, but without compromising braking performance. On the contrary, the BR-R7170 calipers not only grip quickly, but also reliably. To keep the maintenance effort as low as possible, the proven One-Way-Bleeding system is used once again, combined with a simplified bleeding process, which makes it unnecessary to first remove the brake caliper from the frame. J-Kit (Easy Hose Joint System) / At brake systems with J-Kit hose joint the brake lever features an integrated olive which makes an easy brake hose installation and removal possible. Material: STI lever: aluminum (anodized), glass fiber reinforced plastic (GFRP) brake caliper: aluminum (painted) pistons: resin Compatibility: front derailleur: FD-R7150 , FD-R9250, FD-R8150 rear derailleur: RD-R7150 , RD-R9250, RD-R8150 sub brake lever: BL-RX812 brake disc rotor: SM-RT70, SM-RT64 brake pads: K05S-RX Resin, L05A-RF Resin, L04C-MF Metal (manufacturer recommendations, listing not final) Weight (manufacturer's specification): approx. 423 g (STI lever, pair) approx. 123 g (brake caliper).