The Shimano Ultegra R8170 Di2 Build Kit delivers Dura-Ace-derived electronic shifting and hydraulic disc braking at a price that makes sense. Semi-wireless architecture, 58% faster rear shifts than the previous generation, and servowave braking give you a complete high-performance foundation for any disc road frame build.

Highlights

• 12-speed semi-wireless Di2 electronic shifting — ST-R8170 levers run on coin cells, derailleurs wire to an internal battery
• 58% faster rear shifting and 45% faster front shifting versus previous Ultegra Di2 generation
• BR-R8170 flat-mount hydraulic disc calipers with ServoWave technology for progressive, powerful braking feel
• FC-R8100 crankset with Shimano asymmetrical 4-arm 110 BCD design — available in 52/36T or 50/34T
• CS-R8100 Hyperglide+ cassette eliminates chain shock under load, available in 11-30T or 11-34T
• BT-DN300 internal seatpost battery rated to approximately 1,000 km per charge
• Bluetooth and ANT+ connectivity via Shimano E-Tube app for shifting customisation and firmware updates
• Complete kit — shifters, derailleurs, brakes, crankset, cassette, chain, battery, rotors, wires, and charger included

Semi-Wireless Di2 Architecture

The R8170 Di2 system uses a semi-wireless design where the ST-R8170 brake/shift levers communicate wirelessly to both derailleurs, which in turn connect via wired e-Tube to the BT-DN300 internal battery. The result is a clean cockpit with no wires running through the bars, while the derailleurs benefit from a robust wired power supply. The FD-R8150 front derailleur is 33% smaller in frontal area than its predecessor, and the RD-R8150 rear derailleur integrates a D-Fly wireless transmitter for head unit pairing out of the box.

Hydraulic Braking with ServoWave

The BR-R8170 flat-mount disc calipers pair with the ST-R8170 levers to deliver Shimano's ServoWave actuation — the lever ratio shifts as the pad contacts the rotor, giving a progressive, confident feel that is easy to modulate in all conditions. Rotors are included in the kit (RT-CL800 Centre Lock, 160mm front and 140mm rear or 160mm/160mm depending on kit specification). Brake hoses, fittings, and resin pads with fins are supplied ready for bleed and install.

Drivetrain Performance

The FC-R8100 crankset uses a Shimano asymmetrical 110 BCD 4-arm spider and is available in standard (52/36T) or compact (50/34T) configurations with 165mm, 170mm, 172.5mm, or 175mm crank arm lengths. The CS-R8100 cassette's Hyperglide+ tooth profiles are engineered to eliminate "chain shock" — the abrupt jolt felt when shifting under heavy pedal load — making gear changes smoother at all effort levels. The CN-M8100 12-speed chain is supplied with a reusable Quick-Link connector.

Compatibility & Fit

Designed for flat-mount hydraulic disc road frames. Requires a standard HG11-compatible freehub body (for 11-30T cassette) or an XDR/HG-compatible freehub depending on hub specification — confirm with your wheel manufacturer. Bottom bracket is not included; specify threaded (BSA), press-fit (BB86/BB92), or T47 to suit your frame. A compatible Shimano internal battery mount or seatpost with SD300 port is required for the BT-DN300. Compatible with Shimano Di2 Bluetooth head units and the E-Tube Project app (iOS/Android).