Ultra-precise 12-speed Di2 Shifting – compact & smartly connected.

The Shimano Ultegra Di2 RD-R8150 rear derailleur is the electronic heart of the 12-speed ULTEGRA R8100 group and combines rear derailleur, junction box, and wireless unit in one compact component. It offers the industry's fastest, most precise shifting function and controls all Di2 functions at the rear – including LED status display, pairing, and adjustment mode.

The uniform cage length simplifies selection: the RD-R8150 covers 12-speed road bike cassettes with up to 34 teeth on the largest cog and offers a total capacity of 39 teeth. With the Auto-Trim function and SHIMANO Synchro-Shift (including semi-synchro support), the system intelligently adjusts gear combinations, reduces cross-chaining, and ensures an always optimally guided chain.

The rear derailleur is wireless-enabled and houses the unit for wireless signal transmission, as well as the central function/pairing button with LED indicator. This allows you to check battery status, pairing, and adjustment mode directly on the rear derailleur. For operation, a Di2 battery (e.g. BT-DN300), corresponding EW-SD300 cables, and the EW-EC300 charging cable are required (not included).

Important note on assembly: The rear derailleur is designed for Direct Mount. The Shimano axle unit for derailleur hangers is not included and must be purchased separately if required. Suitable axle unit:

Shimano number: Y3J198020
EAN: 4550170229375

Highlights:

• 12-speed Di2 Rear Derailleur: electronic shifting precision for modern ULTEGRA R8100 road bike setups.
• Integrated control unit: Wireless function, charging port, function button & LED status display directly in the rear derailleur.
• Synchro-Shift & Auto-Trim: intelligent shifting logic for clean chainline and optimally selected gears.
• One cage for all: uniform cage length for cassettes up to 34 teeth – simplifies component selection.

Technical Data:

• Brand: Shimano
• Group: ULTEGRA
• Series: R8100
• Model: RD-R8150
• Product category: electronic Di2 rear derailleur
• Area of use: Road / Road bike
• Rear gear stages: 12-speed
• Technology: Top Normal
• Recommended chain: HG 12-speed (Shimano Road 12-speed)
• Total capacity: 39 teeth
• Max. largest cog: 34 teeth
• Min. largest cog: 30 teeth
• Max. smallest cog: 11 teeth
• Min. smallest cog: 11 teeth
• Max. front difference: 16 teeth
• Functions: Auto-Trim, Shimano Synchro-Shift, LED status display (battery status, pairing, setup mode)
• Integrated unit: Wireless interface, switch & charging port in the derailleur housing
• Compatibility: Shimano ULTEGRA R8100 12-speed Di2 systems
• Color: dark grey / ULTEGRA-finish

Scope of Delivery:

• 1 x Shimano Ultegra Di2 RD-R8150 Rear Derailleur | 12-speed | electronic
• without axle unit / derailleur hanger
• Note: Workshop packaging (without outer packaging)

Manufacturer Part No.: IRDR8150F | EAN: 4550170240967

The Shimano Ultegra Di2 RD-R8150 is the central shifting and control unit for your 12-speed Di2 road bike – compact, fast, precise, and ready for modern, wirelessly connected road setups.