Shimano 105 Di2 RD-R7150 12-Speed Rear Derailleur

Name: Shimano 105 Di2 RD-R7150 12-Speed Rear Derailleur
Brand: Shimano
SKU: IRDR7150E
Price: 243.00 NZD
Availability: InStock

$243.00 NZD

Taxes included. Shipping calculated at checkout.

The Shimano 105 Di2 Rear Derailleur delivers fast, precise 12-speed electronic shifting, integrated system control and wide-range 36T cassette compatibility, making it a high-value road bike upgrade for training, commuting and endurance riding.

Shimano 105 Di2 Rear Derailleur Features

Fast electronic Shimano Di2 shifting with a high-performance motor and optimised linkage.
Compatible with Shimano 12-speed road cassettes featuring a 34T or 36T largest sprocket.
Central Di2 control hub integrates wireless reception, charging, pairing, adjustment controls and status LEDs.
Low-profile Shimano Shadow RD construction reduces exposure to knocks and accidental contact.
Bluetooth and ANT connectivity supports drivetrain setup, firmware updates and compatible bike computer displays

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Core specifications

Product type: Electronic road bike rear derailleur
Series: Shimano 105 R7100 Di2
Rear speeds: 12
Intended drivetrain: Shimano 2x12-speed road Di2
Derailleur construction: Shimano Shadow RD
Maximum largest sprocket: 36T
Minimum largest sprocket: 34T
Compatible smallest sprocket: 11T
Maximum front chainring difference: 16T
Total drivetrain capacity: 41T
Pulley size: 11 teeth
Pulley bearings: Bushings rather than sealed cartridge bearings
Fluoric-coated link bushings: Four
Mounting: Conventional road derailleur attachment or compatible Shimano direct mount
Electrical standard: Shimano SD300
SD300 ports: One
SD50 ports: None
Charging cable: Shimano EW-EC300
Claimed average weight: 302g
Colour: Shimano series black
Clutch: No
Firmware updates: Supported through Shimano E-TUBE PROJECT Cyclist
Wireless communication: Bluetooth Low Energy and Shimano private ANT communication
Status indicator: Integrated LED
Adjustment control: Integrated function button
Charging port: Integrated into the rear derailleur body [productinf...himano.com], [georgesbik...hop.com.au]

Compatible cassette combinations

The Shimano 105 Di2 Rear Derailleur is officially designed around road cassettes with an 11T smallest sprocket and either a 34T or 36T largest sprocket.

Common compatible combinations include:

Shimano 105 11-34T 12-speed cassette
Shimano 105 11-36T 12-speed cassette
Compatible Shimano 12-speed road cassettes that remain within the specified 11T top sprocket, 34T to 36T low sprocket and 41T total capacity

Required supporting components

Compatible Shimano 12-speed Di2 road shift controls
Shimano BT-DN300 central battery
Shimano EW-SD300 electrical wire
Shimano EW-EC300 charging cable
Compatible Shimano 12-speed road cassette
Shimano 12-speed HG road chain
Compatible Shimano Di2 front derailleur for a complete 2x system
Suitable road derailleur hanger
E-TUBE PROJECT Cyclist app for configuration and firmware management

The derailleur does not contain the main rechargeable battery. The BT-DN300 battery is normally installed inside the frame or seatpost and connected to the front and rear derailleurs with SD300 wiring. The integrated charging port on the rear derailleur allows this shared battery to be charged without removing it from the bicycle.

Shimano Di2 electronic shifting

A high-performance electric motor moves the chain accurately across the cassette without relying on a mechanical shift cable. This removes cable stretch, housing friction and gradual cable contamination from the shifting process. Once the hanger, limit settings and indexing are correctly adjusted, shift performance remains consistent through changing weather and extended use.

Semi-wireless system architecture

Compatible Di2 controls send shift commands wirelessly to the rear derailleur. The rear derailleur is wired to the shared internal battery, while the front derailleur also receives power from that battery through a separate SD300 connection.

This architecture provides a clean handlebar area without placing a separate rechargeable battery on each derailleur. It also permits the entire drivetrain to be charged from one accessible port.

Central system integration

The Shimano 105 Di2 Rear Derailleur combines several functions previously distributed between separate Di2 components. Its compact housing incorporates:

Wireless receiver
Charging port
System status LED
Battery-level indicator
Pairing control
Adjustment-mode switch
Bluetooth communication
Compatible ANT drivetrain communication

This consolidation simplifies installation and removes the external junction boxes used by earlier Di2 generations.

Shimano Shadow RD

Shimano Shadow RD positions the derailleur closer to the bicycle and reduces its outward profile. This helps protect it from accidental contact, transport damage and minor falls while providing a cleaner silhouette at the rear wheel.

The Shimano 105 Di2 Rear Derailleur is not equipped with the stabilising clutch found on Shimano GRX and mountain bike derailleurs. It is principally intended for paved-road riding rather than rough gravel or technical trails.

E-TUBE PROJECT integration

The Shimano E-TUBE PROJECT Cyclist app allows compatible users and bicycle mechanics to:

Install firmware updates
Select manual or synchronised shifting behaviour
Adjust multi-shift speed
Review battery status
Complete rear shifting micro-adjustment
Configure button functions
Pair compatible devices

Official drivetrain limits

Rear speeds: 12
Smallest cassette sprocket: 11T
Largest cassette sprocket: 34T to 36T
Maximum front chainring difference: 16T
Total capacity: 41T
Pulley diameter specification: 11 teeth per pulley
Intended drivetrain: 2x12-speed Shimano road Di2

Frame fit

The Shimano 105 Di2 Rear Derailleur fits a conventional Shimano road derailleur hanger using its supplied bracket arrangement. It can also support Shimano’s direct-mount format when used with the appropriate hanger and bracket configuration.

Shimano direct mount should not be confused with the SRAM Full Mount or UDH derailleur system. Most Australian road bikes use a standard replaceable derailleur hanger, so the standard mounting arrangement will be appropriate for the majority of installations.

Cassette fit

The derailleur is optimised for a 34T or 36T largest sprocket. It is not officially specified for smaller traditional road cassettes such as 11-28T, nor for wide-range gravel or mountain bike cassettes larger than 36T.

Correct chain length, hanger alignment and B-screw adjustment remain important. Electronic indexing cannot compensate for a bent hanger, worn cassette, incorrectly sized chain or damaged derailleur cage.

Compatibility notes

Designed for Shimano 12-speed road Di2 systems
Not a direct replacement for an 11-speed Di2 rear derailleur
Not compatible with older Shimano SD50 wiring
Not intended as a standalone upgrade to a mechanical Shimano groupset
Requires the appropriate BT-DN300 battery and SD300 wiring
Requires compatible 12-speed Shimano road chain and cassette
Does not provide a clutch for demanding gravel or trail use

The Shimano 105 Di2 Rear Derailleur is best suited to road cyclists who want accurate electronic shifting without the premium price attached to Ultegra or Dura-Ace. It performs particularly well on road bikes, endurance bikes, commuter builds.

Product care

Clean the derailleur regularly using a soft brush, damp cloth and bicycle-safe cleaner.
Remove abrasive road grit from the pulleys, cage and linkage after wet or dusty rides.
Avoid spraying high-pressure water directly at the motor housing, charging port, pivots or SD300 connection.
Keep the charging-port cover clean and fully closed before riding.
Inspect the EW-SD300 wire for abrasion, pinching and secure engagement.
Check the derailleur hanger after a fall, transport incident or unexplained decline in shifting quality.
Measure chain wear regularly and replace the chain before it accelerates wear to the cassette and pulleys.
Check both derailleur pulleys for contamination, wear and free rotation.
Charge the drivetrain before major events or extended rides.
Install firmware updates through Shimano E-TUBE PROJECT Cyclist when appropriate.
Use the Shimano TL-EW300 wiring tool when connecting or disconnecting SD300 wires.
Have significant indexing faults or impact damage assessed by an experienced Shimano Di2 bike mechanic.

Micro-adjustment should only be completed after confirming that the derailleur hanger is straight, the cassette is correctly installed and the chain is in serviceable condition. Repeated electronic adjustment will not correct a mechanically misaligned drivetrain.

Warranty

Shimano Australia provides a two-year limited warranty for eligible Shimano bicycle components purchased new in Australia by the original retail purchaser.

BikeRadar’s launch analysis similarly presented Shimano 105 Di2 as an important step in making semi-wireless 12-speed electronic road shifting more accessible. The publication highlighted the similarity between its operating principles and Shimano’s premium groupsets, with weight and material differences accounting for much of the product hierarchy rather than a fundamental loss of electronic functionality.

Shimano Ultegra Di2 Rear Derailleur

The Ultegra Di2 alternative is lighter and uses more premium construction with upgraded pulley hardware. It supports Shimano’s wider road cassette range and is a better match for lightweight race bikes. Its shifting feel is exceptionally refined, but the performance difference is relatively small compared with the additional cost.

The Shimano 105 Di2 Rear Derailleur is the better-value option for training, endurance events, commuting and amateur racing. Ultegra is more appropriate when reducing weight and achieving a consistent premium groupset specification are priorities.

Shimano Dura-Ace Di2 Rear Derailleur

Dura-Ace is Shimano’s flagship racing option, delivering the lowest weight, premium materials and top-level finishing. It is suited to competition bicycles where every gram matters.

The Shimano 105 Di2 Rear Derailleur is considerably heavier, but it offers much of the same functional electronic experience at a significantly lower replacement cost. Dura-Ace also has a more race-focused cassette capacity, while the 105 component’s 36T compatibility is advantageous for steep recreational riding.

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