The Shimano Alfine Di2 MU-UR500 Motor Unit is the electronic actuator at the heart of Shimano's Di2 internal gear hub shifting system. When you press a Di2 shifter button, this compact unit receives the electronic signal and precisely moves the hub's internal mechanism to execute a smooth, reliable gear change — automatically and instantly. It's the component that brings electronic intelligence to internally geared city and touring bikes, letting you shift without cables, housing, or manual adjustment.

Highlights

• Fully automatic shifting: Responds instantly to Di2 electronic signals for seamless, effort-free gear changes on internal hub drivetrains.
• Compact and lightweight design: 35% smaller than the predecessor MU-S705, making installation neater with less impact on overall weight.
• Quiet operation: Engineered for low noise output, keeping the riding experience calm and unobtrusive in urban environments.
• E-Tube connectivity: Connects via the Shimano E-Tube system (compatible with EW-SD50 cable) for reliable electronic communication with shifters and junction boxes.
• Firmware upgradeable: Supports Shimano E-Tube Project software for future firmware updates and system customisation.

How It Works

The MU-UR500 mounts directly to the Alfine Di2 internal gear hub and serves as the electromechanical actuator. Unlike a conventional mechanical shifter that relies on cable tension, the MU-UR500 drives gear selection electronically — translating button presses at the handlebar into precise internal hub movements. The result is consistent, maintenance-friendly shifting with no cable stretch or housing wear to manage.

Compatibility & Fit

The MU-UR500B is the 8-speed variant, designed for use with the Shimano Alfine SG-S7051 Di2 8-speed internal gear hub and compatible NEXUS Di2 internal hubs. It is compatible with the full range of existing NEXUS Di2 and ALFINE Di2 gear hubs. E-Tube connection is via EW-SD50 cable (1 E-Tube port). Verify hub and Di2 system compatibility before ordering.