Keep your Di2 system running seamlessly with the Shimano SM-JC41 Internal Junction Unit, the hidden hub that brings your entire electronic drivetrain together. Designed for internal cable routing, this compact junction box—commonly referred to as “Junction B”—acts as the central connection point for all key components, ensuring fast, reliable communication across your setup. Whether you’re building a clean new bike or upgrading an existing Di2 system, the SM-JC41 keeps everything neatly integrated and performing at its best. Simple, efficient, and essential, it’s the backbone of a smooth-shifting Shimano e-Tube experience.

Key Features:

• Internal Junction “B” unit for Shimano e-Tube Di2 systems
• Connects front derailleur, rear derailleur, battery, and cockpit junction via SD50 wires
• Designed for clean internal cable routing and streamlined builds
• Ensures stable and reliable communication between all Di2 components
• Compact and lightweight design for easy integration into frames

Compatibility Note:
All connected Di2 components must run the same firmware version to ensure optimal performance and prevent system malfunctions.