The Shimano SM-JC41 Junction Box is a key component of your internally routed Di2 setup. Designed to be hidden within the bike frame, this junction keeps your electronic cabling organized and out of sight for a clean and professional look. Central Connection Hub: This internal junction serves as the central point for all EW-SD50 cables connecting your Di2 system—linking the battery, derailleurs and shift levers. It ensures reliable communication between components, supporting seamless electronic shifting performance. Discreet and Frame-Compatible: Generally positioned inside the seat tube or down tube via the bottom bracket shell, the SM-JC41 remains completely out of view. It’s engineered for use in compatible frames with internal routing and provides a secure, vibration-resistant cable junction. Reliable, Lightweight Performance: Built with precision and trusted Shimano engineering, the SM-JC41 adds minimal weight while delivering essential functionality. Whether upgrading or building a Di2 bike from scratch, it’s an indispensable part of a clean, integrated electronic drivetrain. The SM-JC41 is compatible with a wide range of Di2 series, including Dura-Ace 9070, Ultegra 6870/6770, XTR 9050, XT 8050 and Alfine/Nexus Di2 systems.