Shimano SM-JC41 Di2 Internal Frame Junction Box 4-Port

The Shimano SM-JC41 Di2 Junction Box is an internal 4-port junction designed for Shimano Di2 electronic drivetrains, acting as a central connection point for wiring inside the frame to keep setups clean and protected. It allows multiple components—such as shifters, battery, and derailleurs—to communicate seamlessly, ensuring reliable signal transmission and consistent shifting performance. Designed to be hidden within the frame, it supports a streamlined build while maintaining easy serviceability for riders running wired Di2 systems.