The Shimano SM-EW90-B is a compact, black plastic junction box engineered for Shimano’s Di2 electronic shifting systems. It features five SD50 E-Tube ports, allowing riders to connect up to two pairs of Di2 shifters (such as main shifters and remote sprint or time trial shifters) along with the main downtube junction box, all while keeping wiring tidy below the handlebar.

This unit is ideal for cyclists seeking flexible cockpit setups—whether for road racing, gravel, or time trial bikes—where multiple shifting positions enhance control and rider ergonomics. The SM-EW90-B is compatible with Shimano Di2-equipped bikes that use the new internal batteries, offering both a charging port and an LED battery charge level indicator for convenient maintenance.

Installation is straightforward: the junction box mounts directly under the handlebar or stem, routing cables internally or externally for clean integration. It supports a broad range of Di2 shifters and remote controls, making it a practical upgrade for riders wanting to expand shifting options or needing to manage complex electronic setups. Compatibility checks ensure seamless operation across the bike’s Di2 system, and all components should run the same firmware version. The SM-EW90-B is lightweight (about 12 g), robust, and designed to withstand the rigors of both indoor and outdoor use. Its main strengths include its port density for advanced setups and the convenience of an integrated charging port.