A practical replacement or build component for anyone organising a compatible Shimano Di2 or STEPS system that uses EW-SD300 wiring and needs four junction ports.
The EW-JC304 is a four-port Di2 Junction [B] designed for Shimano’s newer EW-SD300 electric-wire system. With four SD300-compatible E-TUBE ports and no SD50 ports, it gives you a straightforward way to consolidate wiring between compatible electronic shifting components.
Use it to organise connections between dual-control levers, derailleurs and other parts of an SD300-based Di2 system. Its compact format suits clean internal or external frame routing, while the plug-connection design keeps installation practical. You’ll need the TL-EW300 installation tool, and any unused E-TUBE ports should be sealed with dummy plugs.
For wiring layouts through the EW-JC304, the published maximum total electric-wire length to the dual-control levers is 2,200 mm, while the maximum specified length to either the front or rear derailleur is 1,500 mm. Choose this junction when you need four SD300 ports rather than a two-port connection, and confirm your system uses EW-SD300 wiring before ordering.
Four SD300 E-TUBE ports
Provides four connection points for compatible EW-SD300 electronic wires, giving you more routing flexibility than a two-port junction.
Junction [B] design
Consolidates Di2 wiring inside or outside the frame to help keep the system tidy and easier to organise.
For EW-SD300 systems
Designed for the newer SD300 wiring platform; it has no SD50 ports or SD50 connectors.
Connects key Di2 components
Supports wiring connections between compatible dual-control levers, front derailleur and rear derailleur through the Di2 system.
Compact cable-management solution
Its compact junction format helps create a cleaner installation around the frame and electronic components.
TL-EW300 installation tool
The specified tool helps make fitting and securing the E-TUBE connections straightforward.
Defined wiring limits
Supports up to 2,200 mm total electric-wire length to the dual-control levers, with 1,500 mm maximum specified to each derailleur.
General
Ports and connectors
Electronics and firmware
Weight
Compatibility and wiring
SHIMANO Di2
This junction integrates into a SHIMANO electronic shifting system, allowing multiple EW-SD300 electric wires to be joined in one compact Junction-B component.
E-TUBE SD300
Four SD300-compatible E-TUBE ports provide the connection points required for newer SHIMANO Di2 wiring systems.
Junction [B]
Use the junction to consolidate Di2 wiring inside and outside the frame, helping organise connections between system components.
