For visually impaired users: Browse the streamlined version of our website.

Shimano EW-SD50 Di2 External B Junction Box

Low Price: $28.99
Add To Cart Add to Wish List
In Stock Online!
FREE Shipping Eligible!
This item is eligible for Super Saver Shipping Learn More
This item earns up to 29 VIP Reward Points Learn More

This is the Shimano Ultegra Di2 External Junction Box for connecting the two derailleurs, battery, and cockpit controls in a Shimano Di2 electronic shifting system. This junction works with all Di2 with e-tube wired system components as long as firmware is updated to same version between all the connected components.


  • Mounts underneath the bottom bracket shell
  • Frame Junction Box connects via SD50 E-tube wires to four different points: front derailleur, rear deailleur, cockpit junction box and battery mount
  • Use Di2 system checker to update component firmware from
  • All Di2 components on the bicycle require the same firmware version. Using Di2 components with different firmware versions may cause malfunctions

    Sizing     Sizing

This product was added to our catalog on March 7, 2018