ms6073 wrote:
That is nice and clean. Since the Di2 shifters each have 3-ports, I would think we could eliminate the 3-port juntion box by using an e-tube wire to connect the left shift lever to the right, then use a long wire from one of the shifters to the 4-port junction at the down tube/bottom bracket. For charging the battery, firmware updates, or troubleshooting, you could use the extra wire from bridging the shifters to connect the 3-port junction inline with the wire that bridges the shifters.
You need the "brain" in the junction A. JC41 will not work here. I used the EW-6770 because it is smaller and ligher than the 3 port although your idea does work when you connect L&R shifter, run 1 wire to the BB area and include a 5 port junction to plug in:
Battery
RD
FD
shifters
leave one "port" open
This is a good set up for tandems or for bikes like cyclo-cross bicycles that you want to keep the junction A away from a pressure washer. The junction will fit inside the BB area if the access hole made for Junction B is large enough or if you have the patience to fish all the wires to their exit ports simultaneously.
That is how I wired my AR, there are no Di2 holes in the frame except the exit hole for the F/D and R/D. Nothing at the top tube/head tube and nothing at the BB area.
-SD
https://www.kickstarter.com/...bike-for-the-new-era