Is it possible to use 2 junction A boxes in Di2 setup (RS910 and EW90) .If you ask why i need a longer cable and i have 2 shorter cables. I wish yo extend the cable with a spare EW90 junction A.


1 Answer 1


Doesn't seem to work. I have a EW-RS910 in the handlebar and plugged an EW90 before the RD. If I use a EW-JC200 instead of EW90, everything works. So you'll either need to:

  1. Find longer cables.
  2. Get a EW-JC200.
  3. Splice the cables. Very easy to do - cut the wires to desired length, slide 3mm heatshrink on, remove the insulation, slide 1mm heashrink on, twist the cable, heat the 1mm heatshrink, repeat for the second cable (there are two - red and black), slide the outer shrink wrap onto the twists, apply heat.
  • You should solder those connections before putting the heat shrink insulation on. Otherwise they can pull apart or oxidize and then stop working, given time.
    – Gary E
    Dec 3, 2022 at 20:56
  • The wires can be soldered for extra sturdiness, true. In three years I've been running twisted wires not a single connection has failed, though. Dec 4, 2022 at 11:22

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