I am busy building an ebike with Shimano components, but I would like to know how to connect all of these components. I have gone through quite a lot of manuals on the Shimano website and e-tube forums, but everything is related to the SC8000 units.

  1. Shimano EP8 motor
  2. SC-E5003 cycling computer
  3. SW-M8050 XT Di2
  4. XT derailleur

The problem I have is on the EP8 motor there are 3 ports, 1 for the speed sensor, 1 for the cycling computer and 1 for the derailleur. there are no additional ports on the SC-E5003 to connect the switch with. only one port which needs to be connected directly to the motor.

on the SC-8000 units there are 4 available slots, but only one on the SC-E5003.

How do I connect the switch to complete the installation?

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1 Answer 1


SC-E5003 is not listed in the dealer manual for DU-EP800, so I don't actually know whether everything going on here is going to work and therefore this is a "suggestion" type answer. That said, it would seem like if there was a way to connect all those components together, the way to do it would be use one of the under-the-stem type Junction A boxes. The DM document seems to be saying that the motor port in question can run to either a "dumb" Junction A box that the other display and control components are all run to, or one of the computers that has display and assist control built in but also acts as a junction for the switches.

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  • 1
    Thank you @nathan, I went to look at the packaging and i found a junction box SM-JC41 and I think this might be the way to get around the issue. I also searched for that specific junction box and looking at page 35 of this manual si.shimano.com/api/publish/storage/pdf/en/dm/SCSW001/… it seems that you have to connect both the display and the switch to the one end and only one wire out to the motor. will test it out and provide feedback. Jul 4, 2021 at 16:12

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