I'm having problem testing my Di2 setup. Long story short, I got a pair of used but in very good condition Dura Ace Di2 9070 brifters for a cheap price. I then bought a new Di2 cable set with external battery mount, external junction SM-JC40 and the SM-EW90 junction A. For the RD I bought an Ultegra R8050 RD, also in a very good condition since the shop said they just took it off a new bike. The batteries are the SM-BTR1 with around 50% charge, as indicated on the junction box when I plugged the cable into it. Currently I'm missing an FD.

Now the problem is I want to test whether the setup works out of the box without firmware update so I plugged everything in, checked the connection etc, but the shifter isn't doing anything and the RD doesn't move. Holding the shifter button also doesn't show the battery level. So my question is: Is it normal for Di2 to not work without the left shifter and FD connected? Or is it really a firmware problem?

Thanks in advance.

  • I think you need that front derailleur in a road system for it to function. Shimano have a good troubleshooting guide but you're just as easy downloading the etube software and plugging it in to the computer
    – Noise
    Apr 20, 2021 at 11:04
  • I guess I won't be able to know before I buy an FD then. Problem with troubleshooting is that I have to buy the BCR2 as well, which I will in the future. Apr 20, 2021 at 11:50
  • Also: the derailleurs have to be from the same family to work together.
    – Carel
    Apr 20, 2021 at 11:54
  • If you aren't aware of bettershifting.com, that site may have useful information. Posting as a comment because I haven't gone through it. To my knowledge, Di2 can operate in a 1x setup. I believe it does not need to have an MTB rear derailleur to do this. I'm not certain if there are any intermediate steps involved in setting it up as a 1x.
    – Weiwen Ng
    Apr 20, 2021 at 12:18

1 Answer 1


Okay problem solved. Apparently the NOS cable set that I bought came with an SM-EW90-A with really old firmware. After installing E-Tube Project v3.4.5 and restarting my laptop, I was able to update the junction box using SM-BCR2. The RD works without the FD mounted and I was able to make initial adjustment while waiting for the FD. Thank you for all your comments and hopefully we learn something new everyday!

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.