Raysurs

Hello everyone!

I am completely desperate to fix my bike, so I'm trying my luck here with you guys

I have a problem with my KTM Revelator from 2014, equipped with a DI2 Dura-Ace 7970, which is the first generation of DI2 (not using E-tube).

Here's my issue: The right handle won't shift the speed of my rear derailleur.

Here is what I've already done to try to fix the issue:

• I used two fully charged batteries to test if it was a battery problem; both batteries are working fine.
• I replaced all the cables of the DI2 system throughout the entire bike. This was very expensive and challenging since the cables for the first-generation DI2 are no longer made and are different from those used in more recent DI2 systems. Unfortunately, this did not resolve the issue.
• My left handle works correctly and shifts my front derailleur without any problems.
• If I switch the cables between the right and left handles, I can shift the front derailleur using my right handle. However, then the left handle stops working and won't shift the rear derailleur. This confirms that both handles are functioning. Additionally, if I press and hold my right handle, a green light appears on the junction box, indicating it's sending a signal, but it still won't shift the rear derailleur speed.
• I can use the 'crash test mode' of the DI2 by pressing and holding the junction box button for about 5 seconds. This action causes it to shift through all the rear derailleur speeds one by one, confirming that the motor on the rear derailleur is also working.

After the crash mode cycles through all the speeds, it just stops, and I still cannot switch the rear derailleur speed.

Now, I have absolutely no idea what the problem could be. I've tried everything that came to mind, including removing the rear derailleur from the bike to try switching speeds without the chain, but I encountered the same results. I also tried adjusting different settings on the rear derailleur using the three screws (two for cassette settings and one tension screw), but nothing has worked.

If anyone has experienced this issue or could help me solve this problem, it would be amazing!

Barry2 

I’m not familiar with your version of Di2.
But if my R8000 had the same symptoms you describe, I’d suspect the junction box.
I would then switch the ports the shifters use.

Barry

And don’t forget, you can test cables by running them outside the frame.


or….. remove the rear derailleur and plug it into the front derailleur cable.

mpetry912 

if this first version is supported by the Shimano software, I'd suggest trying to do a software update

/markp

Bill Kapaun

I don't know diddly about the new electronic stuff, but your post is one of the best opening posts I've seen in describing "where you are at".

Iride01 

Do you have the eTube software on your PC? What does it show when you connect to it? At least for my 11 speed R8000 version of Di2, it does a check that will show you all the Di2 components that it sees connected to it. If your RD doesn't show up, then I'd first suspect one of the connections in the wires between it and whatever it is connected too. Which doesn't have to be directly to your shifter, IIRC. Those Di2 wires require that you feel two bumps when you push them together. Really helps to have the Shimano tool for that.

You might just ask at a bike shop and see what they'd want to connect it up to their sm-pce02 which will provide more diagnostics than the sm-bcr2 that we get with our Di2 bikes. They should easily be able to tell you if the RD is toast or not.

You spent a lot of money on it just guessing. Especially just replacing all the wires blindly. So spend some money with someone that frequently works on Di2 bikes at a local shop. Preferably not your big box bike shop. But a small owner operated shop where the owner is one of the mechanics.

Barry2 

7970 does not support E-TUBE.

It’s a 4 wire system and not 2 wire E-TUBE compatible.

Barry

Iride01 

Oh! Thanks for the info.

Can a bike shop still diagnose it with their SM-PCE02 or some other gadget Shimano may have made for that version?

Raysurs

First of all, thank you everyone for your responses to my problem!
I'm starting to think my RD is broken, even though it works when I use the crash recovery mode, which is definitely strange to me!

It seems like there is a diagnostic tool that exists for my system, 'Shimano SM-EC79,' but it's very hard to find a bike shop that has it, and it costs around $350 to buy. Since I already spent around $500 on cables, I'm hesitant to spend more on the repair at this point.

I'm considering disassembling the RD to see if I find anything, but the operation seems risky and difficult to do.
I tried two different junction boxes and two different sets of cables, and I still have the exact same problem. I also tried with and without the chain (in case the system had an issue with the chain), and I tried all possible setups on the RD screws for the settings, but nothing made it work. The motor still works all the time through the crash recovery mode, but it will never work using my right lever.

Barry2 

I looked on eBay for RD-7970 pricing, wow.
Have you considered the purchase of a complete set of spare parts? (P series is a tri bike, so wrong levers)

Those on ebay "know what they have", those selling old bikes, maybe not so much.

Barry

Iride01 

Maybe you could take the RD off and take it to a shop to see if they can determine if the RD itself is working. Seems like a few dollars spent for that will be better than guessing and purchasing a new or used RD that still might not work if it's not the actual RD giving you issues.