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Di2 1x wiring question
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Ok so I am moving forward with a 1x11 Di2 conversion. I am trying to understand if I need both an A and B junction box:
AND

I need the right shifter, and rear derailleur to be connected to the battery.

Would I be able to mount the 3 port junction near the BB and run 3 e-tubes to the battery, shifter, and derailleur?

/kj

http://kjmcawesome.tumblr.com/
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Re: Di2 1x wiring question [kjmcawesome] [ In reply to ]
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You have to have a 3/5port junction box in the system somewhere. The 4port is only a dumb connection housing used to connect nodes (deraileur, battery, shifters...) to the system if required.

You can run your 1x10 off just a 3 junction box if your wires are long enough. This is exactly how my TT system is done. I have the junction box stuffed in my seat tube near the seatpost battery. A single wire runs from the junction box to each of the nodes (Battery, RD, right shifter).
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Re: Di2 1x wiring question [Pantelones] [ In reply to ]
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Awesome. I thought the "B" junction was a dumb box.

I am retrofitting a 2004 Madone, so unfortunately everything will have to be external. It does save a few wires and clean things up a bit with just a single wire running down to the downtube.

Now I just need to figure out how/where to mount the 3/5 port box. I'm assuming I can just use this strap and mount it to the downtube/seattube/seatstay near the BB and run a short wire to the battery and longer one to the rear derailleur.

Any other ideas on wiring? Maybe mount the battery to the drive side chainstay to keep everything lined up?

/kj

http://kjmcawesome.tumblr.com/
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Re: Di2 1x wiring question [kjmcawesome] [ In reply to ]
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I am using a DI2 1x11 setup without any problem.
SW9071 Shifters, 3-port junktion under BB, Ultegra DI2 RD medium cage, SM-JC41 inside the stem, battery inside seat-tube.
All mounted on a Boardman Air TTE.
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Re: Di2 1x wiring question [Timo74] [ In reply to ]
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Thank you. I think one button per shifter is ideal on a TT bike. One for a bigger fear, the other for a smaller gear. Simple.

/kj

http://kjmcawesome.tumblr.com/
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Re: Di2 1x wiring question [kjmcawesome] [ In reply to ]
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kjmcawesome wrote:
Ok so I am moving forward with a 1x11 Di2 conversion. I am trying to understand if I need both an A and B junction box:
AND

I need the right shifter, and rear derailleur to be connected to the battery.
Would I be able to mount the 3 port junction near the BB and run 3 e-tubes to the battery, shifter, and derailleur?

As others have said, you don't need B. You don't really need A either as you could use the smaller EW6770.

I don't have a 3 port or 5 port on either of my Di2 bikes.

-SD
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Re: Di2 1x wiring question [kjmcawesome] [ In reply to ]
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The comments about the junction boxes are correct. As for mounting the pieces I've seen a photo of the Junction A box mounted using the OE strap to the seat tube below the bottle cage and near the FD (if you had one). I'm not familiar with a 2004 Madone but wonder if the external battery mount from a later one (e.g. the Di2 kit for my 2012 6.9SSL included a short mount) that fits under the BB could be made to work on your bike.
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Re: Di2 1x wiring question [SuperDave] [ In reply to ]
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SuperDave wrote:
kjmcawesome wrote:
Ok so I am moving forward with a 1x11 Di2 conversion. I am trying to understand if I need both an A and B junction box:
AND

I need the right shifter, and rear derailleur to be connected to the battery.
Would I be able to mount the 3 port junction near the BB and run 3 e-tubes to the battery, shifter, and derailleur?


As others have said, you don't need B. You don't really need A either as you could use the smaller EW6770.

I don't have a 3 port or 5 port on either of my Di2 bikes.

-SD

So what would the setup look like if I used the EW6770? It seems like I would need some female-female adaptors in order to run a wire long enough to get to the shifter or rear derailleur.

I am imagining the EW6770 near the BB (2004 Madone, so no internal wiring) with one of the cables connected to the battery and a long cable running from the female port of the EW6770 to the shifter. That leaves me with one of the male ends reaching about halfway down the DS chainstay, short of reaching the rear derailleur.

/kj

http://kjmcawesome.tumblr.com/
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Re: Di2 1x wiring question [Quattroporte] [ In reply to ]
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Any idea where I can find a BB battery mount? I have seen several that look like they screw into the BB cable guide hole like this (obviously my cables would be routed externally):


I'm thinking where the "traditional" battery placement would be ideal for the junction box as well. It would be protected from road spray by the downtube.

/kj

http://kjmcawesome.tumblr.com/
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Re: Di2 1x wiring question [kjmcawesome] [ In reply to ]
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I don't know about the Cannondale bracket. There is one in the previous generation Madone Di2 kit. The part number for the kit is 419125. I'll look over the weekend to see if the bracket has a separate number. As I recall, there's not much in the kit: the battery mount, a different internal shield for the BB and some grommets and plugs. Everything else is Shimano.
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Re: Di2 1x wiring question [Timo74] [ In reply to ]
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I've been thinking about running a 1x TT setup, it's pretty flat here in the Midwest.

Do you run a 32t on the med cage?
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Re: Di2 1x wiring question [robwhittier] [ In reply to ]
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I finished the project and should post some pictures. I'm currently running a 42x11-28 with the Dark Speedworks hack on an 11 speed cassette. After about 75 miles, all is good. I think ideal gearing would be more like 46x11-32, but this isn't a race bike and I haven't minded just coasting when I spin out in 42x11.

There doesn't seem any downside to running the GS (medium cage) rear derailleur, and with the new Wolftooth Goatlink, you could run the Shimano XT 11-40 rear derailleur. With 50x11-40, that would be a super wide range, but there would be some larger gaps.

/kj

http://kjmcawesome.tumblr.com/
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Re: Di2 1x wiring question [kjmcawesome] [ In reply to ]
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Sorry for resurrecting an old thread, but am looking to do a very similar 1x build and there's very little info out there!

Building out a P3 frame, plan is a single TT shifter (the 2 button one) and an Ultegra 8050 rear derailleur (consensus seems to be that this works fine for 1x road use, will obviously have a narrow-wide chainring). Have the Tririg bars so planning to put the junction box in the stem where it's easily accessible.

Questions are therefore:
- Am assuming I only need a single 3 port junction box as I have only 2 components (shifter plus RD) to connect?
- Can I connect battery directly to the third port in the junction box or do I need a Y cable so that battery plus RD both come into one port?
- If I need a Y cable then they only seem to come in max length of 520mm which isn't going to work with a stem-mounted junction box, so how do I securely extend the cabling to reach the RD and battery?
- Any other bits and pieces needed to secure wires, route them round the BB or anything else internally? I have Di2 on my road bike but it came pre-built and I've never opened it up to investigate...
- (bonus question) Best place to put the battery in current model P3 frame?

Thanks in advance for any help!
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Re: Di2 1x wiring question [cartsman] [ In reply to ]
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If I am understanding correctly, 3 port will be fine with proposed setup. B-junction at BB with 3 wires in: 1) one from 3 port; 2) one from battery in seatpost (or seat tube if it has mount); 3) one to RD

Cheers!
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Re: Di2 1x wiring question [ktm520] [ In reply to ]
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ktm520 wrote:
If I am understanding correctly, 3 port will be fine with proposed setup. B-junction at BB with 3 wires in: 1) one from 3 port; 2) one from battery in seatpost (or seat tube if it has mount); 3) one to RD

Cheers!

Thanks - so I still need a B junction and can't just plug battery straight into the A junction?
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Re: Di2 1x wiring question [cartsman] [ In reply to ]
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cartsman wrote:
ktm520 wrote:
If I am understanding correctly, 3 port will be fine with proposed setup. B-junction at BB with 3 wires in: 1) one from 3 port; 2) one from battery in seatpost (or seat tube if it has mount); 3) one to RD

Cheers!


Thanks - so I still need a B junction and can't just plug battery straight into the A junction?

I would personally leave the option for basebar shifting via R9150 remotes in other 2 ports and the wire from RD to 3 port may be a literal stretch, although you could use extender, your choice. I tried exclusive aero shifting and due to my riding preferences (hilly verus flat) I added basebar hidden under bar tape on basebar.

Cheers
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Re: Di2 1x wiring question [cartsman] [ In reply to ]
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cartsman wrote:
ktm520 wrote:
If I am understanding correctly, 3 port will be fine with proposed setup. B-junction at BB with 3 wires in: 1) one from 3 port; 2) one from battery in seatpost (or seat tube if it has mount); 3) one to RD

Cheers!

Thanks - so I still need a B junction and can't just plug battery straight into the A junction?

You can connect the battery directly to junction A. The B junctions have no chip and the system has no idea they are or aren’t there. The max e-tube cable length may mean you need a junction B of some type to get the run to the RD. There is a two port junction B. It isn’t any cheaper than the 4 port, but is quite a bit smaller.

For your setup it would be worth checking to see if the battery will fit in your left aero extension.
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Re: Di2 1x wiring question [cartsman] [ In reply to ]
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cartsman wrote:
ktm520 wrote:
If I am understanding correctly, 3 port will be fine with proposed setup. B-junction at BB with 3 wires in: 1) one from 3 port; 2) one from battery in seatpost (or seat tube if it has mount); 3) one to RD

Cheers!


Thanks - so I still need a B junction and can't just plug battery straight into the A junction?

You could indeed skip the B junction. The 3 ports would be:
  • to the shifter
  • to the RD
  • to the battery

However, those would be two rather long wire runs since mounting the battery in the seatpost is usually the best.
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Re: Di2 1x wiring question [SummitAK] [ In reply to ]
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Thanks - so effectively you can plug whatever you want into junction A and it's smart enough to figure out what's at the other end?

Looks like the e-tube wires go up to 1400mm which seems like plenty enough if I go down the ultra-simple route, guess the only downside is that if I change my mind and decide in the future I want brake shifters or a 2x setup then there's a few more parts to replace than if I build in a junction B now.
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Re: Di2 1x wiring question [cartsman] [ In reply to ]
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cartsman wrote:
Thanks - so effectively you can plug whatever you want into junction A and it's smart enough to figure out what's at the other end?

Looks like the e-tube wires go up to 1400mm which seems like plenty enough if I go down the ultra-simple route, guess the only downside is that if I change my mind and decide in the future I want brake shifters or a 2x setup then there's a few more parts to replace than if I build in a junction B now.

Yes. Essentially. All components except e-tube wiring/splitters and B junctions have a chip in them. The system only needs them interconnected by some method. The only non-starter I can think of is the use of two Junction A's in the same system.
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