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Questions about Di2 and integration with bike computers

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Questions about Di2 and integration with bike computers

Old 10-31-19, 09:00 PM
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tmhudg
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Questions about Di2 and integration with bike computers

Hi All,

I've recently ordered a Co-Motion Steelhead with Di2 (I'm getting flat bars and therefore the MTB shifters if that matters at all for the questions below).

Before this I had a Trek T2000 which had a Shimano Flight Deck computer. I loved that computer because it showed me which ring and cog I was in at a glance so I could make sure I was in the right gear when coming to a stop or whatever. With the Di2, my understanding is that in order to get gear indication, I either have to get a Shimano System Information Display or integrate it with an ANT/Bluetooth cycle computer such as the Garmin 530/830. It sounds like I need to get an extra component to be able to do this - A wireless unit D-Fly? Looks like there are two types - a Wireless Unit D-Fly and a Wireless Unit D-Fly 2 port junction. The Shimano site doesn't really explain the difference between the two as far as I can see. I've read about A ports and junctions and I don't really have a clear understanding of how it all fits together.

Does the D-Fly get plugged in inline to the battery in some fashion? Is the difference between the two types basically the way they are mounted? It looks like one might mount externally and the other go in the seat tube along with the battery???? If I drop the D-Fly unit in the seat tube will it be able to connect with the stuff on the outside? I'm sure I'm missing some resource that clearly explains all this but I'm just not clear.

I'm leaning towards the Garmin since I want navigation and the TrailForks integration sounds interesting. I don't want to start a Wahoo/Garmin debate - I've read a bunch on that aspect - although I'm open to thoughts on that as well.

Thanks for any help/advice.
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Old 11-01-19, 09:27 PM
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You will need either an xt/xtr display in lieu of juntion box A, sc-mt800/sc-m9051, or the wireless inline ew-wu111. Either option must be used with the newer bt-dn110a battery in order for the garmin headunit to communitate with your di2

Co-motion ships the stealhead with what i beleive is the longest di2 cable to go from the A junction all the way to the B juntion in the stoker bottom bracket. On the stock medium frame this meant the sc-mt800 had to be installed to the left of the stem blocking the charge port. If you are going to go with the display unit i would ask them to spec with a 2 port b juntion in the captain bb and a second B juntion in the stoker bb. This would allow you to get a cable long enough to put the display where it is meant to be to the right of the stem.
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Old 11-02-19, 01:02 AM
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Agreed, the MTB display or inline wireless unit are what you need. If you have the MTB display, you may not even bother to connect it to your computer because that display already gives you all the info you need.

BTW, I run the XT front junction box to the left of the stem because the clamp mount works better on that side in my setup. The only drawback is that you have to loosen the clamp and rotate the display to access the charge point when you need to re-charge.
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Old 11-03-19, 02:02 PM
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Looks like there are two types - a Wireless Unit D-Fly and a Wireless Unit D-Fly 2 port junction. The Shimano site doesn't really explain the difference between the two as far as I can see. I've read about A ports and junctions and I don't really have a clear understanding of how it all fits together.

The functionality of the EW-WU111 and EW-WU101 is the same, they just look different. The EW-WU111 is place in-line (with a port on each end), between junction A and a shifter or between junction A and junction B for example.

The EW-WU101 has two ports on one side and is a bit bulkier. This unit is usually placed near the rear derailleur (seat stay).
Either way, you can put both wherever you like, but Shimano recommend you place the EW-WU111 near the front of the bike. Mine is in the handlebar, but whatever works works .

If I drop the D-Fly unit in the seat tube will it be able to connect with the stuff on the outside? I'm sure I'm missing some resource that clearly explains all this but I'm just not clear.

Possibly. Try and find out .

Have a look at page 62 of this document for EW-WU111 installation instructions: https://si.shimano.com/#/en/DM/R8050 and this document for the EW-WU101: https://si.shimano.com/pdfs/dm/DM-RBWU001-05-ENG.pdf

But yeah.. the MTB "System Information Displays" also feature wireless(bluetooth/ant) connectivity - the MT800 and SC-M9051 (not the SC-M9050).

Last edited by TerryDi2C; 11-03-19 at 02:08 PM. Reason: clarification
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Old 11-04-19, 08:34 AM
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Originally Posted by ahultin View Post
...On the stock medium frame this meant the sc-mt800 had to be installed to the left of the stem blocking the charge port. If you are going to go with the display unit i would ask them to spec with a 2 port b juntion in the captain bb and a second B juntion in the stoker bb. This would allow you to get a cable long enough to put the display where it is meant to be to the right of the stem.
Originally Posted by Chris_W View Post
BTW, I run the XT front junction box to the left of the stem because the clamp mount works better on that side in my setup. The only drawback is that you have to loosen the clamp and rotate the display to access the charge point when you need to re-charge.
Noted but what causes the display to be forced to the left side of the stem? Do the wires enter the frame on that side and there's not enough length to put it on the right?

Originally Posted by TerryDi2C View Post

Have a look at page 62 of this document for EW-WU111 installation instructions: https://si.shimano.com/#/en/DM/R8050 and this document for the EW-WU101: https://si.shimano.com/pdfs/dm/DM-RBWU001-05-ENG.pdf
Thanks for these links!

Thanks everyone, for this info.
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Old 11-04-19, 09:43 AM
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Hmm, something I just noticed from the Shimano support page is that the System Information Display SC-M9051 is required for Synchro shifting when using XTR. I guess I thought that was "built-in" to Di2. I know there is some debate on how useful synchro shifting is but I thought I would have the option to try it and decide for myself. Sounds like I need to get the display to even have the option to play with. Am I reading this correctly?

https://productinfo.shimano.com/#/lc/xtr_m9050/2x11
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Old 11-04-19, 10:03 AM
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Originally Posted by TerryDi2C View Post

The EW-WU101 has two ports on one side and is a bit bulkier. This unit is usually placed near the rear derailleur (seat stay).
Either way, you can put both wherever you like, but Shimano recommend you place the EW-WU111 near the front of the bike. Mine is in the handlebar, but whatever works works .
A datapoint: Our EW-WU111 is mounted in the stoker seatpost just below the battery and communicates fine with our Garmin 540.
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Old 11-04-19, 10:24 AM
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For the steelhead, the di2 wire exits the downtube on the left. This combined with already having the longest etube wire due to going all the way to the stoker bb resulted in the display only fitting on the left.

In my experience both the xt display and the xtr 9051 display allow for synchro shift
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Old 11-04-19, 10:46 AM
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For the steelhead, the di2 wire exits the downtube on the left. This combined with already having the longest etube wire due to going all the way to the stoker bb resulted in the display only fitting on the left.

In my experience both the xt display and the xtr 9051 display allow for synchro shift
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Old 11-04-19, 01:08 PM
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Originally Posted by tmhudg View Post
Noted but what causes the display to be forced to the left side of the stem? Do the wires enter the frame on that side and there's not enough length to put it on the right?
I have the display mounted on the left because I use aerobars that clamp to the handlebars on either side of the stem, which means that the clamp of the MTB Di2 display only works when mounted on the left side so that it's outside of the aerobar mounting clamps.
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Old 11-04-19, 02:14 PM
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Originally Posted by tmhudg View Post
Hmm, something I just noticed from the Shimano support page is that the System Information Display SC-M9051 is required for Synchro shifting when using XTR. I guess I thought that was "built-in" to Di2. I know there is some debate on how useful synchro shifting is but I thought I would have the option to try it and decide for myself. Sounds like I need to get the display to even have the option to play with. Am I reading this correctly?

https://productinfo.shimano.com/#/lc/xtr_m9050/2x11
Yeah, the compatibility charts state: "SC-M9050, SC-M9051 or SC-MT800 is required for synchronized shift in MTB category"
(https://e-tubeproject.shimano.com/guide/#guide_list)
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