Captain_Canada

Is one better than the other? I don't really like the looks of the under the stem box/rubber band.

Also, with the bar end box available, why do some manufacturers go through the trouble of bringing the box into the frame? Danger of the bar end getting knocked in a crash?

I've never had electronic shifting but am thinking of my next bike.

MidTNBrad

I have the 6800 version of Di2 (previous version) and have the external junction box because the bar end wasn't available. I'd go with the bar end if I were purchasing now.

I got one of these to clean up my stem.
Di2 mount

eflayer

2019 Roubaix is the bar end. 2020 Roubaix is integrated into the molding of the frame and now in the downtube. under the stem is first phase and the least aesthetically please but maybe the easiest to deal with if any wrenching is needed.

Steve B.

Putting the A Junction into the bar end is reasonably out of the way, except when I think how many times I’ve knocked off a bar end cap. As well the h-bar needs holes to allow cables to route to the downtube, so handlebar purpose designed.

Falchoon

Stem mounting is a lot cheaper. Bar end is more aesthetically pleasing. If I had a choice and they both cost the same then I would go for bar end.

alcjphil

If this were my case I would look for bikes that had the box located in the frame

popeye

I run bar end but stem mount is much easier if you have to trouble shoot.

NoWhammies

If I had the choice I'd go with the bar end. Just looks nicer.

Noctilux.95

Bar end junction boxes exist due to the nastiness of the under the stem version.

Seattle Forrest

How much does it cost to change over? Or is that only possible on newer versions?

I actually like the junction box under the stem. Di2 has been out for a long time, it used to always be under the stem ... I've seen so many nicer bikes than mine and many of them had that tell tale band holding the junction box in place. Feels like I've arrived or something.

But everything is set up nicely, and I bet that extra stuff costs me a few watts. It's not like I'm going to be getting many more as I age. Need every advantage I can get until the day I need an eBike to crash Strava KOMs.

Steve B.

Never heard it referred to that way. “Nasty ?”. I know some folks don’t like it as it’s not a clean look. On some stems the band is noticeable and I guess that bothers people, but there are mounts that replace a few stem spacers, so cleans that part up. I have no issue as my bar is cluttered with a front light and my Garmin mount, so the A Junction is hardly noticed. If I didn’t have a Garmin which shows me what gears I’m in, I would use the XT stem display.

But everybody has things they like or not.

rm -rf

I wondered how that worked, mounted into the frame. This looks practical, with all the junction wires in the frame and it's easily serviceable with removing one screw.



You can easily see the status lights while riding.
I do check the charge level on my 6800 under stem box. Just hold a shift button for more than a second and the box shows four levels of charge: green: 100-50%, blinking green: 50-25%, red:25% to minimal, blinking red: almost out.

I recharge soon after it shows blinking green. No need to let it run down farther. I just installed a replacement seatpost battery, after 5 1/2 years. The old one still worked, but it had to be recharged quite often.

Di2 was stupidly expensive back in Sept 2014, when I got the new bike. But it's been worth it, I really like the instant, drama free shifting. And the shifters and derailleurs are working like new. No noticeable wear in the derailleur pivots and it still shifts perfectly.

bahula03

The only real function difference between the SM-EW90A/B (under stem) and EW-RS910 (bar end/frame) is the number of ports, 3 or 5 for the SM-EW90 and 2 for EW-RS910, which only matters if you're adding accessories like sprint shifters or the climbing shifter...and don't have open ports on your levers.

Like others have mentioned, the EW-RS910 requires bars that have holes to route the wires, so you're constrained by that for upgrades/different sizes. Some manufacturers will use the EW-RS910 and route the wires through both the bars and stem, which means having to find both components that are compatible. None of it's a big deal really, just preference on what it looks like, supporting components, and how easy/difficult it is to install.

jmess

I really like my the SC-MT800 System Display installed on my Bianchi XR4. The display has 3 Di2 ports and clamps to my handles bars.You can get one from Universal Cycles for $90. It works perfectly with the Road Di2 components. The display comes on every time you shift or touch the mode button. I have the display timer set to 30 seconds ( via e-tube-project configuration). I was having problems with my Di2 battery being run down by a Shimano Di2 inline Bluetooth module, it wasn't shutting off at times. The MT800 connects to my phone or Garmin 1030 with no problems. Firmware updates are easy via e-tube-project.
The SC-MT800 System Display is the brains of Shimano's XT Di2 electronic mountain groupset, allowing you to view data, control settings, and connect to the E-Tube Project application to customize your shifting preferences. Bluetooth and ANT+ enabled, the MT800 system display wirelessly connects to smart devices and cycling computers for seamless operation and control anywhere you go.
Details:

• Displays system status of: battery level, gear position, shift mode and FOX iRD suspension position
• Toggle audible shift notification chimes
• Toggle between three Shimano Synchronized Shift modes available (S1/S2/Manual)
• Digitally adjust front and rear derailleurs and provide numerical adjustment indicator
• Wireless ANT / Bluetooth communication for customization and data utilization in the field with a smartphone, tablet, and other mobile electronics
• Battery charging port
• 3 E-Tube ports
• D-Fly compatible

Chi_Z

bar end is the way to go, but if you have older handle bar you have to drill out a hole

TerryDi2C

hah, nice - I installed one too (bought to help a user that was having problems pairing theirs).



Personally I don't see the use of this unit on a road bike, but that is just my opinion (I already have my Wahoo that displays the same data). It is perfectly fine to have a different opinion

That said, there are a couple of things I do like:

• The audible shift notification chimes are pretty neat.. It beeps when I'm at either end of the cassette and also right before a (full) synchro shfit.
• The button seems to work better than the one on my SM-EW90-A (not installed the EW-RS910 yet... soon..)
• Because it's a display it is easier to tell the battery level, current shift mode and 'adjustment mode'. It also tells you the current RD / FD adjustment value

It'll probably stay on my second bike, because my EW-WU111 is moving to my new bike (Bowman Palace 3) soon.

The "D-fly compatible" in jmess' list means that this will do the same as a D-fly (BluetoothLE and ANT) - you can not install both this and a D-fly on the same bike (only one wireless capable device per Di2 bike allowed).

Greatestalltime

Or, apparently, if you have Most Talon bar stem combo. Just bought some to replace the Metron 6D which has the hole pre drilled, but didn’t fit with the f8 frame very well.

I was surprised the Most didn’t have it. The drilling is no big deal though. I have had the shop do it on a pair of FSA and Deda. Both carbon. And now the Most which is almost finished.

Rs-910 is the only way to go imo. And as I said drilling the hole isn’t a big thing.

avhed

I guess I need 31.8 diameter bars?

Kimmo 

How about inside the stem?

Bald Paul

You could always go with SRAM E-tap and just forget about all the wires and junction boxes.
I have a bike with Di2 and went with the bar end box with handlebars designed for internal wiring, but to be honest, if I were to build another bike (as soon as I hit the lottery) I'd either go SRAM wireless, or wait to see if Shimano goes that route.