Part I. I just thought I would share my experience and thoughts on the new XT Di2 system. I am a mechanic on weekends at a local shop, so I am able to have access to the Shimano S-Tec online technology education and certification. I completed around 140 different modules in the past year, which has some side benefits, such as being eligible to buy some components at a discount, and any time you complete any courses in a given month, you are automatically entered into a monthly drawing. I won one of the monthly prizes for completing some modules in June and was notified in July that I would be receiving some new XT Di2 components. After several delays, the good finally shipped withing the past week. I received the last of the items on Tuesday, and completed the installation Tuesday night. Had my first ride on Wednesday night. The Installation I was able to get a Shimano XT Di2 upgrade installed on my 2016 Stache 9 last night, and got my first real ride in on it this evening. The installation went pretty smoothly all things considered, but there were a couple things that needed to be worked out. Before hooking anything up, I downloaded the E-Tube software, then connected all the parts together on the work bench, and connected it to my laptop via the USB cable provided with the SM-BCR2 battery charger. It indicated that some firmware updates were needed to at least some of the components, so that was done so all of the components would have the latest firmware installed. I was hoping to be able to use the E-Tube software on my iPhone to program, but as far as I can tell, it will only work with an iPad. Somebody please correct me if I am mistaken on this as it would be nice to connect with bluetooth. On to the installation. . . . It's difficult to estimate the length of the wires needed. Ideally, you would have access to all the sizes available as you're installing the system. I actually did pretty well on two of the three wires I needed. I totally missed on the third one, but was able to get the wire I needed with one trip to the shop where I work. I actually bought two, and will return the one I don't need (didn't even need to take it out of the box as the first size I thought it would be was perfect, but more on that later). The first part I installed was putting the battery (BT-DN110-1) inside of the battery holder (SM-BTC1). The battery holder is the type that mounts to one side of a bottle cage on the down tube. The mount is designed to attach the same way that many mini pumps do, with the mount being placed under the bottle cage. Installing the battery into the holder was easily accomplished by following the instructions. There is a tool furnished with the shifter (SW-M8050-R in my case) that is used to push the wire ends into place (and it removes them too). It's possible to do it without the tool using just your fingers, but the tool makes it easy, and less likely damage something. The SM-BTC1 is designed to mount on the non-drive side of the down tube, but unfortunately for me, there is a cable guide that interferes with the holder on that side of the down tube, so I ended up flipping it over and mounting it on the drive side. If it were mounted on the non-drive side, the part of the holder that mounts under the bottle cage is smooth. When it is flipped over, the under side of that part is relieved in places, so aesthetically it does not look great. I may modify the holder so it fits on the non-drive side by cutting away that section, but for the time being it is mounted on the drive side. It looks pretty clean, but would look better on the other side. Functionally, it is just as good on one side as the other as far as I can tell. Once the wires are connected to the battery, and the battery is mounted to the frame, it was time to install the rear derailleur. The rear derailleur (RD-M8050-GS) is like a low-normal design as it is in the granny gear position by default. I am running a SRAM 10-42 cassette, and the jockey wheel was hitting the large cog as I installed the derailleur. Once the derailleur is in place, I put the chain on and and as the jockey wheel cage swings forward, the jockey wheel no longer hit the large cog on the cassette. I did a little adjusting of the B-screw to get it up close to get it adjusted properly. The wire for the rear derailleur is 750 mm and fits perfectly. It would not have bothered me to have a little more, but the 750 mm wire is fine. On my bike, the rear triangle has internal cable routing, and the original cable housing had a sheathing over it for the entire length as it passed through the chainstay. The wire ends were not quite slim enough to pass through the sheathing, but I was able to get the sheathing over the end connector and use it to pull the wire through. It would be nice to have some sort of grommets to fit around the wires as they come out those holes, so I will keep my eye out for a clean solution to address that. I can envision the day coming soon, where bikes and components are made to accommodate electric shifting parts more elegantly, and vice versa. However, for the time being, since this technology is still relatively new for MTB's, it can still have some rough edges, aesthetically speaking, here and there in some applications. The controls in the cockpit were next up to complete the installation. The Stache 9 also has internal cable routing for the rear shifting cable through the down tube. However, as with the swing arm, the holes in the down tube and the removable 'bezel' mounted at the lower hole are not big enough for the wire ends to pass through. So, I ran the wire that connects the battery to the display unit (1200 mm in length) along with the rear brake hose and the dropper post housing on top of the down tube in a neat bundle. Not quite as elegant as internal routing would have been, but not terrible either. As the wire leaves the top of the down tube, I just zip tied it to the rear (right side) brake hose as it comes around the front of the head tube. Once it passes by the front of the stem, it then routes over to the display unit (SC-MT800) and connects to it on the bottom of the unit. I do a lot of night riding, and use two lights on my handlebar, with one mounted on each side of the handlebar right up against the stem. So, the display unit is an inch or so away from the stem, but still on the thick section of the bar. from there, another wire runs over to the Firebolt shifter unit (SW-M8050-R). I originally got a six inch wire to connect the display unit to the shifter, but the way it exits the shifter, it makes a 180° bend and doubles back onto the shifter to get it back to the handlebar with the cable being vulnerable to being snagged. It then runs along the handlebar over to the display unit. The six inch (150 mm) wire would run in a straight line over to the display unit, but in order to run it cleanly, it needed a wire twice that length (300 mm). I used electrical tape in two places to attach the wire to the bar as it runs from the display to the shifter. As per the instructions, I filled the third connector hole on the display unit with a provided dummy plug to keep moisture and dirt out of that connection point. At this point, the system is ready to fire up and perform the final adjustments. One press of the mode button will light the display unit (briefly) and let you know the system is functioning. I turned the pedals and activated the shift button to shift down the cog all the way to the smallest cog and the limit screws appeared to be OK at both ends of the range. I then (as per the instructions) shifted to the fifth cog, pressed the mode button for two seconds, which entered 'adjustment mode', which was indicated on the display unit by it showing an "R". Then I turned the pedals and pressed the downshift paddle a couple times until I could just hear the chain hitting the fourth cog, and then hit the upshift paddle five times to get it back to the correct index point (still) on the fifth cog. This is how the instructions say to do it. It was quick, and it was easy to do. A quick late night test ride in the street confirmed that it was working well, but the real test ride would take place the following day. The 'length' of the shift paddles can be adjusted, and I adjusted them to be at their longest so the digits on my XXL hands reached them comfortably with my hands in their normal position on the grips.