Custom hidden Di2 satellite buttons

With the advent of Shimano Di2 comes the opportunity for satellite shifting buttons. Shimano make their own, thumb shift buttons for climbing on the tops and sprinter buttons for shifting in the drops. I was interested in the climbing buttons, but they are huge (and expensive) for a simple up/down button combo.



Ideally, you could buy the thumb shift buttons, strip off the massive case and buttons and make your own smaller set, but that's expensive and not much of a DIY approach. I had the desire to make some hidden satellite buttons that did the same job but where much less obtrusive. One thing you do need to buy is the plug that will connect the buttons to the shifter. This isn't something you could easily make yourself, nor find freely available for sale separately.



To make satellite shifter buttons for the RD, I wanted some small waterproof buttons and eventually settled on Omron B3S 1002 buttons. I also need a cable set that would provide me with a plug for connecting the buttons to the right hand shifter. The cheapest way I could find of doing this was to buy a SW-7971 cable extension set which is normally used to run between TT bar end button and TT brake shifter/levers.



Once I had the cables and buttons it was time to start work. Asking around some forums I managed to save myself some time doing testing and was told that I needed to connect the green wire to both buttons and then red and black to one button each for up and down shift. The cable was cut to length so all I needed to do then was solder on the buttons and I should have a working system.



My buttons are quite small, 6.6mm across with the button itself only 3mm across. The plan was to hide them under the bar tape, in the groove or hollow made my the brake cable. The buttons had 4 terminal each, 2x +ve and 2x -ve. I only used one of each. Excuse my soldering skills. It's not something I do much of and I'm sure my soldering iron is cr*p. I've since fixed up the red wire. I may eventually make another set and get someone a bit more handy at soldering to do a better job. Instead of splitting the green wire, I just removed the plastic coating from a small section to add the first button.





I plugged the cable into the spare socket on the right hand lever and had success. Both up and down buttons work. I've actually got the buttons the wrong way around to how I would like them. The way they install, the button closest to the stem shifts the chain down the cassette. That is opposite to how I would prefer them to be. Another thing to fix if I make another set. While the buttons themselves are water proof, the next step is to set all the wires and contacts etc. into some silicon sealant. Again, I did a messy job of this and will get a friend who does this stuff all the time to do a better job for me next time.



Installed on the bike. I rewrapped my old tape which just isn't going to work, so I've since put new tape on tomorrow. The buttons are completely hidden and work fine (I now know exactly where they are so can put my finger right on the button). As you can see I use two layers of tape, which reduces the 'feel' of the buttons but I can still feel the 'click' as they depress.





I did this mod at the beginning of March and at the time of writing it is mid June. The buttons have have worked perfectly, matching the rest of the Di2 groupset. My bike is washed every week and I've done plenty of wet rides and my water sealing seems to have worked. I don't think I could do without these buttons now. I often find myself wishing I'd made a set for front shifting as well.



The double taping makes them a little harder to find than I would like on occasions and I think with a single layer of tape the buttons would be spot on. I normally however just put my hands in the correct spot on the tops so I can just squeeze with the appropriate finger and change gear. I regularly just change gears for no reason because it's so cool and I made it. I don't get any accidental shifts with the hidden buttons, although I occasionally bump them when putting my bike in the car.