I know really good cyclists „just know“ which gear they are in. Well, I admit, I do not. I actually quite frequently look at the gear indicators of my bikes. My road bike does not have a gear indicator. So while riding the road bike, I often found myself looking down to see which gear I am in. Which was dangerous, and it probably slowed me down.
So I thought it would be nice to see the gears in the bike computer, which I know would be possible by wirelessly connecting the computer to the Di2 groupset of the road bike. And of course it is a nerdy, fun thing to do…
Unfortunately, to do so I did not only have to buy Shimano’s „Wireless Unit EW-WU111“ and a pieace of „Electric Wire EW-SD50“, but also a new battery BT-DN110-A. It turned Rose sold me the bike in 08/2018 with an obsolete SM-BTR2 battery in it, which was manufactured in 02/2016. Pretty bad- considering such batteries also lose some of their capacity over time. The bike was relatively inexpensive for a Di2 bike, though, maybe that’s why they had to scavenge some of the components from a scrap yard.
So first I replaced the battery. In the Rose bike, the battery was hold in place inside the seatpost by 2 pieces of rubber, which I had just to tear out with a wrench. I think usually these batteries are hold by snap rings; I guess Rose’s robber thingies are just as reliable and more service-friendly. After installing the new battery, I connected the bike to a laptop with the „E-Tube“ software. It turned out I had to update the firmware of all components. Which was strange- I checked for firmware updated just recently. Perhaps there is special firmware needed for the components to work with the new BT-DN110-A battery.
Then I took the seatpost out again and connected the „Wireless Unit EW-WU111“ to the new battery with the „Electric Wire EW-SD50“, and stuffed all the cable with the wireless unit into the frame. I think the EW-WU111 is actually meant to be installed somehow at the front of the bike next to the junction box. However, putting it into the frame is neater- and more aero, of course 🙂
Then I connected the bike again to the „E-Tube“ software und updated the firmware of the wireless unit. Probably I could have installed the wireless unit when I changed the battery and I could have done all the firmware updates together. But I was not in a hurry- and I guess it is just good engineering practice not to change to many things at once.
After I set a passcode in the „E-Tube“ software, I could add the Di2 groupset like an additional sensor to the Wahoo Element Bolt using the smart phone app. In the display (page) settings of the bike computer I could then chose to show the gear setting.
All in all, it was easier done than I thought. No special tools were needed, and the „E-Tube“ software is pretty user-friendly. And now that I see which gear I am in, I am sure that I am much, much faster 🙂
The new battery would also allow for synchro-shift, and the wireless connectivity would also allow to control the computer with the hood switches. But I do not yet know if I need those features.