Well this had lots of parts but is pretty cool. Basically with the older Ultegra Di2 system, you need to add a wireless transmitter to update it and for it to give you gear and other information. It's not really documented how to make this all work, so here's a quick guide:
- DN101 Battery. First you need a new battery as it has the additional memory
- You need to update the battery firmware by downloading a Windows application and plugging it into the battery charger for the Di2 system with a USB A connector
- Then you need to go buy either the EW-WU101 which plugs in at the derailleur or the EW-WU111 which is inline and plugs in inside the frame or at the front junction box.
- You need to buy this little plastic tool to plug and unplug the DI2 wires. There is a no really clear instructions for how to do this, so you have to search YouTube, but basically to unplug it you take the rounded end and it grips the wires and you pull to pop them out. To plug them in, the wire goes in along the longer axis and then you use it to push it in.
- Now download the IOS or Android Phone or iPad application from Shimano called E-Tube (don't get me started on the names!).
- Now to get it to connect with Bluetooth LE, there's a tricky part. Click on the junction box button that is underneath. Do not hold it otherwise you will change the shifting. As soon as you see the red and green lights blink alternatively on the junction box (either underneath your stem or in the bar tube). Stop.
- Now to to the application and hit connect, it will force you to set a new passcode for bluetooth (the default is 000000). Don't forget that code!
- You can now look through the various parameters and select what you want. The most important is to update the firmware (so you no longer have to drag your laptop out to update the shifting system.
This is all pretty cool, so now with this unit, you can use ANT+ or BLE compatible systems to read:
- The current gear you are in
- The battery state of your shifting system