This project was part of a Shiv custom assembly for a customer at the beginning of this season.
After looking at all the hack/mod options we decided to go with this setup as it didn’t involve any wiring work thus reducing the chance of failure in the future.
By removing the unwanted parts from a Shimano Di2 Brake Shift Lever set you are left with two fully intact sets of Shimano shifter buttons and wiring allowing you to stick with the E-Tube plug and play system. Another advantage to this is that the stock cable is long enough to make it to the junction box eliminating the need for additional B-Junction boxes.
The time needed will very greatly depending on your ability to hold the shifter body safely while removing the excess material with either a hacksaw or a dremel. If you can find a way to clamp the shifter body once you have removed the brake lever you can cut away almost all the unwanted material with a hack saw leaving very little clean up work with the dremel. With the first shifter I mostly used the dremel to determine just how much to cut and where. Once I had the end product figured out I found a more efficient way to cut away the unwanted material with a hacksaw. The second method using the hack saw is what is documented.
With the shift lever now an independent unit there was one more small modification I wanted to do. I was a little concerned about what ever I was going to use to bound the shifter to the brake lever getting inside through the hole in the back of the shifters and affecting the shifter buttons. A trip to the hardware store next to the shop provided me with an almost ideal solution. Only drawback was the material was white when dry not black. I found a product called Tech Plastic that worked perfectly to fill the hole and keep the adhesive from getting into the shifter.
Now that the shifter is ready for installation you will need to determine the best way to route the E-Tube wire and hydraulic line through your base bar. With the Shiv it is necessary to route the E-Tube wire first as the cable exit hole in the base bar is not very large. On the particular Shiv in this project we ran into a little difficulty on one side of the base bar as there was quite a bit of leftover bladder material inside the base bar that made it difficult to pull the E-Tube wire through. Removing this leftover plastic added more than an extra hour to the assembly time.
Once the path through the base bar is clear I would suggest fishing a regular piece of cable housing through a couple times to make sure your e-tube and hydraulic line will pull through smoothly. Determining the best way to guide both the e-tube and hydraulic line through was a bit of a trial and error process. There was no guide channel in the base bar on this build so the hydraulic line could not be fed through on its own. When I tried to slip it through without a guide it would bottom out on the extension bolt hole and get stuck. After some experimentation I found a way to guide the hydraulic through without spilling any hydraulic fluid. I fashioned a guide line using a piece of brake cable end with a small section of a spoke threaded into one end. The spoke could then be slipped inside the end of the hydraulic line as it was pushed through and act as the guide. After installing the brakes and trimming the hydraulic lines all that was left to do was attach the shifters to the brakes. I have used used epoxy in the past to bound some seat collars onto some frames so was pretty confident this would work to bound the shifter and brake lever. After roughing up the brake surface to be bounded I mixed up the epoxy and covered the bounding surface of the brake lever. This became another learning process like cutting the shifter off the brake lever. The epoxy package says sets up in 5 min but the reality is it takes more like 10-15mins before the shifter isn't going to slide on the vertical surface of the brake lever. When I was ready to attach the second shifter I waited 5 mins after mixing the epoxy before applying it which result in a lot fewer readjustments of the shifter as the epoxy set up.
In the end we were very happy with the finished product.