One thing that I noticed with the recent Di2 upgrade is that the D-Fly wireless unit is mounted on the right side seat stay, as recommended by Shimano. This unit can actually be mounted in between almost any two components, and it will still work to link up the Di2 system to a compatible ANT+ computer. The ANT+ computer that I am using is the Garmin Edge 510.
D-Fly wireless unit mounted on the right side seat stay. It is connected in between the rear derailleur and Junction B.
However, I find that this mounting position is not that neat, as it creates excess wiring around the rear drop out area that is messy. It would be best if this D-Fly unit can be relocated to a less conspicuous location.
I came across this blog from a bike mechanic that shows in detail how the D-Fly unit can be installed inside the head tube of a road bike. The details can be found at this link.
It would be very neat if the D-Fly can be mounted internally as shown, but it seems like a lot of work and I am not looking forward to removing the headset and fiddling around with internal wiring again.
The compromise would be to relocate the D-Fly to another external location on the bike, but in a less obvious location. Finally, I decided to mount the D-Fly around the bottom bracket area, similar to how it was set up on the Dahon Boardwalk and the Wheelsport Fantasy mini velo.
In this case, there is no space to mount the D-Fly unit behind the seat tube as there is very little clearance with the rear tire. After some trial and error, it was found that it is possible to mount the D-Fly unit in front of the seat tube, underneath the FD clamp. As this place is near the front derailleur and Junction B, it would be easy to run the wires along this area without being too messy.
Final location of the D-Fly unit, mounted on the seat tube, under the FD clamp.
In this configuration, the D-Fly wireless unit is connected in between the front derailleur and Junction B. It still works fine, which shows the flexibility of the E-Tube system for connecting all the Di2 components. With this arrangement, the D-Fly unit is nicely hidden along the seat tube, behind the crankset and under the tool bottle.
At the same time, the wiring at the rear derailleur area also becomes more tidy, as there is only a short section of wire that is visible. Due to the internal routing on this bike frame, the Di2 wire can run through the hollow right side chain stay, and straight into the rear derailleur.
Neat wiring at the Ultegra 6870 Di2 rear derailleur, with only a short section of Di2 wiring visible.
View of the full bike with the D-Fly unit hidden behind the crankset, and neat wiring at the rear derailleur area.
Full specifications of this Merida Scultura 5000 road bike. Weighs 7.3kg without pedals.