Originally Posted by
Iride01
Yes that is somewhat true. And for most "casual" DIYer's I can see where that would nix it for them. However "dedicated and determined" DIYer's even way back in the vintage days were putting cables for shifters and brakes inside frames that didn't come stock with internal routing.
Di2 wires come in all lengths, so with the correct mounting externally, it can look just as good as the external cable housings that are already on it. Di2 front and rear DR's and any of the components can even share the same wire run with y's or splits at appropriate places as they rely on signaling and not just on/off voltage.
Though off the top of my head, the only issue will be if Di2 ever had a cable pulled STI for the bakes. I thought it did, but without looking it up, I can't be certain.
Maybe SRAM eTap wireless is the answer for a frame not designed for internal cable routing? Doesn't that system remove the wiring between the brifters and the derailleurs, and removes the wiring between the seatpost battery and the DR's, since each brifter and DR has its own battery and the signals between brifters and DR's are fully wireless?