Hi Maliba,
I just read your post about the chaos to route cable inside the frame. I'm actually thinking and listing all the parts to build this frame beginning of next year. I was thinking to build it with a shimano 105, because i want a double front rotor (can be discussed by everybody, but i prefer to climb on an easy way with a 34 or 36 rotor, instead of a solo 48 or 50)
And why a mecanical rather than electronic, 1st -> budget, 2nd -> i like "old schools" things 
Do you think it's possible to route it ?
Thank you
Good morning,
Let’s go step by step: according to Chris from Velobuild, the frame allows for a mechanical setup (I’ll comment more on that later).
If it were electronic, both SRAM and Shimano can be installed with a double chainring (standard).
Shimano electronic TT builds are quite tricky, because Shimano never produced components for a fully wireless 12-speed TT group. In other words, on the rear side of the bike you have all the Shimano 12v Di2 components (rear derailleur, front derailleur, and battery) — you set them up just like on a road bike. Then you need to add a third 12v electronic cable into the third port of the battery. This cable connects to a junction that converts 12v into 11v (the cables are very different). From that point on, everything will be wired with the older 11v standard cables.
At that junction, another 11v cable runs into a 4-port junction box (there are some models with 5 ports, but I used the 4-port because it’s much smaller). Out of the 4 ports, one will already be occupied by the cable coming from the battery that converted 12v into 11v. I then ran a single cable to each blip on the aerobar, and used a Y-cable for the brake levers. Here’s the catch: with this configuration I had a hard time fitting the stem into the fork and frame, because the Y-cable got in the way.
So, I routed the Y-cable to the brake levers inside the handlebar, plugged it into a junction (which I tucked inside the handlebar), and from there I ran just one long cable into the box. This way, inside my stem I ended up with 2 hydraulic hoses and 3 Di2 11v cables.
The build has to be done in reverse compared to the usual order where the handlebar is installed last. In fact, it’s much easier to assemble the handlebar first, already with the brake levers and all hydraulic/electronic cables installed, then slide everything into the stem, and finally into the fork/frame.
For a mechanical setup, you’ll need to route all the cables fully through everything. The stem will be your main challenge, but maybe if you follow the same process (assemble the handlebar first and then feed everything into the frame), it could be a bit easier. The stem is very narrow for so many cables, but it’s worth trying.
That’s why SRAM electronic ends up being the simplest and easiest solution — though still expensive.
Best regards,
