I'm just waiting for Merlin to confirm they're hollow. They have the holes in the bar ends and internal cabling for the brake lines. I've seen a few bikes built with them and everything seems to be hidden nicely and the di2 routed neatly...
There is no hole near the stem or shifters though, so the routing will have to allow for escaping out the holes near the bar ends and routing in the huge cable runs under the bars.
That's fine. Only thing that's needed is to be able to pass a cable all the way through from one bar end to the other. The attached pic I've just been sent shows that it can be done on these bars!
Another potential option are these https://www.merlincycles.com/deda-superzero-carbon-aero-road-bike-handlebars-97174.html?
I'm just waiting for Merlin to confirm they're hollow. They have the holes in the bar ends and internal cabling for the brake lines. I've seen a few bikes built with them and everything seems to be hidden nicely and the di2 routed neatly...