Originally Posted by icemilkcoffee

Exactly. Crossing once in front of, and once behind


Above. Although when I bought my wife's Bianchi bike, it came with Campy Ergo shifters, and the cable housings were routed in this type of double cross fashion, but under the downtube. It did work and it did keep the cables off the frame but the bends were a bit extreme. If your cable stops are further back and set low, under the downtube could be the best solution because the lower headset cup will keep the cables off the headtube.