I take it these bike beam/false crossbars are resting up under the stem? Just had a look at my bike and I'm pretty sure it would be squashing the cables if I tried using one?
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When you're using the crossbar the weight is split between the seat and stem, it's also rubber and I find the cables tend to not be at the point that supports the weight anyway.
Plus hydraulic hose is quite tough, I've not had any issues using one.