Note how a loop has been formed in the rear light cable at the bottom of the headstock with just sufficient slack to allow the handlebars to turn. It's zip-tied to the rear mech Bowden cable outer to keep it it place. Before your first ride in the dark, set the headlamp so it is pointing straight ahead. Then once it is dark go for a ride somewhere unlit and adjust it (downwards, typically) so it lights just enough of the way ahead for comfortable riding. Setting it high will blind the operators of oncoming vehicles, and make the illumination rather feeble (don't forget that the optics are designed to spread the light evenly). One advantage of the arrangement I have used on the Union headlamp is that I can tilt the light as required without tools.
