Are you talking about the outer struts that are 3/4 of the way out on the wing? If so, they aren't really necessary to fly the plane. But they look cool!

If you're talking about the top of the inner cabane, when you place the wire frame on top of the ply cabane, the instructions show where to place that, and I lined up the front of the wing to just enough of that to clear the rubber bands.

On the outer struts, I think it was a "by the look of it", and the way it fit the top of the bottom wing curvature. I think it was back like an inch on the bottom of the top wing, and maybe like halfway back on the top of the bottom wing. I also leaned mine 'outbound' on the top wing, giving them a bit of a slant toward the tip. But, that's me... I made sure the little pushrod piece that holds it on go almost all the way through the wings, because they will pop off in the air if you bounce it around alot.

phil in austin