If you need a smaller tube due to a thin airfoil, use soda straws, pull the housing off the end of the servo lead and the wires will slip right through. The problem though is if you need an extention, and there you will need to the 1/2" plus tube.

I've got to share an aileron servo lead nightmare that I aquired. I bought a 1.20 size pattern plane from a retired club member. The aileron servos were installed, but on a Y-harness. Not knowing what servos were used, or their condition, I decided to remove the old servos and put new ones in. The builder of the plane, a scratch built one, made things very dificult. He had cut rectrangle holes in the ribs, just big enough to clear the plug ends. Then the topping on the cake, he wrapped the servo leads with masking tape at each rib so the tape was through the rib, then he glued the tape to the ribs. I had to remove three bays of coverring on the bottom of the wing, then cut three access holes in the top sheeting to break out each of these glue messes. Then I had to enlarge the holes in the ribs to clear a plug not mater the orentation of the plug. I grit me teeth and curse at the unknown builder every time I look at the plane.

Don