I would not worry too much about it. Just make sure the rudder has no slack at center, but not too tight. Just tight enough to take up all the slack. The air loading will push that rudder and only one cable will be effective when it's deflected at all. You just don't want the tail wagging when the rudder is center and you are flying (happens when there is slack at center).
Also unless you have programmable servos, you can only use the trim or subtrim to center that rudder servo. Again, it's no big deal if you lose a degree of rudder throw in order to center the servo. Go fly it and let us know how it goes. I'm sure it'll be fine. If you have a 40%r then maybe you want to get more technical about it. In that case go to SWB's website and he has a lot of knowledge on that site.
ORIGINAL: strulag
Here it's deflected all the way. On the first one you can see how much the wire has moved towards the middle. On the last one both of them are very loose sine there's nothing acting on the rudder.
I also have a question...When I put the arm on the servo it's not completely perpendicular to the servo when the servo is centered. What do you do in that case? Do you just leave it like that and then hook the rudder at neutral (i get a little bit of binding on one side) or do you trim it to be perfectly perpendicular and then hook the rudder (I noticed in this case the rudder doesn't have same travel both ways) Thx...