It's not a tension adjustment
Use the length of that link to adjust the tilt of the pedals (rudder and brake) to your liking when the rudder is neutral.
When your feet are off the pedals, the tension is next to nothing. It'll be set by the weight of the pedals trying to swing as low as they can, and by the friction in the bearing blocks.
My airplane hasn't flown yet, but I've never heard anyone complain about the rudder cables slapping anything. I'd suggest you set the link length to "fit" the neutral pedal angle to your liking, and proceed to the next task.
Unless you go out of your way to pull the pedals towards you in flight, my guess is that the cables will not flail around much.