Michael, I don't see how the added bellcrank in your picture does anything to change the effective gear ratio. It seems like the added linkage would only contribute to overall slop (ouch).

The suggestion to use a bellcrank with a single linkage to the rudder defeats the purpose of using pull-pull. You might as well have one pushrod going back to the rudder. I will agree it provides a simple way to change the max deflection.

The best answer is from Tim. Control and servo horns can be different lengths. If the horns are in line with the pivot point, there will not be any slack, even at max deflection.

Tom