expo and rates all depend on the plane. But generally you try and keep the low rate at half the full. Its kinda trial and error. On my minnow I have small control surfaces and on low rates my ailerons dont move much but it still turns hard. I always leave my rudder on high rate with a 50% expo. I coulldnt turn taxi'ing the thing on low rates. But it is a tail dragger. My low rates are generally 30% expo. I had it higher when I first started flying the plane and it was just to mushy feeling. Im not even sure I have used the high rates on ailerons or rudder yet. And the are set at 75% travel/50%expo. My low rates are around 50% travel/30%expo. Oh and Im on a JR