shimano nexus 8 hub

So I'm wrapping up a build and need to figure out where to make adjustments for optimal gear ratio Here are the pertinent specs 26" wheels Huasheng 49cc 4 stroke tapered shaft with 4g belt drive tranny 20t - 100t pulleys(5 to 1) to final 9t sprocket 9t sprocket to 17t SICK Bike parts left...