[tzjin]

Our team typically uses the free speed to do most of our calculations. Truth is, you will probably be spinning quite fast since the wheels are under no load, but when the ball comes through, the impact will be pretty much impossible to calculate. Just test it.

But yes. Don't gear up those motors. I hear good things about Andymark's 3.67:1 gearbox paired up with six-inch wheels, though 8-inch may work too. You will most likely burn out those motors even if you direct drive them, and the wheels will take a very long time to speed up, and regain speed once a ball passes through.