[suicideneil]

"99% accurate", sometimes it doesnt hold true though, so its just a case of stocking up on spurs & pinions until you find a ratio that gives you the speed/torque you want & runs cool too. As for finding the right gear ratio, I wish there was, but even BrianG's mighty calculator can only provide the ratio needed for a certain speed on a certain voltage etc etc, it cant tell you if the motor/esc/batteries will run hot or not- just too many other variables (weight being the largest).