I have students doing a robotic car design challenge in class. Some of my students are doing high speed ratios and even compound gearing to make those ratios higher for speed. They work well when you're holding the car but don't move once they're set on the ground. Could it be because there's so little torque? Wondering if anyone has done something similar and has any suggestions on what to do with programming and whatnot to make these high speed ratios work on the ground.