We were wrong about the ease of exchanging the robot’s drivetrain motors from Andy Mark 40:1 gear ratio to 20:1. The 20:1 motors were longer and would not fit into the space available. So, we geared the 40:1 motor with 10-tooth sprockets on the wheels and 20-tooth sprockets on the motor. This gives us 20 tooth/10 tooth = 2 times the speed compared to using the previously installed 15-tooth motors and wheel sprockets.