With the MR33 Drivetrain Checker, it is finally possible to measure and check the gear ratio and motor speed of RC model cars powered by 2-pole brushless motors.

Simply place the motor sensor on the motor, put the 7mm wrench on the wheel nut of a driven wheel, and step on the gas. 
Now just read the displayed value on the display, and the job is done in 5 seconds.
Simple and uncomplicated, for example, as part of the technical inspection before the run.