AiM devices can measure the wheel speed using a non-contact sensor that needs a metallic trigger to pass in front of it.
To better detect the speed AiM strongly recommends to use an optional rear axle collar that already
includes a magnet. Different diameter collars are available.
Installation
Install the sensor using a bracket;
install the collar on the kart rear axle and ensure the distance between the sensor and the collar
magnet is between 8 and 20 mm
connect the sensor to AiM device.