Magnets need to be securely mounted and evenly spaced on the motor shaft and wheel, the suggested number is three on the motor shaft and 6 on the wheel. Increasing the number will give a higher resolution reading. The number of magnets used needs to be specified in the calibration.h file. Whilst not pretty, we have found electrical tape effective in securing magnets to the motor shaft, and have used 3D Printed mounts to secure magnets to the wheel.