I have just been studying photos of the Smart Pie and it has exactly five magnets between each pair of cover fixing holes.
As there are eight fixing holes, each spanning five magnets, this means there are forty magnets in total, which would produce twenty high/low hall sensor pulses for one complete revolution of the wheel.
Here are some more details for those who may be interested:
- The geared Mini Motor has 20 magnets and 18 slots
- The Smart Pie has 40 magnets and 36 slots
- The ProKit 901 has 46 magnets and 51 slots
- The Magic Pie Edge has 48 magnets and 51 slots
- The Magic Pie has 56 magnets and 63 slots
Alan