So after reading trough this.
I think I'm going to build a dual MAC 6 T 20" for my fast cargobike.
Bicycle in question: https://www.yubaeurope.com/en/bikes-add-ons/supermarche/85/supermarche
But the MAC 6t in a 20 inch rim at 48V is still just 41km/h And I would like to hit 45km/h reliably...