If you
want to keep the bicycle as a bicycle, with
some assist... I would get a pressure sensor type of system that controls the amount of assist, NOT, a rotation sensor type of E-Assist... and... Certainly NOT, anything with a throttle... JMO...
Also, something that would work as when you want to ride the bicycle
without any assist, weight, and the drag of the electric motor can make it really hard to ride an E-Bike without it being turned on... again... JMO riding my E-assist bicycle that I can ride without the motor on and not feel like some,
that say it was almost impossible to ride their E-Bike without it being turned on, (dead battery)...