There are plenty of electric rear axles and controllers on the net.
But lets say you find a worthwhile on that operated in your speed range; how do you get the rear wheels to turn at the same rpm as the front ones?
Simple: (well simpler
)
E-bikes use a torque sensor in the crank that senses how much effort you are putting into pedaling.
You then dial in the amount of assistance you'd like on the controller.
So all one would need is similar torque sensors on the front axles and you're good to go with a fully automated system that would feel just like a more powerful, or more economical engine, depending on your mood.
It has regen too.
You would then have 3 modes:
Petrol: front.
Electric: rear.
Both: thx to the torque sensors.
There are a couple of very clever and industrious people on Endless Sphere that can help with the electronics.
The kind that build motors and controllers.
Some financial incentive would likely help though.