ThierryGTLTS This sounds really cool!
Actually in the current setup, Pacer supports a very simple assistive control based on the inputs of an accelerometer.
I've spent one weekend to implement it but I did not have time to dig into details.
For now the use case is like this:
You start pedaling. The accelerometer picks up the acceleration rate and tries to assist you by pushing power to the motor. As soon as you brake, the accelerometer detects the deceleration and tells Pacer to disengage the motor.
I think it's a bad ass method of controlling, but much more work and testing needs to be done in the way we process the inputs from the accelerometer. For now we only sample the x-axis. There's potential in getting the heading and other samples to get a more sophisticated algorithm. But time.. god damn time.. 
Alternatively Pacer supports a wired analog joystick or a radio Nunchuck that we made (using the NRF24 module).
I am planning to write some setup UI for pacer so that people can download, flash the nodemcu and setup Pacer (e.g. control type, max amps etc) from a web interface 
Maybe I will even get time to film some video tuts
Super excited about your project! Would really appreciate if you created a thread for the world's first project of a bike powered by Pacer in the Pacer Category.
Cheers!
TL;DR
You can use accelerometer input instead of pedal assist or use a wired/wireless analog joystick.
