Part 2 - Adding torque sensing bottom bracket https://www.youtube.com/watch?v=7Am96zl1S4E
Part 3 - Adding regen braking https://www.youtube.com/watch?v=4f-cK8RtMf4
This video shows the process of swapping out the controller in a turn-key ebike for an aftermarket motor controller. It's not a fun process, it's definitely not "plug and play", and in can in fact be a real pain-in-the-ass job. However, there are cases where in spite of that it still makes sense:
1) The bike is broken and no warranty support is available for replacement parts from the supplier, or
2) You have a legit understanding of DIY ebike stuff and need to modify the platform to have different performances and behaviors than the stock bike.
Here at Grin we're really solely focused on conversion kit retrofits and don't deal with factory ebikes at all. We have very little interest in attempting to interface to them. Never-the-less we get asked about this kind of work ALL THE TIME from people who have an ebike that doesn't live up to their expectations.
So we figured it was worth at least making an educational video to show what that process entails, and really more than anything to discourage people from getting in over their heads.
If you want to do this kind of stuff, you are on your own, no one will hold your hand through the process and you have to be prepared for nothing to work out.