A fine video - good work!
As another chunky owner of a secondhand Gain I think I agreed with everything you said:
- fun to ride
- just enough power, but you still get a puff on, which is perfect exercise
- good quality build
- easy, simple to use button (there is a handlbar mounted controller too, if you really want it)
- I used the (owner's) app to check the miles too, before purchasing
- lacking power up really steep hills. I'm OK up to 1-in-8 (12.5%), but steeper than that is tough. But still better than without the assistance!
- spoke breakages (I had the wheels rebuilt to avoid this when I found them slack ergularly as you did - no breakages now)
- discs are fab. Mine are only mechanical but still way better than rims.
And yes, science.raven, the battery is removed from the frame via a hole down by the bottom bracket, but it's not really user-removable - it's a dealer operation since you have cables trailing up the tubes which need disconnecting/connecting afterwards).
That means you have to charge the battery whilst it's in the frame, which is a small downside compared to say a Fazua-based ebike where the battery can be removed.