what is the advantage of mounting the hubbie in the swing arm rather than in the wheel.?
..gearing maybe ? .. but you seem to be close to 1:1 ratio ?
There are actually quite a few reasons:
The 28t at the motor 48t at the wheel reduction makes the 9C effectively running a 12" wheel so it will be able to climb anything. The lower gearing will also allow me to run the motor at 7-10kw buy going to high voltage, something not really possible without the gearing reduction. You can't just go to a higher turn count motor, because it can't handle the current. The only way is through higher rpms, just like the RC guys. It's a way for me to get the same power as my big hubs for about half the weight. The higher rpms (over 1krpm) will make the ventilation strategy even more effective, so the pretty extreme power will be relatively stress free for the motor, since 70A into a well ventilated 9x7 isn't a big deal.
Once I dial in the gearing I can have hill climbing, 40mph+, and regen braking in a light, low cost, and dependable build that doesn't sound like a cross between a drill and a vacuum cleaner.
14lbs mounted nearer the pivot point vs 24lbs in the wheel is a huge difference in terms of the suspension.
I wanted to find out first hand the noise level of a chain drive with large sprockets, and it's a non-issue. Now I have the potential for the benefits of a non-hub (changeable gearing, easy to change tire, multi-speed, etc.) without giving up any hubmotor advantages other than space savings and ease of installation.
A hub motor at high power enables a build that owns the Hanebrink as a real all terrain bike.