Hi Ben.
Impressive work and diagrams. That is a VERY good idea about the bicycle hub for a small mill. I can't believe I never realized that! It was right under my nose.
I have been striving for exactly what you are striving for with a small "almost undetectable" (or;decoration looking) mini-mill that might do a few amps (max) on a 8'pole and/or on the roof. Except I think I'm going to try something like see thru (polycarbonate) round blades like a house 'box fan' moving high rpm. (probably only 2.5' diam)
The great thing is round blades shouldn't make any noise when going fast and It can be a downwind mill which looks better to me.
Those tiny low friction bearings in a bicycle wheel hub are perfect. Looks like I need to find a reasonable bicycle repair shop fast. Not many do that anymore around here though. I can't even find a simple 2" sproket anywhere!
I have regrettably screwed up and reduced the output of most of my projects with high resistance. I now view resistance like my 'Darth Vader'.
Perhaps It would be better if you could go with more magnet/poles,(7" dual steel rotors) then you could go with bigger ga. wire in the coils (less turns) and get more amps in every wind speed. The one I am making has the 7.25" diam dual steel rotors (like 1/8" thick circular saw blades at 'BIG Lots') So I hope to put 12 mags on each rotor for a normal 12/9 (9 coils) 3-phase set-up.
Except I am going for the higher voltage 24v battery system for much less line loss since it will be 75-100 feet away.
I'm not sure I can do it yet though. I think It will. It is interesting to try.
My mags are 1" diam (N42) 1/4" thick. I'm going for a 1/4" thick stator (3/8" mag to mag air gap) with 20 awg wire/ 80 turns per coil.
Hopefully, 24v cut-in around 400-500rpm??
You are doing a very interesting project there. I hope it goes well and look forward to what you make. You do good work. Thanks for sharing the idea about the bike hub. It helps my project a lot.