Okay lets see if I've learned anything.
Not sure I follow some of your figures. What is the 40 turns, is it turns per coil ( you say total turns).
I got the formulae from something I saw Hugh post. I had been thinking it was turns per coil, if that is in error please let me know. (the italics works, yay, thanks for the tip)
Your flux density figure is not realistic, that is about Br for neo in closed circuit, impossible in any air gap.
I was thinking this but couldn't find a good way to convert I was seeing 13700 gauss for these magnets and the conversion from gauss to Tesla was divide by 10000 hence the 1.37 originally.
I don't follow your tiny coil thickness but again you give no magnet length.
Not sure where I got it but somehow had the idea that the space between magnet faces on the rotors should be about the thickness of the magnet which are 1/4". That is 0.25". Take 1/4 of that, 0.0625", for the clearance between magnet face and coil (1/32" on either side of the coil) which leaves 0.1875" for the coil. If my reasoning is off again please kick and tell me so. The 1/32" clearance does seem to be tight to me but this was a 1st kick at the cat and one of those practical details I'm wanting to learn from the model.
Simplest way is to work the magnet at about 1/2 Br. for N48 that would be near 700mT.
For the formulae I make that 0.7T as the value for B?
If you can pedal indefinitely then about 80W would probably be the thermal limit with about #16 wire.
Another consideration I hadn't reached yet but was aware of, how does one figure the thermal limit of wire of a given size? Am I to take it you are suggesting using #16 wire
By the way, in case it isn't obvious I really do appreciate the time it takes for you guys to respond. I'm having a ball learning something completely outside my field.