Ok, so I scoped the hall rising-edge-to-rising-edge time at both minimum throttle and maximum throttle for 51.4V (present pack voltage on CrazyBike2, simpler and more comfortable than taking everything into the cold utility room to use the Sorenson).
I get 6.5ms for max throttle, and 140ms for minimum throttle.
If I multiply that times 20 magnets (40 total, 2 required for a full cycle), that's 121ms for a full rotation of the rotor. I forgot to measure the circumference of the rotor before I laid back down, so I'll have to do that another day.
But I know that the inside of the rotor at the magnets (where the halls are closest to) is about 171mm, maybe 172mm, because a 170mm disc brake rotor fits just about exactly in that space, with a tiny gap (see pic on a previous page). I'll go with 170mm because that's probably what the hall faces are at.
AFAICR, circumference = pi * (r*r), so that would be 3.1415 * (85*85), or 3.1415 * 7225 = 22697.3375, which should still be in mm. Apparently I must ahve the calculation wrong, because that comes out to 2.27meters, whcih is a bit over 74 feet! Off to google I go to find the *actual* formula for circumference.
Ok, so I was remembering the AREA formula, rather than circumference.

What I needed was instead diameter * pi,
or 170 * 3.1415 = 534.055mm, which sounds a lot more reasonable, as that is 21 inches. Still sounds too big, though it could be right. I guess I'll find out when I actually measure it with a tape measure.
So, assuming 21 inches is right, then now to figure out how to turn 21 inches and 121ms into an RPM. If it takes 121ms to move 21 inches, then let's see....60 seconds in a minute, divided by 0.121s, equals...wait. I don't need the circumference to figure out RPM; I just need to know how many times 0.121s fits into 60s. That would be 495.87, so it should be roughtly 496RPM?
Then knowing how large the circumference is, I can translate that into MPH, right? First, 496RPM * 3600 (seconds in an hour) = 29760RPH. Each rotation is 21 inches, (well, at the halls), and there are about 63360 inches in a mile, so 63360 / 21 is 3017. 29760RPH / 3017 is 9.86MPH. That's at a diameter of 170mm.
The original wheels on the powerchair would be 14" diameter, I think, so going back to diameter * pi, I get 43.98, close enough to 44" circumference. so 63360 / 44 = 1440. 29760RPH / 1440 = 20.67MPH. That's a pretty fast powerchair. :lol: That is of course an unloaded RPM ti's all based on, so even if we take that to an assumption of 80% of unloaded for a typical loaded cruising speed, a 14" wheel gets us 16.5MPH. Still pretty good, considering it's direct drive!
So, now, let's see what a 20", 24" and a 26" bike wheel would get:
20": 20 * 3.1415 = 62.83". 63360 / 62.83" = 1008.44. 29760RPH / 1008.44 = 29.51MPH! Even unloaded, that's fast! Loaded 80% speed would be 23.6MPH. Faster than I need already.
So a 24" would be even faster, and a 26" would probably be way way too fast.
I'm tempted now to not make a chain drive with it, but just figure out how to bolt a bicycle hub to it and drive it directly. :lol: I could use a disc brake wheel, and make a plate that connects the brake bolts to the rotor's outer mounting hole ring. There'd be no hub axle needed, so it can be left out--this motor would do all the rotation and support. Tempting, but all I have are front hubs for disc brake bolt-on style. I'd have no pedal drive with that. Still, for an experiment, it might be ok. Leave the front hubmotor on there to get home on if I blow the controller on the rear. Make a big plate and arm to bolt the motor to that then bolts to my cargo frame and bike frame or something. Have to draw it up and see if I have the stuff to make it from.
Alternately, I coudl botl it to the disc brake that's on the big Suzuki dirtbike wheel....but that wheel is very large, with a 19" (IIRC) diameter rim, plus at least 4-6" of tire on top of that. And I only have a big knobby on there, so it'd be likely a bumpy (or vibratey) ride. Still...the way that would look, outrageously overdone, is even more tempting. :lol:
As a side note, in trying to determine actual phase voltage at speed, to see what the kV might be:
At max throttle I can't see any PWM going on in the motor waveform, but it's hard to tell since I can't reliably trigger on anything when time is zoomed in far enough to see, and I can't scroll the view to see much more than a bit of the phase when zoomed in enough to really see what might be PWM slices.
I can clearly see the PWM even with one complete waveform on teh scope, when at say, half throttle, but it gets a lot harder to see above that. Might show up on camera better, but I didn't set it up to take a pic. Maybe do that another day.
One reason it's hard to see is that it "jiggles", because the rotor itself appears to be off-center somehow, though I am pretty sure there's no way to mount it off-center, with the way the hub of the shaft fits to the rotor itself. That's actually part of the sound you can hear in the previous motor vids, getting faster with the higher motor RPM.
It actually causes a change in speed during each rotation, so that like a planet in an elliptical orbit around the sun, it goes gradually faster for half of the cycle, then gradually slower. This is visible in teh hall cycle length, which changes approximately 0.1ms over a full rotation at full throttle (possibly less).
I'm not up to taking the rotor off and seeing if installing it aligned with different boltholes on the hub vs the rotor will fix it, but I might try that another day.