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GM Magic Pie 500km test

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Hardcore:
wel my top speed of 43.3 was with wind so...

ggielen:
Your calculations are correct, good information! I plan to use 700c wheel size on mine with balloon tires adding to the total circumference, together with a more aerodynamically optimum design I'm targeting 45 km/hr, so these numbers really seem like I might get there. Bikemad is absolutely right about your top speed, you won't achieve that without some form of assistance, at top speed (rpm) the Pie is only putting out 64W, not even nearly enough to sustain that speed.

Range and ride time are pretty awesome too! And maybe you didn't gain weight, but maybe your bike got some extra parts, I remain diplomatic  :P

Hardcore:
haha nice, 700c is 28inch right,

305*60*0.002234= 40.8km/h on 305 rpm

45/0.002234/60=335

you need to get 335 rpm to go 45km/h

ggielen:
Yes, that's 28", but using Schwalbe Big Apple tires (ETRTO 60-622), the effective circumference of the wheel + tire will be 2350mm, so:
45/0.00235/60= 319 rpm

At 319 rpm, the Pie is still delivering about 530W, which I think will be sufficient to sustain the target speed for my lowracer trike. The effect of the increased tire size makes a small but noticeable difference, at least on paper  :P. Those tires are huge, but for rolling resistance they should actually be pretty good! They weigh a lot more, so acceleration will suffer of course. As an added benefit, they will act a bit like 'suspension', delivering a smoother ride, which at those speeds is definitely a plus.

And the 45km/hr target speed means I would theoretically be able to comply with the 'motorfiets' regulations (small motorcycle class, limited to 45). This won't be an electric bike, no pedals, it will be an EV: electric vehicle!

dajsino:

--- Quote from: Bikemad on November 24, 2009, 04:20:46 PM ---
Here's a rough guide to the data sheet figures:
Efficiency:     78.0% (Power Out/Power In)
Torque:         12.77 (N.m) (turning force needed to balance the applied load)
Motor Speed: 318 (r/min)   (actual wheel speed)
Current:        11.36 (A)  (current drawn by the motor)
Power Out:    425.27 (W) (energy produced)
Power In:      545.3 (W)   (energy consumed)

Alan
 


--- End quote ---

Yes, very good,

but I think that diagram "Motor performance curve" is missing something,
I wonder what is performance on width range rpm ,max load
somewhere should be that 1 kW power
maybe power and torque depending on rpm, starting with 0 rpm

in this case it is 425 W on 318 rpm, and it would be somewhere at the end of that diagram

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