Riddle me this, Batman: I have rear wheel hub motor from the original Swytch bike indigogo campaign. 36v,22a controller. It was on a 700c wheel and I could regularly get up to 26-28mph on max PAS on a flat. I had the motor re-laced into a 20" wheel and can barely get above 16-17mph. After looking closely at the motor, it seems likes it's a Shengyi DGW22, which is nearly identical to the sx2 from GRIN, standard wind. 1/2
@Karstan assuming actual 28in and 20in wheel diameter (or measure a few rotations of roll-out to account for your actual weight and tire/ pressure etc) then you should see 20/28ths the speed, modulo the higher wind resistance above 20mph. What is the simulator saying you should get? Did something change in the motor/wiring/connection / controller? Speed measurement method?
If I simulate with the Shengyi standard wind, I get 22mph for the 700c wheels and 17mph for the 20". If I simulate with the Shengyi fast wind, I get 24mph and 21.5mph respectively.
@enobacon I think I'm going to have to take the edgerunner out for spin (it's a been awhile) to get some more tests out of it because this isn't making sense. I distinctly remember easily getting above 25mph when I had the 700c wheel but struggling to get to 18mph on a downhill on the Edgerunner.
@enobacon Yeah, except I was easily getting 26-28mph with 700c wheels. And this was the "30mph, 50mile range" kit from the Swytch's original Indigogo campaign. Something isn't adding up.
Pretty good! But this was a weird one. Atypical to the regular Swytch kit since it was a rear wheel motor. They only offered it that one time. I'm guessing they lost $$ on the rear wheel kits because it was a screaming good deal.
Dunno about the field weakening stuff.
The 30mph was, I assume, under perfect operating conditions with a light road bike in an aerodynamic tuck. I had it on a more of an urban commuter type build (though still fairly light weight).
@driusan@enobacon Yeah, I updated the wheel size settings. See my other comment about the Swytch kit though. This was not a typical kit. Rear wheel with a bigger motor than their usual offerings.
@Karstan@driusan whatpressureyourunning, rolling resistance etc? You could dial all of those parameters into the motor simulator to match, but I would expect wind resistance between 20-28mph to be significant vs at 18-20mph, tuck and lycra or not. All other things being unchanged (hard to match the tire performance when the rim size is different though), you should get 20/28ths of the prior speed. Sounds like 10% higher losses though?
@enobacon Yeah, too high for tire variation and riding position to account for. I'm essentially trying to dial in exactly what this motor's specs are so I can decide what to do with it going forward.
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