Does this sound correct?

[Blunderbuss]

I have the chance of getting a 8fun motor with the following details and would appreciate someone marking my homework .

Rear Hub 8fun on a 26” rim – the code on the motor is:
CST 36V 500W
1606 0529-6

So using the data from this chart I am presuming it is a code 16 (https://endless-sphere.com/forums/viewtopic.php?f=2&t=43106) and it will be attached to my 48V battery giving 255rpm.

26” wheel = 66cm

66cm x 3.141 = 207.5cm circumference

(207.5cm x 255rpm)/100 = 529 meters per min

529 M/min = 32 Km/h

32Km/h = 20MPH

I appreciate these are maximums, but as someone who averages 10 to 15 mph off road I think this sounds a good match (if I have got my sums right of course!), any opinions would be welcome.

 

[Deleted member 4366]

They weren't marked with a speed code like the BPM. All the ones I had were 270 rpm at 36v.

 

[Blunderbuss]

Thank you d8veh, I work that out to be about 27MPH max which is faster than I was expecting with the geared hub, I thought I would be sacrificing more top end to get the benefit of better power at the low end.

 

[Deleted member 4366]

Thank you d8veh, I work that out to be about 27MPH max which is faster than I was expecting with the geared hub, I thought I would be sacrificing more top end to get the benefit of better power at the low end.

201 rpm with a 26" wheel is 15 mph. 270 rpm is around 20 mph. You can add another 10% for the battery being around 40v most of the time.

If you run a 36v motor 270 rpm motor at 48v, you'll get a max rpm of 328 rpm, which is around 28 mph. Real world speed on the road will be about 24mph because the back emf will increasingly cut down the current above that speed, so power ramps down.

Those speeds are for a 26" wheel. A 700C wheel will be proportionally faster, but the Bafang CST motor is a bit too heavy and powerful for one of them. I think that the Q128C would be better for that sort of wheel.

 

[Blunderbuss]

201 rpm with a 26" wheel is 15 mph. 270 rpm is around 20 mph. You can add another 10% for the battery being around 40v most of the time.

If you run a 36v motor 270 rpm motor at 48v, you'll get a max rpm of 328 rpm, which is around 28 mph. Real world speed on the road will be about 24mph because the back emf will increasingly cut down the current above that speed, so power ramps down.

Those speeds are for a 26" wheel. A 700C wheel will be proportionally faster, but the Bafang CST motor is a bit too heavy and powerful for one of them. I think that the Q128C would be better for that sort of wheel.

Thanks again for that, as well as the better torque i can see how much smaller the Bafang looks compared to the Direct Drive, it looks only as big as the brake disc (160mm) whereas the DD is "huge"!