Selecting motor winding and voltage for 20" wheel

saucerful

1 mW
Joined
May 26, 2022
Messages
13
I have a 20" folding bike (Bike Friday) that I'd like to electrify with a Bafang G311 hub from Grin. They recommend a fast wind (10.5 rpm/V) for 20" wheels which they sell with a 36 V battery:

36 V * 10.5 rpm/V = 378 rpm

But I want to use a 48 V battery because I have a better source for those, already have a charger, etc. So I'm thinking I should get the standard wind:

48 V * 8.4 rpm/V = 403 rpm

Does this make sense? Or is it better to get the fast wind *and* 48 V. For what it's worth, I'm a pretty conservative ebike user, always pedaling, just trying to extend my range and sweat less going uphill. Thanks!
 
I have four 20' bikes, with Q100H motors, 260 rpm and 328 rpm. The slow winding on this motor is 210 rpm. While we don't ride these bikes much over 16 mph, they will approach 20 mph, which is higher than the 15.7 mph I calculate for 260 rpm on a 20" wheel. In fact, I prefer to run them on 48V, where they should exceed 20 mph, but I don't really do not know how much more. I like the 48V, because of the higher range, not the higher speed.

WIth 52T/11T gearing, I'm not fit enough to maintain the pedal cadence to use pedal assist at 20 mph, on a 20" wheel.

Anyway, I think I would prefer all of them were 328rpm. My one 328 rpm motor feels to have more punch.
 
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