Lowest winding geared hub motors for 16" wheels?

[neithermovingnorstill]

Update: Turns out this won't work, as Gray Kard pointed out, the quad has single sided hubs, so hub motors won't work because they need support on both sides. I'll either have to run mid-drive, or choose another steed.

Hi,
I'm still investigating the possibility of E-converting a quatrike. I want to put the motors up front for various reasons.

Unfortunately, it has 16" wheels up front, so RPMs and winding become an issue, if I want to go over 15mph.
(15mph on 16" wheel= 310RPM)
Ideally, I'd use something small and light (XMUS, Bafang, Cute etc) but they are all about 310RPM or less as far as I can tell.

So I'm wondering: Which small geared hub motor has the highest RPM/lowest wind?

Yes, I realize that small wheels makes hub motors run cooler (allowing more wattage), and using two means they split the amps (run cooler), and higher voltage means lower amps/heat, so I could push them pretty hard...
but I want to be as efficient as possible, and since the small wheels / dual motor setup both cause an increase in torque, I think I should go with the lowest winding available.

 

[neptronix]

ever played with the ebikes.ca simulator?
There are some very very fast winds of the 9C/MXUS style motor that would be suitable.
A Crystalyte HS 48 motor would be good too.

You can pump an amazing amount of continuous power into a 16" wheel AND still have fantastic efficiency. Feel free to go buck wild!

Also, high speed windings of certain geared motors are not going to work too well, due to the high electrical RPM, which can choke standard eBike controllers, which are designed to go up to a few thousand RPMs, at the absolute most. A direct drive would be best in this situation for that reason.

 

[neithermovingnorstill]

Thanks Neptronix. I have tried the simulator, it's awesome for those motors, but the only geared motor on there is eZee, and it doesn't have any options for different windings. I ran the sim with the eZee, which is a bit bigger than the motors I'm considering, but as a guideline it confirms that I would need to get something with a lower than standard winding.

Maybe all the little motors are about the same RPM? Still, would be nice to know which has even a small edge, since it will multiply as I volt it up.

I did find a post of yours elsewhere, which was how I knew that small wheels can take so much juice, very good to know. I want to minimize watthours per mile, but it's still good to have power when you need it, so I will opt for 72v, and controllers with higher amps than I had planned.
I didn't know about "electrical RPM" limitations. I don't expect to ever be pushing it much past 3000 electrical RPM (~600 real RPM) which it sounds like you are saying won't burn out the controller. Does motor load effect that at all, or is it purely based on speed? (Since I would be splitting the workload between two motors)

 

[motomech]

Thanks Neptronix. I have tried the simulator, it's awesome for those motors, but the only geared motor on there is eZee, and it doesn't have any options for different windings. I ran it with the eZee, which is a bit bigger than the motors I'm considering.
The eZee would be fine, especially with high voltage, but I need something smaller, so I am still on the hunt for a small low winding geared motor.
AFAIK the lowest wind on the XMUS is still only 270RPM which would be less than 15mph in a 16" - ugh.
I don't know of any low wind Bafangs, or Cutes, so I may end up having to step up to a MAC, but that seems like overkill for a dual motor setup.

I did find your posts elsewhere, which was how I knew that small wheels can take so much juice, very good to know.
I didn't know about "electrical RPM" limitations. When I first read your comment about ebike controllers "only going up to a few thousand RPM", I thought, "I'd have worse problems than a burnt out controller, like wet pants and my hair going white all at once".
But then I realized you meant for geared motors, so the numbers are five times higher.
When you say a few, that means at least three, right? 3000 would enable the wheel to spin at 600, which would be great.
I wasn't planning on using a standard ebike controller, I was going to use a Kelly, since ebike stuff just seems pricey for the quality.

You are way off on your estimates.
For 36V mini-motors weighing under 3 Kg., there are three winds;
The slow winds have a no-load speed of 230 rpm @ 36V.
The fast winds have a no-load speed of 270 rpm @ 36V
And the MXUS, which splits the difference, 255 rpm @ 39V

I have tried the simulator, it's awesome for those motors, but the only geared motor on there is eZee, and it doesn't have any options for different windings.

Not correct, there is the "slow wind", the 26" wheel version and the "fast wind", the 20" wheel version, which is a very close sub. for the fast wind minis.
Using that motor in the in the sim., 16" wheel @ 48V/20A controller, yields a top speed around 20 mph. Two motors working together would raise the speed only slightly, to 21 mph.
The most cost effective way to do what you want to do would be a pair of Ananda 36V Q100's.
Adding current[Amps] would add very little to the top speed, at best a 1/2 mph, so you can save the added exspense of custom controllers and use those funds to increase Voltage if you need more speed.[I don't know what a Quatrike is, but 21 mph seems fast enough to me]

 

[neithermovingnorstill]

Hi, thanks Motomech, that sounds good.
I was editting my post as you wrote yours, to reduce my long windedness, too slow to avoid it being quoted though, heh.
I did wonder if the 20" was a lower wind, that makes sense.

Wow those Anandas are cheap, I hadn't checked them out, thanks. (I'll search the forums for reliability info)

~21 mph should be fine I guess, but with our urban traffic it often seems safer if you can go at least 30mph, since they tend to try to pass you otherwise, and around here that often leaves very little room for you, which is hazardous if they swerve for any unforseen reason.
I was just calling it a quatrike loosely, (quatracycle, quad bike etc), here is what I mean:
http://www.bentrideronline.com/?p=6335
As for how fast a quad can go safely, these things are really hard to tip over, I mean really hard. So I doubt 30 would be a problem. Above that, I'd have to test it going downhill before I made any assumptions.
Landspeed records for human powered vehicles are set in delta trikes going over 80mph, and delta trikes are the worse wheel configuration for tipping that I know of. Of course the racing variety are very low to the ground, but this quad's seat is low: 15".

 

[GrayKard]

Your main problem will be that standard hub motors are designed with axles on both sides and won't work with that quad.

Gary

 

[neithermovingnorstill]

D'oh!
Gray Kard, thank you so much for noticing that. Wow. Sorry everybody.
Even the rear wheels are single sided... ok, back to the drawing board. Bummer, I was so happy about the idea of 4wd.
You know what they say, when it sounds too good to be true...
I am so grateful to you for pointing that out, yowza.

There is a quad with two front forks, but I'm not sure about the design, would need to sit in one:

http://www.pedalcoupe.com/images/gallery/green_coupe.jpg
Here it is with a rider and baby on board: http://www.pedalcoupe.com/gallery/image6.html

Pretty much all other recumbent quads use single sided wheels. Maybe I have to go back to the delta trike setup... less stable, but they turn on a dime.