Low Speed, High Torque Hub Motor?

Electric Motors and Controllers
Daley   1 µW

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Low Speed, High Torque Hub Motor?

Post by Daley » Jun 08 2021 12:09pm

Hi guys.

I'm working on a project where I need a hub motor for very low speeds. The contraption should preferably use bicycle tires, for example 26". The speeds required are about 0-6 km/h. I have trouble finding a hub motor capable of accurately achieving these speeds. It also need sufficient torque to ensure a constant speed of the 70-80kg vehicle, regardless of incline or terrain (it will mostly be running on dirt). The motor can be either geared or direct drive, although direct is preferred. Does anyone know any motors that can do this job, or where I could go looking?

Speed: 0-6 km/h (0-3.7mph)
Suggested diameter: 26"
RPM: ca. 0-50 rpm
Vehicle weight: 70-80kg (154-176lbs)
Voltage: Any
Speed feedback: Yes


Thanks in advance for any and all help!

john61ct   100 GW

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Re: Low Speed, High Torque Hub Motor?

Post by john61ct » Jun 09 2021 12:51am

The problem without gearing is high amps at that low a voltage

you need controllers with heat sensors to stop before it melts

really big heavy ones will withstand the heat better

but look at gearing if you want to lighten the load.

Grin's simulator. . .

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APL   10 kW

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Re: Low Speed, High Torque Hub Motor?

Post by APL » Jun 09 2021 1:32pm

To be clear,.. it 'has' to be a in-wheel hub motor? Driving the wheel with an external motor and gearing could easily
achieve all those goals I would think. Just curious.

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neptronix   100 GW

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Re: Low Speed, High Torque Hub Motor?

Post by neptronix » Jun 09 2021 1:55pm

Any hub motor would struggle at those speeds if the load was very high, ie you are climbing a hill all day.

The magic pie and ASI hub motor would be the best choices here. They have the highest pole counts of any DD hub. Also using a smaller wheel ( 20" or less ) would increase the low end continuous torque capability.

This is also a very good application for a mid drive.
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spinningmagnets   100 GW

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Re: Low Speed, High Torque Hub Motor?

Post by spinningmagnets » Jun 09 2021 5:37pm

This is a spec that is far away from being common, so nobody stocks it.

Its easily done by a chain-drive and a non-hub motor.

Daley   1 µW

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Re: Low Speed, High Torque Hub Motor?

Post by Daley » Jun 09 2021 6:15pm

APL wrote:
Jun 09 2021 1:32pm
To be clear,.. it 'has' to be a in-wheel hub motor? Driving the wheel with an external motor and gearing could easily
achieve all those goals I would think. Just curious.
Well, it doesn't have to be a hub motor, but it would be very advantageous for the structure and reliability of the vehicle. It is not meant to climb hills all day, it's only required to keep a steady speed across a field, with potentially a little incline. And the operation is only a few minutes at a time, with long brakes in between.

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Re: Low Speed, High Torque Hub Motor?

Post by john61ct » Jun 09 2021 7:01pm


Daley wrote:It is not meant to climb hills all day, it's only required to keep a steady speed across a field, with potentially a little incline. And the operation is only a few minutes at a time, with long brakes in between.
Well that is a completely different use case than your OP.

Literally any DD hub will do, so go for less weight.

Select one with a top speed just above what you need, not too high

at the voltage pack you decide on

in order to maximize the torque at the from-stop lowest speeds.

Again, get to know the Grin simulator.

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Re: Low Speed, High Torque Hub Motor?

Post by john61ct » Jun 09 2021 7:05pm

Also check out Grin GMAC

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Re: Low Speed, High Torque Hub Motor?

Post by john61ct » Jun 09 2021 7:06pm


Vbruun   100 W

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Re: Low Speed, High Torque Hub Motor?

Post by Vbruun » Jun 10 2021 1:49am

DD is honestly not suited for this application. It will be needlessly heavy!

Just get a geared hubbie and call it a Day!

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Re: Low Speed, High Torque Hub Motor?

Post by SlowCo » Jun 10 2021 5:15am

Daley wrote:
Jun 08 2021 12:09pm
I'm working on a project where I need a hub motor for very low speeds. The contraption should preferably use bicycle tires, for example 26". The speeds required are about 0-6 km/h.
The low speed and high torque hub motor combination isn't a problem. But in a 26" bicycle wheel/tire is strange. As most of these applications used in a field use some sort of electric wheel barrow hub motor. So if the big bicycle wheel diameter isn't necessary then just use this: https://nl.aliexpress.com/item/32847757 ... web201603_


Wheel barrow hub motor wheel and tire.jpg
Wheel barrow hub motor wheel and tire.jpg (115.76 KiB) Viewed 405 times

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neptronix   100 GW

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Re: Low Speed, High Torque Hub Motor?

Post by neptronix » Jun 10 2021 3:05pm

Vbruun wrote:
Jun 10 2021 1:49am
DD is honestly not suited for this application. It will be needlessly heavy!

Just get a geared hubbie and call it a Day!
Those will burn up even quicker in the wrong situation because they also perform poorly at super low RPM.

let the ebikes.ca motor simulator be your guide to this.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Heavy duty Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

Xrhstos_Cy   10 µW

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Re: Low Speed, High Torque Hub Motor?

Post by Xrhstos_Cy » Jul 14 2021 5:11am

Hi, I have been looking around for similar specification but seems like with my required voltage and torque, I can't find anything suitable for me. any idea anyone?

My requirements are as follows:
Speed: 0-6 km/h (0-3.7mph)
Suggested diameter: 8-13"
Vehicle weight: 120-230kg
Voltage: 24V
Speed feedback: Encoder 1024ppr
Torque: up to 60Nm
Stall current: not more than 15A

john61ct   100 GW

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Re: Low Speed, High Torque Hub Motor?

Post by john61ct » Jul 14 2021 6:02pm

use gearing

Xrhstos_Cy   10 µW

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Re: Low Speed, High Torque Hub Motor?

Post by Xrhstos_Cy » Jul 15 2021 2:42am

I am looking for a brushless geared hub motor

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Re: Low Speed, High Torque Hub Motor?

Post by SlowCo » Jul 15 2021 7:04am

Xrhstos_Cy wrote:
Jul 15 2021 2:42am
I am looking for a brushless geared hub motor
Look at my post a little higher on this page. A double reduction geared hubmotor for a wheel barrow might work for you.

Xrhstos_Cy   10 µW

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Re: Low Speed, High Torque Hub Motor?

Post by Xrhstos_Cy » Jul 15 2021 7:11am

Had a look on those motors, as I am looking for 24V, the output torque is not enough for my application

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Re: Low Speed, High Torque Hub Motor?

Post by SlowCo » Jul 15 2021 7:32am

As you can't seem to be bothered explaining in more detail what you are building it is very hard to guess what is best for your application...
Probably a GMAC 12T motor in the smallest wheel/rim you can fit it into. But then you'd need a controller that will work with 24V and at high amps. Maybe a wheelchair worm-geared, brushed motor could work?

Xrhstos_Cy   10 µW

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Re: Low Speed, High Torque Hub Motor?

Post by Xrhstos_Cy » Jul 15 2021 8:14am

I have the controllers at 24V, the issue I have is that I am looking for a hub motor at 24V, high torque, and low speed. All these hub motors that are been used on scooters and bikes, all the 24V do not have high enough torque. I prefer it to be as one assembly too so this is a challenge too. I have been looking on brushless geared hub motors on Alibaba a lot but customer service are not the best to give accurate test curve of the motors etc.

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Re: Low Speed, High Torque Hub Motor?

Post by SlowCo » Jul 15 2021 2:46pm

Still no explanation on what you want to build, what kind of controllers (specs?) what usage, etc....

fatty   10 kW

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Re: Low Speed, High Torque Hub Motor?

Post by fatty » Jul 20 2021 12:38am

Xrhstos_Cy wrote:
Jul 14 2021 5:11am
Hi, I have been looking around for similar specification but seems like with my required voltage and torque, I can't find anything suitable for me. any idea anyone?

My requirements are as follows:
Speed: 0-6 km/h (0-3.7mph)
Suggested diameter: 8-13"
Vehicle weight: 120-230kg
Voltage: 24V
Speed feedback: Encoder 1024ppr
Torque: up to 60Nm
Stall current: not more than 15A
Ali won't help with application requirements. You need to convert this to technical specs:
from torque to Kv:
Kt = 60Nm / 15A = 4Nm/A
Kv = 15/2π = 2.39rpm/V

from Kv to rpm:
2.39rpm/V * 24V = 57rpm

from rpm to diameter:
6km/h = 6,000,000mm/h
circumference = 6,000,000mm/h / 57rpm*60 = 1744mm
diameter = C/π = 1744mm / π = 555mm = 22in

As you can see, common direct drive hubmotors are not valid for these types of applications.
This Alibaba category will get you closest.
Otherwise, as was mentioned: an external motor and gearing which decouples motor speed from vehicle speed would be ideal.

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Re: Low Speed, High Torque Hub Motor?

Post by fatty » Jul 20 2021 12:48am

Voltage is often easiest to adapt, so let's float voltage and fix wheel diameter to 13":

diameter 13" = 330mm
circumference = πD = π*330mm = 1037mm
rpm = 6,000,000mm/h / 1037mm*60 = 96rpm
96rpm / 2.39rpm/V = 40V

So a 48V system would bring these goals closer to reality

Xrhstos_Cy   10 µW

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Re: Low Speed, High Torque Hub Motor?

Post by Xrhstos_Cy » Jul 20 2021 2:19am

Thank you both for your replies!!

I started looking for 48V, to be honest. By calculations, it seems my application could work with the 48V. I tried to use 7.5A for each motor as this is the highest amps I will be using on each one and I reduced the speed to 1m/s which is around 3.5km/h as this is ideal for me too.

Now I will have to find a hub motor with 48V, but be able to have a rated torque around 5-7A.

I found this one: https://www.uumotor.com/15-inch-high-to ... coder.html

They told me they can do multiple different sizes which are good, but I am not sure if supply it with a maximum of 7A, what is the maximum torque I will get out of it?

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Re: Low Speed, High Torque Hub Motor?

Post by markz » Jul 20 2021 2:37am

Go with a mid drive motor and figure out what battery, controller and gearing you want.

Check out the motor simulator
https://ebikes.ca/tools/simulator.html

BBSHD
https://ebikes.ca/tools/simulator.html? ... &wheel=14i

Want more power to haul more weight?
https://www.cyclone-tw.com/product/1

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Re: Low Speed, High Torque Hub Motor?

Post by SlowCo » Jul 20 2021 4:42am

Xrhstos_Cy wrote:
Jul 20 2021 2:19am
I started looking for 48V, to be honest. By calculations, it seems my application could work with the 48V. I tried to use 7.5A for each motor as this is the highest amps I will be using on each one and I reduced the speed to 1m/s which is around 3.5km/h as this is ideal for me too.

Now I will have to find a hub motor with 48V, but be able to have a rated torque around 5-7A.

I found this one: https://www.uumotor.com/15-inch-high-to ... coder.html

They told me they can do multiple different sizes which are good, but I am not sure if supply it with a maximum of 7A, what is the maximum torque I will get out of it?

Very simply put: volts=speed, amps=torque
So why are you limiting yourself by only wanting to use a max. of 7.5A? More amps is more torque. The motor you linked to has a peak amp rating of 35A! It is the controller that feeds the brushless motor the amount of amps you program it to deliver (to it's designed maximum).
The way you are approaching it now is backwards. You shouldn't start with how many amps and volts you want to use.

So why not do it correctly and design your complete system in the best order?
1. Determine what you want to achieve (load, speed, wheel size, etc.);
2. Find a motor/wheel combo that can deliver that in your application (hills, weight, duration, etc.);
3. Find a matching controller;
4. Find a battery pack that can deliver the needed amps and has the capacity you need.

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