# 15" car hub motor $799



## Jason Lattimer (Dec 27, 2008)

Hey I was wondering, does anybody know anything about this motor. 

It is on the Kelly controller webpage. States it works with a 15" Buick wheel, has disk brakes and is good for 160kph.http://kellycontroller.com/car-hub-motor-72v-7kw-p-711.html

According to the website, it is good for 72 volts and the controller they suggest pairing with it is good for 400 amps for 1 minute and 200 amps continuously.
Should be good for 38 horsepower for 1 minute if I did my math right.


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## Jason Lattimer (Dec 27, 2008)

O.K pic didn't work so here goes again.


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## major (Apr 4, 2008)

Jason Lattimer said:


> http://kellycontroller.com/car-hub-motor-72v-7kw-p-711.html
> 
> According to the website, it is good for 72 volts and the controller they suggest pairing with it is good for 400 amps for 1 minute and 200 amps continuously.
> Should be good for 38 horsepower for 1 minute if I did my math right.


Those look like about 18 AWG phase leads, maybe 16. What'd you think? 200 Amps???? Motor spec says 7 kW. I'm thinking maybe 1.5 kW continuous, about 2 hp. But it fits a Buick wheel


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## Jason Lattimer (Dec 27, 2008)

Yes I know, it is confusing to say the least. Here is a kit that they sell. For 799 dollars if it works it might work for a low weight reverse trike.








96V/120V Dual Car Hub Motor Kit 

Click to enlarge 
Click to enlarge 
Price: $3,899.00 









*Weight :* 166.00 lbs
* In stock * 

Provide free disc brake.

The top speed can arrive at 160km/hr with 96V system.

The kit can work for 96V Lead Acid Batteries or 96V Lithium Batteries.
Please note the kit can work with 120V Lead Acid Batteries, but with 120V Lithium Batteries it may report overvoltage fault.

*  For 96V System:*
KBL12401I(120V 400A Regen)*2
The assembly*1
Car Hub Motor(12-inch)*2
F9607-96V/7A Charger (110VAC Input)*1
Throttle*1
PC RS232 cable*1
USB to RS232 Converter*1
Control box*1
Kelly 96Volt Charge Meter*1
Ampere meter*1

Can do regenerative braking.
Best for car.
Can upgrade to HWC4B Series 96V/12A  smart charger with $199.
Please note charger input voltage, 110VAC or 220VAC.
110VAC Input: F9607-96V/7A Charger 
220VAC Input: F9607-96V/7A Charger 


*  Can upgrade to 120V System with paying price difference $200.*
Upgrade the following items:
HWC4B Series 120V/8A Charger (110VAC Input)*1
Kelly 120Volt Charge Meter*1


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## dexion (Aug 22, 2009)

Having destroyed and ripped apart a 6kw hub motor (on my lithium evd.) Let me explain the weakness of these motors.

If you look closely you will see all the wiring going into the axle of the hub. At that point is where the wires melt together (on the cheaper chinese hub motors I worked with.) There is just no good way to cool the wires at that point. I melted my hall sensor wiring together at that point with 700 lbs (bike and 2 riders) going up hill at 40mph in 80F weather. Its a fairly easy fix. One must disasemble the motor and replace the wiring with something much higher rated (insulation) than what is there. But ultimately (unless you shut down the motor when it gets hot) it may happen again and again. 

I would love to get hub motors it would simplify any conversion but it looks like they all have this weekness. However, Jack R is getting a set from Chry for a smartcar conversion. So perhaps we will see better quality at work and the problem will be solved. 

The above motor looks like the one that a place here in Ann arbor uses for their scooter. They replace the hall sensor wires with high temp ones before they even put it on the bike. That takes care of the problem but their bikes are 700lbs with 2 riders and the bike itself. Not 2000 lbs. 

There is no reason aside from cooling that a hub motor wouldnt work in your application as long as you understand its failure mode and its for a light weight car. Acceleration however will be marginal with 2 of them now if you did 4...

But ultimately a mars or D&D even would work for light weight cars and an altrex controller. But it really depends on your application.


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## Jason Lattimer (Dec 27, 2008)

Thanks for the input. I think that the best thing to do would be to use a small motor separate from the wheel in case the motor needs to be made bigger. It looks like a wonderful idea from a packaging perspective, but when you tell me of the problems inherent in the design it looks less appealing.


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## AussieRav4 (Jul 16, 2012)

I would like to know more on your thoughts on this hub motor.
I'm toying with the idea of using these to power a Toyota Rav4 conversion. 

I do agree with dexion on the cooling aspect of the cables. this is a particular concern of mine as i live in Australia where the summers can be good and hot. 

knowing that my car might be approximately 1200kg [2650 pounds] I'm now wondering if my thought on the use of these motors might be a little optimistic. I was toying with buying 4 of them for my car to keep the whole AWD system going. 

I'm still in research mode on my plans so I'm looking for the best information sources i can find.


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## Salty9 (Jul 13, 2009)

Looks similar to: http://electrichubcap.creativesystemdesigns.com/weel.html


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## PStechPaul (May 1, 2012)

I looked at their test curve data and I think there is something wrong with the readings - or the motor itself.










I added the column with the product of volts and amps which should equal watts, but it's a bit off. However what really stands out is the very low efficiency at low torque output. There are fixed losses of more than 1000W at all loads at nominal RPM. I'm not that familiar with BLDCs but using a 2HP 3 phase motor, the total power used by the DC-DC converter, the VFD, and the motor itself, is about 5 amps at 24V or 120 watts. For a 7kW 10HP motor it should be no more than 5 times that, or 600W. 

I realize that it may be an unusual condition to run the motor at 1300 RPM under such low torque conditions, but even the best efficiency of about 83% is not impressive. And $800 seems a lot to pay for a 10HP motor.


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## jeremyjs (Sep 22, 2010)

It seems like many have tried high powered hub motors, and to date, all have failed. The problem is, everyone who's tried it seems to simply abandon it without giving the reason, so people/companies keep trying. I have to ask. For what. If it's such an issue keep it inboard and connect it to the wheel with an axle.

One theory I've heard is that the motor bearings simply can't take that kind of load, but, like I've said, all that have tried and failed have been curiously quiet about why. So no one, but those that have tried it, seem to know the actual answer.


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## AussieRav4 (Jul 16, 2012)

I will agree with you that the price is high.
I am so new to the whole EV conversion goal that i don't have a full understanding of what you just said. 

all i can really work out is that because there are numbers that don't add up there may be some over optimistic claims made by the kelly company regarding these motors regarding their use up to and including 160km/h [even i think that figure is a dream from this motor]. I just want to have the car as a way of getting around and going shopping/work and still be able to use it as a semi family car on a weekend or for putting a MTB bike on the roof and going for a ride in the mountains. [refer to my post in the conversion forum, http://www.diyelectriccar.com/forums/showthread.php/planning-toyota-rav4-aca20r-short-wheelbase-76422.html

the hard part is that i would like to try and convert a short wheelbase Rav4 to a EV and keep the AWD system. the idea of a hub motor seemed logical. and the idea of efficiency of the motors has yet to really enter my thinking process. 

but if there are concerns with these motors it might be best to look at a more conventional EV conversion.


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## PStechPaul (May 1, 2012)

The maximum torque of the hub motor is 78 N-m or 57 lb-ft. If the tire is 24" diameter the amount of force it can exert is 57 lb. Assume you have four of these motors you will have a force of 228 lb. If your vehicle is 2280 lb, it would be just barely enough for a 10% grade.

The speed is determined by the circumference of the tire, about 6.3 feet, so at 1300 RPM that's 8190 ft/min or 93 MPH. So 160 kM/hr is believable. But you really need more torque. 

[edit] I thought these motors were designed to connect to the wheel through a CV joint. But that was the WEEL motor. If that's the case you don't need a hub motor.

The "hubcap motor" project from Turquoise is interesting. I also had an idea for a bolt-on hybrid conversion kit, but adding the weight (and size) of a motor on the outside of the wheel may adversely affect the driving characteristics.

Good luck!


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## AussieRav4 (Jul 16, 2012)

Cheers. 
The Rav4 is about 2600 pounds [i think, it might be less as i can't confirm the figures]. with this figure in mind the grade is now a good thinking point.

might be worth looking for a new plan of action regarding transmission conversion list. who knows, it might be worth looking into your idea of preserving the CV joints and attaching a motor to each of them. who knows.

thanks for your help.


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## Tedktis (Jan 20, 2012)

Without a transmission your going to need more torque, which = more $. I don't think the hub motors can withstand the constant 'bumps' in the road or rain to be reliable. There is also unsprung weight to consider. I'd stick with the transmission and AWD and bolt one motor on. Unless you have the resources and time, maybe you'll find the solution? Good luck.


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## AussieRav4 (Jul 16, 2012)

I agree.
its time to get technical and work out the best electric motor to buy and find/pay someone to make a mounting plate and adaptors for my Rav4. it will let me keep a mechanical reverse gear and potentially have enough grunt to get up hills. 

i will need to look at adapting the conversion by gdirwin to suit my car and local conditions. both cars are more or less the same. its just his was the full size Rav4 and i have the short wheelbase. 

just need to think about the coupling and the touque convertor. 

I was thinking about the rain and the unsprung weight earlier today. I agree with the idea. I still want to have some degree of ruggedness to the car. 
aww well back to plan A.


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## ruckus (Apr 15, 2009)

The most powerful (claimed) hub motor I have found is the Keguang KG315. They claim 20kw and 380nm, 250v and 1800rpm. 

Edit: here is link: http://www.evmotor.net/kg/eng/ProductShow.asp?ID=95

Making the giant assumption it actually works as advertised, I don't see how to mount it to a regular car spindle since they are all male (outies). What am I missing here? Has anybody got this to mount up?

The other issue is the need for multiple motors and controllers. That kinda defeats any price/simplicity advantage.

If it could be done though, the additional weight and space freed up by ditching the tranny/drivelines is HUGE. Think of all that battery space...

Cheers


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## mk4gti (May 6, 2011)

ruckus said:


> I don't see how to mount it to a regular car spindle since they are all male (outies). What am I missing here? Has anybody got this to mount up?


I'd like to know as well. The cars I worked on in my lifetime have solid (not hollow) drive shafts at the front hub and solid spindles at the rear wheels. There wouldn't be place to route the wires.

It looks like they mount the motor right on the brake rotor, which would make the wheel poke. Teenagers seem to enjoy this style - I think it looks goofy.

As someone else mentioned, these wires are way too small to power a RAV-4 for example, even at the four wheels.


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## Tedktis (Jan 20, 2012)

AussieRav4 said:


> I agree.
> its time to get technical and work out the best electric motor to buy and find/pay someone to make a mounting plate and adaptors for my Rav4. it will let me keep a mechanical reverse gear and potentially have enough grunt to get up hills.
> 
> i will need to look at adapting the conversion by gdirwin to suit my car and local conditions. both cars are more or less the same. its just his was the full size Rav4 and i have the short wheelbase.
> ...


Nothing wrong with thinking outside the box, you may very well have something. I just hate to see ppl get part way into a build and bail. Although that's where I get good prices on components.


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## AussieRav4 (Jul 16, 2012)

Ruckus,
thank you for helping with this additional product. it didn't come up in any of my searches.
it looks like a good piece of kit. its something that i would consider. I also guessing its EV weight considerations would be minimised by having 4 of these in the car.


mk4gti,
your right about mounting them in a car but I'm guessing something could be fabricated. If I'm not wrong i seem to remember my dads land cruiser having a shaft housing that was hollow. at a guess this would be a place to install the motors into and still provide a place to route the wires.?
its not possible in my rav4 and it still leaves a question as to how to mount the fronts so they steer but I'm guessing something could be made.

I have seen these hubs as a style in mock-ups on various vehicles in shows and I've always thought there is great promise in these hubs to convert the existing fleet or to provide for better storage of the power source. 

--

the thought as to how much weight would be removed from the car with all its ICE and transmission removed is a good thought but if 140kg of motors are installed + controlling gear + mechanical/electrical augmentation of existing control mechanisms + batteries I'm wondering is the advantage is neutralised. 

don't get me wrong, this is project of mine is to be very carefully thought out and will be my version of building a lotus 7. [now theres a thought - an EV lotus 7 replica powered in the rear by 2 in hub motors on a "live axel" suspension setup].


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## ruckus (Apr 15, 2009)

Well, the idea of hub motors is a good one, but it would be best used on an 'experimental' platform which is light-weight and small. I wouldn't go getting all fired up and try to convert a daily driver suv to hub motors without a test vehicle. 

I am not one to follow the mainstream, but hub motors are the lunatic fringe.

Please be careful.


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## Salty9 (Jul 13, 2009)

Don't know the price but 4 of these might work: http://www.enertrac.net/


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## ruckus (Apr 15, 2009)

Salty9 said:


> Don't know the price but 4 of these might work: http://www.enertrac.net/


$1,295.00 -- for ONE. 

sooo, about $5180 per 'moto' car. This doesn't include the 4 controllers...


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## midget (Aug 19, 2012)

Good day,
I'm glad to see a somewhat recent exchange about hub motors. I have also been trying to research creating an EV using 72V 7kW hub motors from Kelly Controls. The donor I had in mind would be an MG Midget, and it would be just the rear wheels that would recieve the motors. Each hub motor weighs about 60 pounds, but some of the items that would be removed would be the transmission, differential, driveshaft, axle shafts, engine, gas tank, etc. I'm still trying to calculate how much total weight and sprung/unsprung weight that will eliminate. The donor vehicle would start at around 1620 lbs before stripping it down. For batteries, I've been looking at GBS Lithium 72V 60Ah pack (from electricmotorsport.com) with a weight addition of 122 lbs.

So my point is, am I setting myself up for disappointment if I go that route? Or will I have the potential to realize my modest goals of a 20 mile range with that set up?


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## AussieRav4 (Jul 16, 2012)

gday midget,
i know i'm not the best person to talk to on this one and i will be corrected later. If you see my earlier questions on the hub motors then you will even see me back away from their use. As a concept they seem really, really good and lots of potential. 
In my line of work its as soon as someone says "but" you listen. they seem really good but they have other issues such as the points that were spoken about earlier. 

i still want to build an electric car but im wanting to get a car i can work with first. i see car being something i will take a huge amount of pride in and potentially use as a rebuild, educational tool and general runabout. it means i want it to be safe and reliable and not bite me or students in the ass.

The issues that are part of a hub motor concern me enough to plan for a far smaller car to convert [eg an old mini or a 1960-1980 VW bug] and use it as an experiment.


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## midget (Aug 19, 2012)

I think the MG qualifies as lightweight and small. Here's the part of the research that is giving me troubles:
I know my theoretical inputs, such as...
Two 72V 7kW hub motors, one on each rear wheel.
72V battery with 60Ahr (4.61 KW/hr capacity) 600 CCA and 61.8 max HP.
Donor vehicle of approximately 1500 pounds converted weight.
Access to machine shop to build custom hub axle supports.
The rewiring of the hub motor leads before assembly doesn't sound too intimidating.

But what I am having trouble figuring out is, will it be able to start from a dead stop. The "calculators" I have seen so far all make the assumption that the motor will be run through a transmission. I've tried looking for electric golf cart values to see how they rate in comparison by "scaling" up weight, voltage, power. But I can't find enough information to begin calculations.

I have the battery "HP", but I don't have the motor HP. Can that be calcuted by looking at given parameters or does it have to be tested in real world contitions? 

So far nothing has been purchased. And I certainly don't want to be throwing money down the drain. The reason for not leaning toward the traditional configuration is budetary. The state of IL offers a $4000 tax rebate for conversions (80% of $5000 max) so the $6000-$7000 budget range plus donor vehicle cost is what I'm targeting.

Too bad LUNATIC FRINDGE won't fit on the license plate!


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## PStechPaul (May 1, 2012)

As for starting from a standstill, that is all about torque. HP only is defined for a certain RPM. But you can estimate the torque, by using the formula:
T = HP * 5252 / RPM​For a hub motor, 1000 RPM is pretty much top speed, so if you have 14 kW or about 20 HP, your torque will be about 105 lb-ft.

If your wheel is 24" diameter, the thrust will be 105 lb. If your vehicle has a total weight of 2000 lb including driver, batteries, motor, chassis, etc, the vehicle will be able to just barely climb a 5% grade. Or on a flat surface, you will be able accelerate at 0.05G.

If the HP rating you give is nominal, you might be able to get more torque for short periods of time, but you won't be able to climb most hills. You need even more torque to overcome wind and rolling resistance if you want to achieve even minimal highway speeds.

There are many on-line calculators that can help with things like this. I made one you can use:
http://www.enginuitysystems.com/EVCalculator.htm


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## midget (Aug 19, 2012)

Thanks for information.
I am coming from a position of ignorance, so please don't think of my questions as confrontational.

Now that I have some values, can I ask how to interpret them?
From my research I've read that the HP value of an Internal Combustion Engine is not the same as the HP value of an electric motor. An electric motor can have a value 10% that of an ICE and still be about the same power output. So is the 20 HP similar to a 200 HP value for an ICE?

And similarly, how does one interpret the torque value? If I look at the technical specs for a 1979 Midget, the maximum torque is listed at 77 lb-ft at 3000 rpm. How does that compare to 105 lb-ft from a hub motor. Is the transmission gearing the important link that changes everything? As I type that, I'm thinking thats the reason why 1st gear is easy to start in, and 4th gear not so much.

"Perhaps if we built a large wooden badger"
"Runawayyyyyyy"


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## sunworksco (Sep 8, 2008)

Even IF the hub motors were efficient, it is like installing a heavy jackhammer on each wheel. Unsprung weight for an EV is very important to keep at a minimum.


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## PStechPaul (May 1, 2012)

Well, this has been hashed out in several threads already since I joined, and I'm still pretty much a newbie. But I realize that the concepts of HP and torque can be confusing, and even though I attended a top notch engineering university (JHU), I did not really unerstand motor speed/torque/HP curves until many years later. 

A general "rule of thumb" is that you can use an electric motor of about 1/3 the HP rating of an ICE in a car, and get just about the same "feel", if not an improvement. For one thing, the HP ratings you see advertised for cars and trucks are usually peak values for a "blueprinted" engine, and what you actually get may start at perhaps 20% below that. An ICE often has a narrow range of maximum power and maximum torque, and steep drop-off below and above those ideal RPMs. So to get maximum performance they are equipped with a 4-6 speed gearbox and it takes some skill (or a well-designed A/T) to shift at the right points.

What you actually "feel" when you drive is thrust, which is the forward force exerted by the tires on the road. This is derived from the torque of the engine through the transmission and differential. At low speeds, you need enough torque to propel the vehicle up any hill you may reasonably encounter, such as a driveway, which can easily be a 20% grade. And you also want to be able to accelerate, which is really the same thing as gravity and hill climbing. So you need to determine the minimum thrust as a starting point. On a 20% grade you push 20% of the car's weight so a 2000 lb car needs 400 lb of force. This is also 0.2G, or 1.96 m/s/s or about 4.4 MPH/sec. 13.6 sec 0-60. 

Power comes into play at high speeds, whether to overcome wind resistance or to be able to climb hills and accelerate with heavy loads. It is possible to get a motor which has sufficient torque for take-off and also a high end capable of highway speeds, but it will be large, heavy, expensive, and inefficient. But sometimes the removal of he weight of the transmission and differential can compensate somewhat. 

Please read the other threads on wheel motors and direct drive and general power/speed/torque discussions. Good luck.


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## RIPPERTON (Jan 26, 2010)

These "hub motors" dont necessarily have to go in the wheel.
Im doing feasabilty on running 2x 7kW Kelly motors inboard in my Diahatsu 
Mira 650kg.
basically where the diff used to be and bolted flange to the inner cv joint.
The longer of the 2 shafts would be cut shorter to make room for the 2 motors bolted together back to back.
The stub axle of the motor would be cut short and maybe bigger cabling fitted.
The inboard concept negates re-engineering your brakes steering and suspension, way too difficult and dangerous.
I asked Fany if there was a higher turn motor available to run on higher voltage but no options.
wait and see


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## major (Apr 4, 2008)

RIPPERTON said:


> These "hub motors" dont necessarily have to go in the wheel.
> Im doing feasabilty on running 2x 7kW Kelly motors inboard in my Diahatsu Mira 650kg.


Hey Rip,

Remember this? http://www.diyelectriccar.com/forums/showpost.php?p=201744&postcount=118 It appears to have less than favorable results. One reason is that you lose the mechanical advantage of the gear set. Wheel speed is far from optimum for electric motors. How would your bike run with the sprockets equal size?

major


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## ruckus (Apr 15, 2009)

Yes, this is re-hashed often with everyone playing the same position on the field. Here's mine again.

1. Direct wheel drive is quite possible. A quick google of "torque motor" will reveal MANY low-rpm high-torque motors. Are they cheap? no. Not yet.

2. Torque. For those math-challenged, I'll make it easy. A typical ICE with 100ftlbs also has a 2nd gear of about 2 and a diff of about 3.3 and ends up getting about 600ftlbs to the 2 axles. Divide by 2 tires and you get 300ftlbs needed per wheel. (first gear is only because ICE is very weak at low rpm. Once you get going with an ICE, you can climb most any hill in 2nd gear). This can be simplified down to ICE torque X Diff ratio = needed axle motor torque.

3. RPM. Without the gear reduction of the differential, your motor needs to have a max of about 1500rpm for high speed driving, and about 800rpm for a commuter. So as Major points out, a motor designed for 6000rpm is going to be WAY unhappy in commuter traffic at 4rpm. Look for a 1000-1500rpm motor.

4. Unsprung weight. RED HERRING. This is a completely bogus argument unless you are in the Paris-Dakar rally. Ever change a truck tire? How about a dually? Any solid axle vehicle has HUGE unsprung weight. This is an imaginary problem. Sure, your Porsche will outhandle my dually diesel, but unsprung weight is the least of the reasons why. Drop this argument folks.

5. So the recipe is fairly simple. Low-rpm motor with torque equal to 3x the ICE.

Happy shopping.


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## major (Apr 4, 2008)

ruckus said:


> Yes, this is re-hashed often with everyone playing the same position on the field. Here's mine again.
> 
> 1. Direct wheel drive is quite possible. A quick google of "torque motor" will reveal MANY low-rpm high-torque motors. Are they cheap? no. Not yet.
> 
> ...


Yes, so the motor Ripperton is considering is 5 to 6 times shy on torque.

So he will have a very sluggish car or need 5 or 6 of those motors or a good motor and a gearbox.


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## ruckus (Apr 15, 2009)

major said:


> Yes, so the motor Ripperton is considering is 5 to 6 times shy on torque.
> 
> So he will have a very sluggish car or need 5 or 6 of those motors or a good motor and a gearbox.


YUP. 

But what about this approach by some students?

http://gasoline-electriccars.com/07...lize-wheel-motor-plug-in-hybrid-retrofit-kit/

200ftlbs at 80v. Crank up the voltage a bit and you are there.


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## major (Apr 4, 2008)

ruckus said:


> YUP.
> 
> But what about this approach by some students?
> 
> ...


Get real. We've been thru this POS.


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## ruckus (Apr 15, 2009)

We have? Maybe I missed it. Haven't been following the curvy road of wheel motor development lately.

What is the problem with this approach? (assuming they seal this thing from mud)


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## major (Apr 4, 2008)

ruckus said:


> We have? Maybe I missed it. Haven't been following the curvy road of wheel motor development lately.
> 
> What is the problem with this approach? (assuming they seal this thing from mud)


http://www.diyelectriccar.com/forums/showthread.php/wheel-motor-affordable-20591p24.html Starting at post #233.


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## ruckus (Apr 15, 2009)

I found a lot more 'hash' than data. I was asking about the 'approach' not the actual product.

Personally, I agree that the technical difficulties of getting a wheel motor to fit in and around all the existing junk is a serious problem. 

However, if a serious engineering firm took it up and completely redesigned from the ball-joints out (or in), it is 'possible'. Look at some of the insanely complex hybrid designs coming out. Crazy for a DIY'er, but no problem for Ford or Porsche. 

Bottom line: possible for $$$

Cheers


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## major (Apr 4, 2008)

ruckus said:


> I found a lot more 'hash' than data. I was asking about the 'approach' not the actual product.


I think the 'approach' was covered here http://www.diyelectriccar.com/forums/showthread.php/wheel-motor-affordable-20591.html


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## RIPPERTON (Jan 26, 2010)

major said:


> Hey Rip,
> 
> Remember this? http://www.diyelectriccar.com/forums/showpost.php?p=201744&postcount=118 It appears to have less than favorable results. One reason is that you lose the mechanical advantage of the gear set. Wheel speed is far from optimum for electric motors. How would your bike run with the sprockets equal size?
> 
> major


Doesnt make sense Major
your forgetting the electrical gearing.
My motor would run fine on same size sprockets if it had 40 turns per coil instead of 28


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