12 turn Hub-motor vs Mid-drive for hill climbing ??

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Hugh-Jassman   1 kW

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12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Hugh-Jassman » Feb 19 2019 2:58pm

Image

I think someone should do a comparison test between a mid-drive and a hub motor with 10 to 12 turn winding with or without gears. How much energy would it actualuy use in a given hill climbing compairison. Same total combined weight, speed and steepness of grade? With the price of batteries being so high I think this would be a good thing to know.

I think the only way to build a gearless power system with hub motors would be to use two; the front wheel would need a 5 turn winding and the rear a 12 turn winding, then literaly switch between them. This would be good for hauling a total combined weight of 500 to 600lbs on the same steep hills. But if there is a weight limit of 200lbs on each hubmotor I would need three wheels.

After setting up my CycleAnalyst I drove my bike with Cyclone3000 up the short hill up to my house with two arm loads of fire wood in my trailer [about 450-475lbs total combined weight] while in the high gear [11:1 ratio] drawing about 1400watts then in the low gear drawing only about 600watts [20:1 ratio]. For most hills I use a 16:1 ratio making it 3 seperate gears that I use. [My drive wheel's tire is 23” diameter. The ratios include the 6:1 planetary gear reduction in the motor.]

No-one ever says anything about how little power is needed. I would really like to hear from someone with a 5:1 geared hubmotor with at least 10 turns. A voltage multiplier is just a way make it possible to burn more amps.

I have been using around 37 to 43 Wh per mile depending on whether I climb a hill or not. Averaging 10.2 mph. I must recharge for 45minutes at the food-co-op before driving home. Because my 52v battery is only 13.5 amp hours that cuts off at 39 volts, and I charge to only 90% before leaving on my trip to town. Aprox. 10 miles round trip.

The Cyclone can out put 3000w only at 72volts and I don't want to get anywhere near that.

Does any one know if the Cyclone Mini is a faster RPM motor, thereby needing the larger 9.55 to 1 gear reduction?? or did they do that to make it more street leagal.

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Grantmac » Feb 19 2019 3:27pm

What are you trying to achieve? Faster speed on that hill? Less overall battery use?

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by billvon » Feb 19 2019 4:32pm

Hugh-Jassman wrote:
Feb 19 2019 2:58pm
I think someone should do a comparison test between a mid-drive and a hub motor with 10 to 12 turn winding with or without gears. How much energy would it actualuy use in a given hill climbing compairison. Same total combined weight, speed and steepness of grade? With the price of batteries being so high I think this would be a good thing to know.
There are so many ways to compare that would be hard. Varying hill steepness or one fixed grade? (hubmotor can be optimized to one grade) Downhills? (no regen in geared hubs or mid-drive so no energy recovery.) Top speed on flats? Efficiency on flats? Etc.
--bill von

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by district9prawn » Feb 19 2019 6:02pm

A good start would be to compare the resistive losses of the motors from their kv/kt and winding resistance when they are making the same torque at the wheel.
Neu 8057 6kW left hand drive hardtail with 18 fet Vesc: viewtopic.php?f=6&t=96754

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by markz » Feb 19 2019 9:17pm

A 12T motor is not good because a 12T would have very long wires that are really thin compared to a 4T which has shorter wire that is really large which can take more amps, more amps means more power. Then to get some added torque, you just reduce the circumference of the wheel, say go from a 26" to a 24" or smaller.

There is no difference between a 12T and a 4T other then mentioned, the 12T does not give you more torque because the 4T can do exactly the same by playing with the settings, installing thicker phase cables/battery cables reducing the resistance even more.
We discussed it to great lengths here...
https://endless-sphere.com/forums/viewt ... &start=625
yes its in there somewhere

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Triketech » Feb 19 2019 10:52pm

I did something similar with a trike.

Mid drive won over a geared hub but I prefer the geared hub.

http://www.triketech.com/Drivetrain/Pow ... Drive.html

http://www.triketech.com/Drivetrain/Pow ... AC-V2.html

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Chalo   100 GW

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Chalo » Feb 19 2019 11:52pm

The difference between the two kinds of motor for hill climbing is that you can configure a hub motor for a certain steepness and load, but you can potentially set up a mid-drive for any steepness and load.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Hugh-Jassman   1 kW

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Hugh-Jassman » Feb 20 2019 2:08pm

very inlightening, thanks...I will read more

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Hugh-Jassman   1 kW

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Hugh-Jassman » May 15 2019 2:29pm

Not sure I understand this....it looks like the thrust drops off too fast, I would need to fine tune the turns to fit my climbing situation?

turns comparison.JPG

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Chalo   100 GW

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Chalo » May 15 2019 2:49pm

Hugh-Jassman wrote:
May 15 2019 2:29pm
Not sure I understand this....it looks like the thrust drops off too fast, I would need to fine tune the turns to fit my climbing situation?
There's a bug in the simulator there. You've specified 9% grade, but if you look in the results, it's calculating for a flat 0% grade.

When I move the slider on the graph over to 9.0% grade, it says the 12T motor will climb at 12.3mph and overheat in 7 minutes.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Hugh-Jassman   1 kW

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Hugh-Jassman » May 15 2019 3:27pm

I think the grade turns off....not sure why. and I tryed it on a different browser:
but I still do not understand it.

TURN COMPARISON.JPG
Last edited by Hugh-Jassman on May 17 2019 3:05pm, edited 1 time in total.

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by wturber » May 15 2019 4:17pm

Not sure what is going wrong, but System A shows a 14.7% grade in the chart and System B only 4.3% even though the sliders show 9%.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by wturber » May 15 2019 4:23pm

OK. Turning the Black Curve to "%Grade" causes the odd behavior. Change it to "Load Line" and the simulator works fine.

https://www.ebikes.ca/tools/simulator.h ... throt_b=90
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by markz » May 15 2019 4:50pm

Chalo made a great point, there is a lot of versatility in mid drives, whereas buying a motor you are stuck with the winding count. I forgot to mention about the shorter thicker windings 4T vs longer thinner windings 12T is there is something called "TORQUE per Amp", I do believe is what its called. I know its Amp per __(something)__
I found this excel spread sheet, could be the term I am looking for.
https://endless-sphere.com/forums/viewt ... W#p1457521

Another thing people talk about is efficiency, like Nepronix (sp) found the Leaf 1500W and found it to be efficient. I haven't quite understood that aspect of our hobby/means-of-transportation yet.

TeslaNV also did a bunch of stuff, in the MXUS 3000W thread, where he tested or calculated how many amps a 4T could handle versus say an 8T, and it was quite significant, since I am bored and going to ramble I will see if I can find it for you. Mind you it a direct drive motor, keep in mind. I am sure its the same for a geared hub motor. Like I said before, I just dont like the sound of the gears meshing, the sinewave controller may fix that problem, perhaps even FOC controller would fix it too. Yes, the $500 mini Grintech controller would be ideal, perhaps one day.

This talks about KV and resistances
https://endless-sphere.com/forums/viewt ... W#p1345068
Same post, that is post #1, near the bottom of post #1 gives the reader some insight as to how much Amperes each winding can take.

In the example below, you can see it is significant. But like I said, its a teeter-totter, it is give and take. You can take the 3T and slam it into a 20" bicycle rim, but when you run over a pothole it wont be good. But staying with a 26" bicycle tire, you can go over the pothole more easily. I find with my 4T, it takes some time to get up to speed in a 26" wheel, but if I were to lace it into a 20" I would get up to speed much much much faster, be able to climb hills longer without overheating, climb hills faster, using less amps.
3T:
Max. Continuous Phase Current: 55A
Overheat in 10 Minutes: 85A
Overheat in 60 seconds: 242A

6T:
Max. Continuous Phase Current: 30.3A
Overheat in 10 minutes: 47A
Overheat in 60 seconds: 132A

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by MadRhino » May 15 2019 5:44pm

Theory says mid drives are best, because you can change gears for the task. Yet, practice says hubs last longer and require less maintenance. At both end of power requirements, driving the chain has an advantage: very low power or very high power. In the middle, hubs are winning in all aspects of maintenance, durability, and performance.

But, the rider has a lot to do with this, for he can make any system running for the best or the worst. The mountain is pro riders domain, where no systems can make a winner over balls and experience.
Make it fool-proof, and I will make a better fool.
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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by dogman dan » May 17 2019 9:08am

Well, I can report that a bike and rider weight of 400 pounds, up 5% grade, melted down a 10 turn 5-1 geared motor easily. I did the testing for EBK, so they could state the limits of their motor warranty.

So for that firewood, it would be more efficient to run a mid drive, than waste enough energy to set a motor on fire. 8)

If the bike weight is under 300 pounds, the 10 turn motor is reasonably efficient up hills and does not melt. Your mid drive motor gets warm too I'm sure. But it can gear down and run 5 mph. 5 mph up a hill overloaded, will melt the geared hub motor. Reasonably loaded, the geared motor will climb the hills at 12-15 mph, and run pretty efficient.


A 12 turn motor does not really increase its load limit on steep hills. It will increase its efficiency at lower rpms, at normal load.

It does increase the load limit on the flat some, but on steep hills only more power will help.

Bigger motor, more copper fill, more magnet, and more watts will mean a higher load limit for a hub motor. A smaller diameter motor IS gearing it down, and will increase the load limit noticeably for a lower power hub motor. Big motor, and small wheel for the win, if you want an efficient hub motor and a large load limit.

The motor that melted was running on 48v, 22 amps controller limit. The standard EBK controller. The sim, when used correctly, will show similar results, meltdown comes pretty quick when you overload, and run up steep hills.

But the stock e bike kit geared motor, and controller is quite capable of taking 300 pounds total weight up a big hill. How big? How about Emory Pass in NM. 10 miles of continuous hill. Grade mostly 5-6%. But at the top, the last mile is 10% In profile, it looks almost identical to the Alp D Huez climb in the tour de france. So it makes it up most any paved hill with grade under 10%. Dirt riding is different, grades often steeper, but also so rough it can be impossible to ride fast enough to not melt a hub motor.


Nothing is set in stone, conditions, and the balls of the rider can be far more important.

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by spinningmagnets » May 17 2019 9:21am

There are many factors and variables. A 16-inch moped rim has a tire with roughly the same diameter as a 20-inch bicycle tire. If you used a direct drive hubmotor with efficient thin laminations it would run cooler than common thick laminations in a 26-inch wheel.

Then add ferro-fluid to help it shed heat, and you could climb significant hills without gearing (John in CR, etc). Luke has mentioned he feels the low turn-count versions have shorter coil runs, and he feels the lowered resistance is a huge benefit.

I take that to mean...if voltage is set...its better heat-wise to have a fast Kv motor at half-throttle to achieve "X" speed, rather than a slow Kv motor at full throttle.

Just some thoughts for consideration...

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by MadRhino » May 17 2019 10:12am

Geared hubs have gears that are weaker than a typical bicycle chain, so it is better to use a BB drive then, and have the benefit of a gear set that can be shifted..

Big DD hubs are hard to beat, when they are heavy enough to shed the heat, and ridden in their efficiency zone. They make a faster bike, that you don't need to shift. Their downside is that you have to climb fast and avoid stop and go when climbing steep trails.
The downside of BB drives is that those small motors are hard to service and lots of parts can fail. You have to shift them in their efficiency zone all the time, that is making a distraction and lots of time loss in acceleration.
So, mistakes from the rider can wear both, but the amount of mistakes that can be accumulated with a BB drive is much more.
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Hugh-Jassman   1 kW

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by Hugh-Jassman » May 18 2019 12:22pm

Well I am really enjoying my Cyclone 3000 and I am thinking about the Cyclone Mini for my next Cycle-truck about this size. But maybe not, now I think I should use the larger Cyclone. And I want to use a 3inch motorcycle tire on a 16inch rim for the drive wheel. OD would be aprox. 22-23 Inches, same as my 19 x 2.25” moped drive tire. I really like heavy duty tyres for cycle-trucks; I will never use a bicycle tire again.

I got an indexed thumb shifter I can use on the left side which can help the shifting, but still it is a matter of timing [let off the accelerator then pedal while shifting and then accelerator again before my machine slows down too much].

I think hubs will never be good for steep hills and heavy cargo at street speeds, unless I could build a two speed gear box for it that can handle at least 1900w.


MadRhino wrote:
May 17 2019 10:12am
Geared hubs have gears that are weaker than a typical bicycle chain, so it is better to use a BB drive then, and have the benefit of a gear set that can be shifted..

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by markz » May 18 2019 3:43pm

The best of both worlds, a direct drive that is a mid drive!
The Stoke Monkey can be either geared or d.d. motor - https://www.ebikes.ca/product-info/stoke.html
Motor Choice

At the moment you have the option of either a direct drive Crystalyte SAW motor, or the geared G02 motor. The SAW motor from Crystalyte is in the same spirit as the original stokemonkey motors. It is rugged, a little heavy (5kg), and can take a fair bit of abuse before overheating. However, it also requires the use of a single speed freewheel to drive the motor chain, and when you pedal the bike without the motor this freewheel will make a familiar clicking sound.

The G01 geared motor option is based around a conventional geared front hub motor where a 16 tooth cog is bolted on to the disk mount. Much like in a hub motor application, the internal gear reduction allows the motor to produce more torque in a package that is smaller in diameter and 33% lighter than the SAW motor at just 3.3kg. With the fixed cog, the motor still spins when you pedal the bike unassisted, but the internal clutch means that there is no drag and also no clicking sound coming from the motor when you are just pedaling. The downside of the geared motor is in the small audible gear noise when the motor is running. It's not much, but for the quietest opration when powered the direct SAW motor is a better choice.

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Re: 12 turn Hub-motor vs Mid-drive for hill climbing ??

Post by markz » May 18 2019 3:47pm

For a custom fabricated bicycle or a cargo style bike that is lengthened, or whatever you could look into using an Internal Geared Hub (IGH) or two for more reduction choices. How the IGH would hold up, be any ones guess. Some say yay, maybe some others say nay.

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