Are hub motors worse?

I believe what the market is looking for is a board that has the speed, reliability, and run time. to drag ones butt up to the top of the mountain then allow one to freeride down then ride under power home the best of both worlds

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From Vedder.se :

http://vedder.se/2014/10/chosing-the-right-bldc-motor-and-battery-setup-for-an-electric-skateboard/

"So, regarding KV: different KV versions of the same motor are fully equivalent. KV only affects the battery and ESC choice. Therefore, while comparing motors, lets talk about torque instead of current because torque is proportional to current / KV and, as explained above, the KV value can be changed freely with the amount of turns and copper thickness.

RPM/Losses/gear reduction

Now we know that copper losses are proportional to the square of the torque produced by the motor, and at low RPM and high load they are dominant. As RPM increases, other losses start to add up exponentially. In my experience, these losses start to get significant around 60k electrical RPM, which for a 14-pole motor is about 8570 mechanical rpm (most 50mm+ outrunners have 14 poles, some unusual ones have 18). Because of the square relation, it is desirable to run at as high speed and low torque as possible as long as we stay below 8.6k RPM. To express the square relation in some numbers, having double the RPM and half the torque at a certain power output will cause four times less losses. The lesson from this is that: make sure the top speed you design the skateboard for is at around 8.6k rpm on the motor if you are using an 50mm-60mm outrunner.

For my longboard with 84mm wheels, where I would like to design for a top speed of about 35km/h with a sing motor, I would need a gear ratio of about: (35 / (0.084 * pi * (8600 / 60) * 3.6) = 0.257 which is 1:(1/0.257) = 1:3.9. Note that this gear ratio is independent of battery voltage and motor kv. Keep in mind that 8.6k rpm is not an exact number, but a guideline that seems to apply quite well to all 50mm-60mm hobby outrunners I have tested so far."

Understanding the matter, you realize that the motor design doesn’t have to much impact on the fact that losses build up with the amount of torque you squeeze out of a motor. If you want more torque at the same efficiency, your motor will get a lot bigger all of a sudden. Expect your comparable (to a geared system) hub motor to weigh 4KG and be huge in diameter (because of the square relation). You can’t cheat the physics! Most BLDC outrunner motors are already 80-90 efficient. When plotting the efficiency graphs, you could simply assume your motor to be perfect.

All of a sudden you start to realize that the motor design doesn’t matter to much. So you end up with the fact that you need to accept the losses, which will be converted into heat. Losses = Heat and vs. So any hub motor will need the best cooling possible to shift those losses (heat) away from the stator/magnets into another part being cooled by e.g. air. In case of a skateboard this is most likely the the hanger, sitting above a potentially hot tarmac surface, since the motor can is wrapped in heat insulating urethane. Your losses can easily reach values as high 200-400W, especially when going slowly up an incline or ride against the blow of wind. This is why you need a twin drive to cut the torque needed in half, since copper losses are proportional to the square of the torque produced by the motor.

So if you want to keep comparison fair, you always need to compare single drive to single drive.
Another fact that is very often been overlooked is the following: If you managed to build a super torque rich small and light motor that could be used inside a skate wheel, it could also be used in a geared system, all of a sudden starting to perform a lot better. So in a comparison you should always compare the same motor - used inside a hub, and used in a geared setup. Anything else is cheating yourself.

Another thing that is often misunderstood are the losses of the belt drive itself. Compared to the inefficiencies of a hub, that is nothing you need to worry about. The belt system Benjamin and I tested was more than 97% efficient. The reason why coasting is better without belt drive is not the belt drive itself. The motor inside a belt driven system is simply performing better as a regenerative brake, since it is geared. Hubs do also need to be debated from the generator point of view.

Frank

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@JohnnyMeduse , You don’t need to readjust belts constantly…Timing belts don’t stretch. Ask any professional automotive mechanic. If they did can you imagine how many non tinkerers would have a pile of cars in their front yards?

Timing belts were around long before E-skate. I’m not saying people don’t have issues with belt driven setups. They do. But all of them are related to misalignment, poorly made parts and bad technique.

I also have to add. Is there anything better than a well made non motorized Longboard with nice trucks and good quality cushy wheels? If you spent a day out riding a perfect longboard what would be the first thing you think you could change on that board without affecting how it feels to ride it? Would you change those cushy wheels to something with less urethane and a bigger metal core? Not me.

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True but if you don’t take a look at your setup and adjust the belt tension, because stress and vibration are loosen up screw on you motor mount, on a daily or weekly basis you take the risk to get a broken belt. ( here is some example. )… It a process you learn from experience… but the market isn’t people with experience, and they most likely get tired of it…

Ride quality is more important to me. There are a couple of different subsets here it’s true. People are mostly concerned with looks and that pays the bills, but c’mon! There’s no comparison when it comes to the feel of quality longboard components. You can have belted systems without compromising the ride.

The only exception with what I’m saying is Carvon’s V3 direct drive.

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A post was split to a new topic: Hub Motor & Urethane Riding Qualities

This forumla might be true for the electrical theroy alone.

But we are talking about magnetic electric machines.

The permanent magnet strength, specifically the magnetic flux field strength, is a torque multiplier. Increasing Current is not the only way to increase torque output from the machine.

It seems the Vedder formula assumes all motors generate the same torque per amp.

So is It is possible to overcome/reduce the low rpm copper losses with improvements in the motor design alone? I think it’s possible and I’d be happy to be proven wrong.

For better motors esk8 designers need to start thinking about electro-mechanical engineering, not just Electric theroy.

This is why Raptor 2 can outperform belt drive systems. This is why we offer 110% performance guarantee.

Everyone said hub motors were shit, even I said that… The problem was people didn’t look outside the box…

Vedder is a smart guy but his formulas shouldn’t dictate what engineers should and shouldn’t try to achieve. It’s time people open their minds and continue to push hard to innovate. We should be trying to prove Vedder wrong, not simply sit back & quote his comments and bury our heads in the sand.

Trial and error is a powerful formula.

Just what EXACTLY do you mean by “outperform”?

I watch these Telsa’s tear some other cars a new one off the line but then the other car blows by after a 1/4 mile or so. Which one performed better? If a board is really good for the first 1/4 mile up a hill before requiring the rider to carry it, is that okay? If a board is fast as all hell but unsafe at high speed, how do we measure its “performance”. Do we care about the rider experience, such a comfort, fatigue, security, and fun, or do we just quote telemetry readings and specs off the BLDC tool? Is range the key issue? Speed? Is carving, turning, drifting, stability, and control the bigger issue? How about being fast off the line?

What about a rider being able to configure his board to perform the way the HE defines performance? Can you get a different split in truck geometry front and back? Can you switch to bigger/smaller/harder/softer wheels in a jiffy? What about cutaway deck shapes that allow for off-road wheels. Is that same motor good for EVERY wheel size, or just the one that comes with the complete?

I know that I’m different than a lot people, in that I demand a lot of options and configurations. But there are so many great ways to skate, I can’t imagine that everyone would be happy with a “one size fits all” approach.

I believe that performance, like beauty, is in the eyes of the beholder …

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Yes, all the yes.

@onloop how about we keep things apples-to-apples:

Take the Raptor 2 motors out of the hubs. Rewind them to 3 times the KV they currently are. Put them in satellite with a 3:1 reduction.

Hubs are better? Seriously???

Torque would be better in satellite, and top speed efficiency might be better in a hub configuration.

Who wants what?

Different strokes for different folks…

torque at the wheels, acceleration, top speed, range, watts & surprisingly efficiency - this stuff can be measured.

Yes, its possible and will be available soon.

YES, can change urethane easily. We will be selling these in about 2 months.

http://cdn1.bigcommerce.com/n-yp39j5/zad02/images/stencil/1280x1280/products/183/1212/RSPEC-CROSSOVER-ELECTRIC-SKATEBOARD-WHEELS__52943.1493399099.jpg?c=2

YES, our modular electronics can be swapped to any deck! In fact, our electronics can power any motor you choose, even Carvon V3 (FOCBOX bulk pricing available)

ALSO, we have some new decks designs coming soon.

No, to maximize performance the motor must be custom designed for the specific application, retro-fitting & adapting motors with belts (evolve) is never going to give the best performance.

I mostly disagree with that,

I suppose it needs to be defined, Objective performance VS Subjective Performance criteria.

Objective performance needs to be measurable & comparable against other objective evidence.

If you make a claim about performance, i think it is important that you can measure it. If you cannot measure it then it is not really “true” performance, it a subjective / opinion based view of performance characteristics.

EXAMPLE: a pro-Skater in the SLS league will say ABEC11 wheels are too big, heavy, soft & perform horribly for skating the streets & doing tricks. This is subjective.

However, you could measure rolling resistance, durability/life span, top speed… That is Objective Performance Evidence and hard to argue against.

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I am not trying to say one method is better than another method. At this stage everything can be improved.

I am simply saying this.

  1. Raptor 2 hub motor design is doing things that most people assumed was not possible with hub motors. I am trying to change the conception of the market that hub motors are shit. I think my videos are very good evidence that the market has mis-conceptions about hub motors, I believe the Raptor 2 is proof that hub motors can work very well in esk8.

  2. I am also saying that It’s very likely that the results we are seeing are due to the motor design improvements. Its not magic, we designed an improved motor & got improved results. Simple, anyone can do this with R&D, time & money.

  3. Finally, The Raptor 2 will outperform all existing commercially available mass produced electric skateboards that use hub motors. It probably beats most satellite motor setups too. This is why we offer 110% performance promise.



EXAMPLE: If we make a competition, specifically to see what electric skateboard has the most torque that the wheels I would have two options,

  1. Take my hub motors & install a 20mm+ wide belt & pulley and take advantage of the mechanical torque multiplier gain by using huge reduction gearing.

OR

  1. Make a better/bigger hub motor.

Eventually, there will be a clear winner, the design constraints of one approach will be the limiting factor eventually… I haven’t done this exercise so i don’t actually know what the best drive train is for esk8… All i know is that i have achieved some amazing results & probably shocked lots of people who didn’t think it was possible.

If we make a competition to see which esk8 can achieve the highest top speed, the design will be different again.

Each performance criteria, torque, speed, heat, weight, etc can be a single focus for the engineer, but eventually, we want a good all round performer that is reliable with minimal maintenance that does everything very well.

That is why I believe hub motors will eventually dominate the industry. I am more than happy to be proven wrong on this :slight_smile:

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Take an Inboard M1 hub motor - weigh it.

Take a Raptor 2 hub motor - weigh it.

Performance from a power / torque stand point would likely proportionate to the weight difference as a percentage - assuming battery and programing are the same.

Comparing hubs and belts without the same motor, battery, and programming is a marketing joke IMO.

Hubs and Belts are different, and have their places - both will be around for a long time.

Stay tuned for more episodes Marketing & Posturing…

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To summarize: Horses for courses…

You got know what you want from your board and where you ride it. Some questions you could ask yourself are:

  • Are your roads rough?
  • Do you face steep hills often?
  • How is the climate in your country (hot, cool, ambient)?
  • What is your weight?
  • Do your feet go tired soon, riding a board?
  • Do your feet/legs accept vibrations?
  • Do you want flex in the deck?
  • Do you want to use your preferred wheels and shore hardness?
  • Do you want your board to look like a regular, non electric board?
  • Do you want the best possible acceleration (even up a hill)?
  • Do you want the best coasting experience?
  • Do you want max range?
  • Are you a beginner, average rider, pro?
  • Do you want to use your preferred deck/trucks?
  • Are you a speed freak or do you enjoy cruising and carving?
  • Do you want to win Pikes Peak or a drag race?
  • etc. etc.

These questions need to be answered by yourself before making a decision. Very often it happens that you want to combine things that you can’t without accepting a compromise. Designing and riding boards for almost 15 years now, I have an advantage in making my decision. @ChrisChaput probably has his own opinion about urethane wheels, since he knows everything about them and tried out a lot. He probably loves that ultimate smoothness in the ride and the sound of top notch thick urethane attached to a pro board. So you will probably not see him flying past you on hubs, since his toenails would curl in horror.

Users, being new to e-boarding, do not have our experience. They often buy on visual impression and promises. This is a bonus for hubs. Experienced riders will consider more factors, but could still end up on hubs or a geared setups. Again, horses for courses and personal preferences…

Personally I prefer

  • max. vibration dampening
  • nice flex in the deck
  • Personally I love pneumatics, since they are a big relief for your feet and bones and you can even ride on cobble stone roads with ease and a smile on your face.
  • I do also like urethane wheels with high rebound, using a thick layer of urethane, especially when carving down the relatively rough concrete airport runways.
  • Fantastic acceleration and range - I love to know that the battery lasts for 40-60Km.
  • I ride mostly on flat terrain, so I ride a single drive, having only one ESC and motor to care about.
  • I like things to stay as cool as possible, even when pushing my limits.
  • I love powerful twin drive MTBs for off road fun and touring (how could I not).
  • I still love the appearance of hubs (everyone probably does).

I know that I am in the comfortable position to be able to build every board I can dram of. Not everyone can afford three boards, nor does everyone have the knowledge and skills to achieve what skilled DIYers can achieve.

Horses for courses is my conclusion. The more informed the customer is, the better he can make his decision. So we will try our best to serve each customer with the perfect board, according his abilities, weight, terrain and purpose of usage. In some cases a hub might even be a good choice, depending on your personal preferences, path and the climate you live in. There is no one shoe fits all.

“Are hub motors worse” is to simplifying.

Frank

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@onloop I’ve said what i came here to say.

I’m not getting into this argument because people are making money selling their particular solution so that solution will only ever be the right one for the people who have the money to market it.

And hubs are cheaper and easier to manufacture and assemble on the board than belt systems. Let’s just make that part clear because when it comes to selling electric skateboards, or any fucking other thing for that matter, shaving time off of assembly and shaving parts of the list is about saving money and making money. ITs not about performance. It’s partially about reliability. Its all about money. Its not about creating a custom experience for the rider unless you’ve got a pile of various KV rated stators sitting on your shelf ready to dial it in for that one guy with his one application. And if its not about getting the rider exactly what they want, then what’s it about?

You’ve had a vast amount of success leveraging the DIY community to build your completes, and now you’re gradually moving (while still popping in now and then and keeping the forums going and providing a lot of content and good info and luring people into the sport) toward being a factory touring suit who used to skate and still looks good in a muscle shirt. Don’t do that. Stay here. We want you here. This pattern of invent something, use it to make money and invent something else, then talk shit about the old thing and how it never made any damned sense so you can sell your new thing… its almost a circle jerk of marketing. And now seminars on how… to sell… and market… WTF even are you anymore?

I swear to god if you go pyramid scheme on us and sell books on esk8s that tell you how to sell books on esk8s i will swim to Australia and beat your ass with a broken gen 1 raptor deck. Don’t forget where you came from.

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Did I say how much I like Abec 11?

I love hard carving and long slides, and this exactly my only concern about the raptor 2, I’m completely confident about the whole system like focbox, nano-x, the torque or speed from the hubs, etc…Just that, how the thanes will perform for hard carving and sliding, I hope to see collaborating enertion and abec11 soon!!

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Dude, ride a Raptor 2 then lets talk…

alternatively, watch this video

Tell me you are not slightly curious about R-SPEC GHOST hub motors now? I wouldn’t have believed this was possible 12 months ago…nobody did!

Are you impressed by this performance the slightest bit?

  1. They look awesome.
  2. No maintenance.
  3. No need to align belts.
  4. No need to adjust tension.
  5. Can swap out to different urethane designs easily.
  6. More torque at the wheels compared to 9mm belt drive.
  7. 30% Hill climb ability.
  8. Fully closed design. No sticks, rocks, dirt can’t enter the motor.
  9. Motor Hidden inside wheel, protected from damage by debris.
  10. Faster to install.
  11. Same cost as our previous R-SPEC outrunner motors.
  12. Steel structure for incredible strength.
  13. Larger bearings to handle loads better.
  14. Improved cooling methods.
  15. Precision Trucks for improved handling.

The only negative people can come up with is the urethane is too thin…Lucky we are running premium urethane on the front where most of the rider weight is!.. if that’s the only complaint people can come up with I’d say i have absolutely nailed it!



LET’S JUST BE HONEST

EVERYONE SAID HUB MOTORS WERE SHIT!

EVEN I SAID THAT - & mostly because it was TURE they WERE SHIT

Well, it turns out they are pretty fucking good now…

I’m the guy that is going to be the number 1 brand in electric skateboards industry, or die trying!

ALSO, you know the real reason i did that seminar, I actually need my old DIY parts competitors to grow stronger. The reason I need you guys to grow stronger is that you can all help me grow my business stronger. A rising tide lifts all boats!

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@Blasto I think you should weigh in here. Based on your posts I’m assuming you’re one of the engineers on the Enertion team behind the motor and you probably have the most data since you’ve had the R2 hub since Feb.

Did anything come out of your tests? Is your drive more efficient than existing belt drives? Is less heat produced on sustained high speed on flats? On hills? On long rides over 5 miles? In belt drive systems, is the belt the weakest link in improving performance?

I did 25% grade hills on hubs a year ago while still maintaining 20 mph. I said back then hubs are the future. I knew a slightly larger motor with sensors was going to mean I could climb 30% + hills.

That videos a little deceptive too. 30% for a portion, but not the entire hill.

If you want me to show you some hills in San Francisco that are 30% grade for 1000 ft or so, I’d be more than happy. I would say based on the tests I’ve seen in video so far, the raptor 2 motors are close in strength to hummies v3 motors.

One thing we do agree on, hubs are the future. Hubs will shine through this year!