The hall sensor only improves the start up, they will be disabled once RPM increases.
The big improvements are due to stronger & larger magnets, big stator, Lots of thick copper for low resistance, high voltage & current throughput.
None of these advancements matters in a belt drive as the belt cannot handle it. So to get the most horsepower at the wheel you must use hub motors.
yes, and this is why they also use some sort of torque multiplier even with electric drive trains. sure direct drive is fine on a 2lb drone, but you’re not riding that are you…
and that chart might be one of the worse i’ve seen, if you’re going to use numbers now. it helps to not just throw up a page full. i know that trick of distraction. 
Direct Drive Motors scale very well! - They are no belts or pulleys on this rig http://omnihoverboards.com/img/bg_header.png
@onloop is a master of misdirection . Check his history and you will see he often changes his tune depending on what he is reselling.
The truth is belt drives are used on in much more powerful motors than we will ever see in eboarding and they work perfectly. If hub motors really were the best choice for performance we would see them used on performance applications on ebikes ect. but we don’t. We see reduction drives.
The beauty of electric motors is they have very high torque at low rpm but even seasoned professionals in the electric car industry will tell you have a gear reduction drive train is the key to performance.
The truth is hub motors look stealthy and are cheaper to manufacture than a more complex reduction drive. They do come with several comprimises in performance but the trade off is negligible if you don’t need range or hill climbing capability. If performance matters than you need gear reduction to attain an efficient rpm range.
I’m still failing to understand why changing the kV doesn’t have the same effects as a reduction drive. Do the torque/power characteristics of a BLDC scale linearly with kV? If not how do you determine them?
Because one is electrical power, and the other is mechanical power, you can’t equate the two to be even.
I thought power at the wheels = power coming from the battery - heat losses.
If Enertion managed to make the heat losses of a hub motor equal to that of a belt drive wouldn’t it have the same efficiency/performance?
Heat losses on hubs will virtually always be higher due to the 1:1 ratio. Low-speed and standstill torque will be worse and cause heat build up much faster and more than belt driven setups. You can use bigger motors like the Raptor 2 to mitigate some of this, but it still doesn’t offer the same performance as a drive train with a proper reduction.
Is this necessarily true if you halve the kV though?
If that was a 100kV motor, wouldn’t a 200kV motors graph look the exact same but with a vertical stretch by a factor of 2? Therefor if the motor was running twice as fast at all times (2:1 drive ratio) it would have identical specs.
If Enertions heatsink is as capable as he claims then it seems like the issues with hub motors are fixed… Another solution would be something like the Carvon v3, wouldn’t it have similar cooling to a belt drive since the motor is exposed in a similar way?
Heat is one issue, but not the one I’m talking about. Imagine trying to open a door. If you try to push it from the side nearest to the hinge, you’re going to have a hard time pushing it open. If you push it from the knob side, it’ll be pretty easy to open.
It’s similar with with hubs vs belt drive motors. It’ll take more force to get the door (motor) going for hubs since there’s no reduction (less torque). Direct drives would be superior to belt drives if weren’t creating a massive load on the motors by riding our boards.
And this is why I’m surprised we don’t have more people trying to copy starry…
To me, the perfect hub would be sensored with built in gearing. Starry seems to have their issues (mostly with batteries) and their motors are too small too. But a larger sized hub with gearing like that might solve these issues.
I think a big issue with stary is you’re doing the opposite of what the benefits of a hub motor would provide you.
Using gears will be very noisy (like stary) and one of the benefits of hub drives is that they’re quieter and stealthy. Also do to the gear system, your motors now become higher maintenance than reguar hubs. Metal gears constantly rubbing on each other for thousands of RPM will wear down the parts fairly quickly.
That said, I would still love a nice planetary gear driven hub board like stary in dual config. The stary being a single drive is what shy’d me away from it. I do LOVE their controller though.
I’ve built quite a few planetary drives, they are noisy and very fragile. I don’t know if Stary will be able to pull this off, but the concept is nice. But if there’s the slightest piece of debris or the misalignment, the gearbox will seize up and destroy itself. I’m not sure if a skateboard is the right application for this kind of gearbox.
Hey, kudos if they pull it off
I’ll be back on the hunt for a detailed explanation as to why a hub is more inefficient than a geared-drive as I’m curious as well. Maybe a really low kv could make all the difference. Under lesser loads, such as flat roads, a hub is more efficient on a bike than a mid-drive. And then comparing the mid-drive of a bike with its chain to a board’s belt the belt is much less efficient I’d bet
@Jinra hopefully can do comparisons with me in two or three weeks and we can talk real numbers on flats hills and mountains😆
I suppose this is why quad copters use hub motors.
I’d be interested to see if the newer hub motors coming out have similar hill climbing ability to a belt drive once they are already up to speed.
Like i said, direct drives would be better if they didn’t have to carry 150+ lb loads.
having lube for gears in a hub that is bound to leak seems like a disaster in the making.
Best explanation I’ve found: http://clevercycles.com/blog/2005/07/31/motors-and-bicycles/
Actually rhis doesn’t relate as it involves adjustable gearing to get in the good range. Neither system on a board really does that. You could say a pulley system does to some degree though. There’s more to it that isn’t explained in this
I think the main point is the general characteristic of all BLDC motors is that they are most powerful and most efficient at a certain higher RPM. Therefore we use gearing to make the motor operate in that most efficient RPM range for the most time. Hub motors even with low KV cannot move the efficiency band close enough to the low RPM speeds of a skateboard. Thus you will be using the motor at a less powerful and less efficient RPM range, during most of your riding.