you didnt know that? 
basically its self induction & lenzâs law - electrons are moving in the field of the permanent magnets which accelerates them, following lenzâs law, against the flow of the outer current from the esc. back emf feels like a really weird term for that basic principle. to put it super bluntly: a motor is always also a generator and the generator produces a current that works against the ESC current until it cancels out.
YES it was rushed a little bit, but also the video is very long for youtube, 17mins is long! I had filmed a whole section of me talking about the experience but never included that because it was just too much content. 10 mins should be the target.
Hummies are faster over long distance, really no need to show the slower one doing the same lap but slower.
I think it is logical to focus on engineering & performance first, once the design is solid & performs well in the environments we like to ride i think then the focus will shift to the other things such as comfort. Adding more urethane to a hub motor will make it more comfortable but it will also mean smaller stator which means more heat.
Temperature was my main focus, high temperature kills motors, destroys magnets, melts insulation & burns vescs, it needs to be minimised. It also burns skin!
Also, pretty much the shitiest motor you could find will work on flats, top speed on flats is not a test of anything. The most important data is hill climbing speeds, starting torque & temperatures.
Technically speaking the problem with jacobs urethane slipping would mean the data from top speed lap would have to be omitted anyway. There is no easy way to ride at top speed on a set of hub motors that are vibrating and bouncing up & down. It just would not be reliable data so it was omitted. Even if jacobs hubs were rolling smoothly they still would not beat the Hummie Hubs on the flats. Electrically speaking they cannot win that race so it is a pointless exercise.
If i was trying to be biased i could have just omitted that info about the hummies being faster & not mentioned the problem with the jacob urethane.
Itâs true you did mention hummies were faster, and Jacobs had the urethane problem. I wished you talked more about the slipping. Iâm still not visually sure how they are slipping (side to side or on the circumference of the motor). I didnât see any video showing the slipping (except while riding, which was too far away to really see how they are slipping), or the results of the inside of the urethane after slipping. it was a lot of talk and showing of heat being an issue in hummies, with just brief mentions here and there that the urethane was slipping on Jacobs. You did many things right in that test. I personally would have redone the hill climb speed test. The one you got going on hummies had a really slow start, which was what killed his time. If you came at the hill with momentum, which you likely will in most real world situations, the climb would have been much faster, and they wouldnât have been quite so hot, and you would have a more realistic test. Iâve been doing many hill tests using the space cell modded to 25 amps per motor and measuring heat. To get from my house to hummies the other day, I got them up to 240 F not once, but five times. Had to take breaks and took twice as long as it should of. I havenât tried the steels on this route yet, but Iâm expecting much less heat biased on the tests we did last week. This route btw is uphill straight for 2 miles at around 5% grade, followed by 1 mile down, followed by 2 miles of either flat or slight uphill.
So long story short, heat is a problem with hummies aluminum. It wonât be an issue for those who donât have a lot of hills. The steel seem to run much cooler, and this issue seems to have been solved. Its funny how fast the industry is changing right now. Before you could edit and release this, both claim to have fixed their problems, thus meaning a re comparison needs to be done 
And what kind of temperature abuse can magnets on steel hubs take ? up to 200f ?
that alone wouldve been worth mentioning though, and you were apparantly riding a new softer urethane already! 
From what hummie told me, it should be around 300 F.
The steel should not get above 220 F. Even when I get them over 250 F, they cool down and return to normal operation in time (for now at least).
Again, this is why Iâm opting for a 4wd setup on the steel. I think the industry will eventually move in this direction more when prices for parts drop more then they are right now.
I rode at full speed with Jacobs urethane slipping and all at midnight in the middle of a major Street. It was quite an experience like riding a gas engine longboard with the vibrations and the slipping thane sounding like like pistons going off. I got 25mph at full charge not fast but enjoyable
I think the vibrations and bouncing are due to the slipping wheel, which apparently happens especially on softer urethane.
I wish I had a dollar for every time you spammed those motors of yoursâŚ
how expensive is the rotor with magnets? could sell urethane and rotor as 1 package with the upside of a really thick bond between those 2?
Iâm wondering how steel motors are cooler than aluminium ones? I thought aluminium has much better thermal conductivity. So where are you measuring the temperature? If on the steel, you would be measuring that the heat is not dissipated to the outside but still inside the motorâŚ
As an owner of a set of hummie hubs I would say this is not really necessary. There is no slippage between rotor and urethane. Changing the urethane is a matter of loosening 6 bolts per wheel that hold the retaining disk and slipping of the urethane.
all this technical data is one way of looking at this and itâs interesting to measure and compare all of this data. But in the end, does it really matter if one motor getâs you a couple of seconds faster up the hill or has 2km/h more top speed or getâs some degrees hotter than the other?
Now this is the most important fact comparing those motors! I suppose most people donât want motors that bounce up and down, no matter how fast they go.
Fully in line with whitepony here! How does a specific setup feel, how much fun do I get out of it, is it balanced, does it work, is it good for carving, speeding, going up the hills âŚ
Not picking on those who made the test / video, fully appreciate that it takes a hell lot of a time to do those. Please include some of the âsoft factorsâ as well.
Maybe you can give us still a quick summary of how the different hubs feel under your feet.
Thereâs really nothing like riding on genuine ABEC11 urethane and itâs a big reason why Jerryâs wheels are comfortable. Also he doesnât spam or try to science the shit out of me which is kind of endearing. 
I do say something like that in the video
