Hub Motor & Urethane Riding Qualities

Urethane depth really does have a significant impact on the ride quality. I can notice a difference even between 90mm and 83mm Abec11 Flywheels at the same duro (75a, classic)

Side effect of lots of urethane… The wheels last forever. The 75a Flywheels on my push setup are a decade old now, and still at 86mm after thousands of miles


Stellar insight. Really glad you have become more visible and accessable to this community. Welcome Chis, thanks for these insights and making magical, unicorn farting rainbowesque, buttery as shit, smooth, wheels of the gods.


Tell that to Usain bolt, do you think the guy with the silver medal should have gold instead because he had a better running style?

You were the world champion in speed racing because you got to the bottom faster. You performed better, your wheels/gear was probably better too, but that was not the method the judges used to award your prize.

Anyway, this is stupid, Performance can be both Subjective & Objective…

Objective performance can be measured and there can be a winner, Subjective will lead us to have stupid arguments.

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They say that there are no stupid questions so here we go… :slight_smile: I never ride a longboard… did try skateboard few times but that was it. Now I want to build my eboard of some sort and I can’t understand why longboard wheels are shaped like they are? I belive 99% of videos that I saw was just riding straight with few not very hard turns. A big flat surface in longboard wheel = more friction and resistance, right? So maybe they should look more like roller skate wheels or something in between? Please guys educate me :wink:

First of all, there are a LOT of counter-intuitive realities in skateboard part design, and you just mentioned a BIG one. It’s kind of funny, but some of the WORST ideas in skateboarding come from really smart AUTOMOBILE engineers. I think this because they don’t differentiate from the lean-steer skateboard and the manual-steering cars, go-karts, and reverse trikes. They also tend not to understand that a gravity or push vehicle is grossly underpowered compared to a vehicle that weighs way more than the rider and has an awesome amount of power available to him, as well as a suspension system and the ability to countersteer. BMW Carver anyone? Rubber radiused tires, huge metal cores with swing arm type steering on a heavy metal brick of a deck? No thanks … no ultimate driving machine there.

Rubber and/or pneumatic tires can provide a tremendous amount of traction and control (Psychotiller’s Six Shooters and Carve Board tires come to mind) but if you don’t have a motor, you better have a chair lift and a steep hill around because they ain’t no fun to push. At least the Carve Boards are like that. Only tried Six Shooters under power and me likey.

On (dry) pavement the urethane wheel can be magically fast and smooth and you can dial in the amount of traction and/or drift that you want. You can make fast wheels that stick like suction cups, and fast wheels that you can push sideways, but in either case you won’t get greater “rolling resistance” with a wide wheel and/or wide contact patch. Just the opposite. Think of it this way. You’re driving your car on grass, sand, and dirt roads. Do you take the “road bike” path and use tall, narrow, highly inflated tires on tall stiff rims to “minimize rolling resistance”? Oh hell no. That’s about the worst thing that you could do. You want soft, wide, underinflated tires that keep you from sinking into the medium. Skaters should treat the board like a dune buggy in that regard. From a dead stop, my board with SIX 83mm tall ultra-soft high rebound 74a Centrax that are 78mm wide each will out-roll a board with FOUR smaller wheels of the same urethane. As I said before - counter-intuitive. 99.9% of skaters don’t know this, nor do they want to accept this. They will quote books and say things such as, “the smaller wheels will overcome the moment of inertia more readily and accelerate more quickly”. And they would be dead wrong.

In the mid seventies we started adapting roller skate wheels into skateboard wheels. Narrow 52mm medium durometer wheels. They only had to be narrow for roller-skating because of the size of the human foot. Too wide and they’d rub. Skaters begrudgingly increased the height and width and softness and rebound of the wheels until it was clearly demonstrated to be a winning combo. On super smooth ramps and concrete, you want a harder smaller wheel in the same way that you want the balls in your bearings to be steel and not rubber. You give up on traction but then again, you don’t need a lot of traction to land a trick or grind coping. That’s a different medium altogether.

Given gobs of high rebound urethane on a steep asphalt road and you can roll at over 85mph without a motor and start thinking more about better aerodynamics to go even faster. There are good reasons that no one is using a narrow inline wheel on a skateboard, even for going straight. They suck. If you like speed, traction, and control, go big, wide, soft, and high rebound.


The innovators dilemma… Much of what Chris postures about in a broad sense is discussed here by C. Christensen. (It’s a pretty good read I think, dated but timeless). Clayton discusses the disruption of industry using historical models and attempts to formulate why some business makes it though disruption and some don’t.

As for subjective or objective, in the sciences we break stuff up in to two broad categories, quantitative and qualitative. In the former we look for hard data things we can measure and repeat. In the later we might do a interview… If you get a big enough data pool (n1 (sample size) doesn’t mean a lot) both can be valid. It’s just: I did this once and this happened so… doesn’t mean much on it’s own except for a persons experience. Maybe this one person has cred, and a mass of experience so it might have marketing appeal. But that’s not science and we are blurring the two.

Thank you very much Mr. Chaput for your explanation but…

Yes, but we do have motors right?

Yes, but we are not talking about that kind of speed and again we do have a motor (or two :slight_smile: )

Ok, so two identical boards (same size, weight…) with different wheel sets and we let them go from the same hill at the same time… which one will go more distance?

Well maybe this is the reason that you have mentioned but thats my point and doubt here. Maybe there should be new approach to this? I belive that there will be more and more people like me who never ride a skateboard or longboard and eboard is totally different thing. For most users it is a way of commuting and that is going to be the mainstream. The industy is where it is and its easier maybe to adapt existing solutions than come up with new ones or maybe it’s a matter of scale at the moment? This is my DIY thinking not based on any science and not even on riding a longboard once, so I’m a bit keyboard warrior here but just want to understand :smiley:

Yes, electric skateboards have motors. And they have batteries. I’d rather have my motor taking small sips from my power source because I have very efficient wheels than taking huge gulps because of inefficient wheels, i.e. wheels with a lot of rolling resistance. What I’m saying is inflate your “normal”, narrow car tires to the right level for better gas mileage on asphalt, but if your in a dune buggy, don’t use highly inflated narrow tires. Skateboards are dune buggies. Ignore that analogy at your own risk.

What I’m saying as an approach is to do actual testing in real world conditions. Go to a downhill or street luge race and try to find hard narrow wheels without much rebound. Hit corners at speed on an electric skateboard and tell me how comfortable you feel on small hard narrow wheels. The difference is easily noticed.

And when the only difference between two boards is the wheels, and one board pulls away from the other from a dead stop AND has better traction and control and speed through the corners, which one do you want to ride? Better is better. It’s not rocket science.

Gravity is simply a different type of motor, and bad wheels hurt performance whether the force is gravity or the force is a brushless DC outrunner motor or a hub motor or a different direct drive motor. Most electric skateboarders will not go as fast as downhillers, but downhillers know how to design boards that are stable at high speed which means that they are safer and more stable at “electric” speeds. And believe me when I tell you that there are plenty of electric skateboard builders out there that are not at all content to be slower than gravity boarders. It’s like building cars that are beaten by a horse. A ONE horsepower horse. As we continue to go faster and faster, our wheels become increasingly important to us, and so are our trucks and bushings which are not getting a lot of attention right now. It’s a system, and you are only as strong as your weakest link.


How about this?

107mm 74a Abec11 Reflex thane, with a 63mm diameter hub for an R-Spec Hub Motor, would give 22mm of urethane depth. That would result in such a smooth and plush ride. I suspect it would feel similar to how good a soft Abec11 90mm Flywheel feels (22.5mm urethane depth). It would also cut down the weight (and cost) of the monstrous 107mm Flywheels

Best of both worlds. That’s a collaboration product I would buy in a heartbeat

@ChrisChaput + @onloop


@ChrisChaput Thank you for this info. Your core design is brilliant and I can see now why your rubber never detaches from the core.

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It’s not so much that I have a bad taste from the automotive engineer, it’s the abomination that he created, called a “next gen skateboard”, and then peddled to the unwitting public using engineer-speak and his company’s reputation as his marketing ploy. The board is a turd on wheels. Bad wheels at that. I’ve seen other who created these dual swing arm trucks and they were adamant about how they were able to keep their outside wheels in contact with the ground during a turn. They were doing all these desktop demos where a dollar bill slipped under their wheels was harder to pull out with their swing arms on. They never showed it compared to a normal truck, they never showed it under a proper load, they never showed it beating a different system, and they never showed it any “real world” conditions. It’s so frustrating to listen to a staged “win”. That whole concept was based on the idea that in a turn, most of the weight is transferred to the outside wheels as it is in a CAR. A car with a steering wheel, not a lean-steer vehicle. They were literally telling me that my outside wheels were experiencing as much or more force as my inside wheels. I asked them to explain how much force was on my outside wheels when I carved past them with both my outside wheels completely off the ground and they told me that I was just doing that to be a prick. Seriously, there was ZERO force on my outside wheels and they denied it was even happening.

I told that them that if you DON’T put more force on your inside wheels, you can’t and won’t turn in that direction. The simplest concept, but they had an agenda. To sell whatever they were making.

I had a HUGE financial investment in the original Flywheel hubs and wheel molds. I desperately wanted big cores with small amounts of urethane to function at a high level. They looked awesome, like a car with crazy big rims. But it doesn’t take genius to know what that tire feels like going over a pot hole. But even on smooth surfaces the big core and absence of unsupported urethane that could deform and stay in contact with the road meant poor traction. And OF COURSE we tried the cheap fix - to use super soft urethane in the hopes that it would be good enough. Nope. Not even close. We tried duros less than 70a, and marketed wheels in 72a. No amount of engineer-speak or marketing hype was going to make that wheel/hub ratio a viable high-performance contender.

At the end of the day, I had to bite the bullet, create a big, expensive, multi-cavity hub tool, and create a set of wheel molds for every different size. I was racing, and I wanted to win more than I wanted to make money. One hopes he can do both. And as the style of riding changed from controlled slides in the turns to pre-braking better and then “railing” turns, we moved to even smaller cores, wider wheels with more square and flexible lips.

It seems as if there is a big conversation of distraction that pulls away from looking at something at the heart of the matter here. We talk about windings and KV ratings and torque and “maintenance”, as if those are the only things that matter. What about the ride? I’ve never been able to put a thin band of urethane around big hard hub and have it feel good or perform well. I still own the big hubs and can make any mold I want. If speed is all that is important to someone, he can put some big ass motors on his trucks, slip some rubber bands over them and be happy. He won’t be able to stop as quickly which is problematic since speed is his thing, but safety isn’t the number priority for speed demons. He’ll be able to drift his back end well, especially on rough terrain because that back end be a-hoppin’. Tokyo drifters rejoice.

I am not anti-engineer. I am pro-reality.


BMW street carver is what you a referring to???

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but look at the videos. In the video from the hill climb on instagram the board was at walking speed and would have stopped eventually with the stock wheels. If you mount that much larger wheels on it the gearing will get even worse and it wont be able to handle hills…

Nicely said and thanks for the wheels. Been riding Abec 11’s for years and they’re the best f*cking thing I’ve put on my longboard.

I agree that with more thane, you get better traction and a smoother ride, but I feel like I’m able to get up to speed faster with my 72mm Freerides vs. my 77mm with less work. Once up to speed, my 77mm go farther and have a smoother ride, but it seems to take more work to get there. Why so?

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If I were to put my best guess forward here, the minimum wheel size for a 63mm hub motor would be about 111mm. In order for a fair amount of urethane to work efficiently, you have to bond it to a core of sorts - let’s call that a “sleeve”. The sleeve is structural, like the cardboard tube at the center of a roll of paper towels or TP. You don’t want urethane that can be pried up and away from that structural sleeve or core. A “mechanical lock” is that ring with the holes in it that goes around the hub’s (or sleeve’s) OD. It allows urethane to flow through it when the wheel is poured to provide an extra measure of protection should the chemical bond fail under a load. All of my wheels have cores (even the shortboard/street) wheels. All my cores are made in a material that provides and excellent chemical bond. All of my cores have one type of mechanical lock or another. Call these my “core values” :open_mouth: )

So, assuming that the wall thickness of the sleeve is 2mm (and that’s on the thin side), we’re essentially adding 4mm to the hub diameter making a 63mm hub motor into a 67mm hub. With an 111mm wheel as a starting point, you’d yield 22mm of urethane depth. That’s a little less than a 90mm wheel on a 45mm core (22.5mm depth), less than the 97mm wheel (26.0mm depth), and way less than the 107mm wheel (31mm depth).

But here’s the thing. You’ve heard me talk about the wheel-to-hub RATIO or the urethane-to-hub RATIO . Even though the depth of urethane may be a relatively big number, how does it relate to the size of the hub? Maybe 22mm of urethane depth feels nice on a 45mm hub but it may feel horrible on 90mm hub. When so much of wheel/hub combo is hub, it rides rough. Period. If it looks like you’re riding on the rims, it’s because you’re riding on the rims. I added a Kegel and a 111mm wheel on 67mm hub motor/sleeve so you can see some numbers. My experience is that the higher the number is in the rightmost column, the smoother the ride. I’d be interested in hearing if anyone else’s experience is different than mine. And last but not least, when I made my hubs narrower and allowed some unsupported urethane to deform and adapt to the road, life got better still. The hub in the first Flywheels went edge to edge. This is only desirable when we do 127mph and the urethane wants to pull away from the hub (seriously). We’re not there yet.


Yes, the BMW Street Carver is a “direct to museum” board that is never seen carving the streets for a good reason. It sucks.

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I suggest an objective test. You need to actually time yourself getting up to speed. When I’m on the freeway in a 1667 VW bus doing 65mph with the widows open (no A/C), I feel as if I’m doing 100mph. Vibration, wind, suspension woes, motor noise … it’s scary. When I’m in the back of a limo doing 100mph, I don’t even realize that we’re over the speed limit unless I look outside tinted windows and see us passing everyone. And I’m trying to focus on my supermodel and her twin sister. And when guys on street decks try to bomb a hill, they SOUND like they’re going fast and they do LOOK terrified, but speed-wise they’re crawling by comparison.

One test I’ve done in the past was to take a board with four (4) 77mm Centrax in Lime 80a Reflex and compared it to another board with six (6) 83mm Centrax in 80a Lime Reflex. One guy puts a foot atop one board and I put a foot on the other. While holding onto each other add the other foot, start to roll, and let go. We’d get up some speed, then foot brake and stop. We’d change boards, and do it again. Whoever was riding the 6-wheeler with the bigger wheels would always pull away from the guy on 4 smaller wheels. And you have to set up the 6-wheeler so that the front four wheels are perfectly parallel or you’ll build drag into the system. I heard a lot of people worried about the weight of big wheels. It is SO WORTH IT. Go on a diet if you want to lose a pound or two. High rebound urethane on the pavement is a GOOD thing, and you almost can’t have too much of THAT good thing.


In the end my main push decks have 77mm and 83mm wheels, so that pretty much says it all there in terms of what I ended up with. With the 72’s I had to push constantly which in the end took more work. Perhaps it felt like more work for each push because I had an extra 5mm more before my foot hit the ground? My main test was always the bikers on my route. Off the starting line, I did better with the 72’s, but the 77’s allow me to keep up. If there’s any downhill slope, there’s no competition. The bigger wheels with more thane blow the smaller wheels with less any day.

One of my friends told me once, “It’s a lot more fun to go fast in a slow car than fast in a fast car.”

I have to give you a HUGE high five for pointing something out that many/most people miss. When trying to perform a “scientific” experiment, you often want to “change only ONE thing” to better understand what caused the change in the results (if any). So someone might think that “only changing the wheels” is changing only one thing. Nope. You nailed it. You are also changing the ride height. And where the difference would be negligible let’s say “aerodynamically”, if you have to push that board around like a flamingo for long periods of time, you’re going burn your quads faster on that tall board sooner.

One thing that drives me nuts about skaters, okay, human beings in general, is that they tend to like to do something the way that it’s been done for years as if “there must be a really good reason for us always doing it that way”. So many times we do the things we do purely because of the cost, the convenience, the availability, or because you’re “safe” from ridicule if you do what everybody else is doing. For example, I think that we can all agree that electric skateboards and most all race boards are directional. There is a front and a back. They are different. Why do we put the same truck on the back as we do on the front? Does it really “not matter”? I think the answer is somewhere between “it’s easier” and “it’s cheaper” and “we don’t know any better” and “everyone else is doing it”. Argh.


Every little detail makes a difference.