Wow. I’m surprised to hear such harsh words from such an intelligent person, when you haven’t even tried the best of hubs on the market today. These hubs have changed the game. Things are not the same anymore.
It hurts to have the person you respect and admire so much rip apart the research and development that I and many have done for the past two years. These small hub motors are novelty. But even pushing these new larger hubs hard now, I can not make then overheat the same way. There’s always more to learn and more innovation to be done. If your try a pair of any of these three motors, you’ll see that we have the space to fit a stable motor into the wheel, that won’t overheat, even when pushed a bit.
I’m willing to concede and say things that aren’t in best financial interest, such as conceding that belt drives have an advantage that hubs never will be able to fully utilize. But to go as far as to say they are “novelty” is insulting and it’s clear your trying to protect your business. It’s sad, because if you tried my board, as is now, with 4wd hubs, you’d be pretty happy with the torque and the max temps the motors get to.
I wouldn’t get too butt hurt about it, I have been pretty open about my assessment of hub motors. They are just too big a compromise for me on several levels.
Novelty is key to having a successful product so take it as an insult if you like but it does not change anything. If it were not for novelty none of the Chinese manufactures would be producing them.
@evoheyax Until hubs are available, that ride plush, like abec 97s or 107s or can perform exactly the same as satellite set ups (trails/steeps or with pneumatics) they pretty much are a novelty. Popular yes! And if you poll it, or ask publicly the concensus for popularity is going favor hubs because of aesthetics. I suppose somebody needs to make a 70mph belted set-up to sway the masses?
Care to trade a dual set of your best hubs for one of my Dual Drive systems with 97’s? We could do a “Same Thread Forum Comparison”
I dont think this question was answered by Chaka, maybe because there is no good reason. How would a belt drive using 4.12 VESC even hit 40-50mph? With 12S voltage, a 190kv 14P motor, a 2:1 gear ratio at 85% efficiency and 90mm wheels it isnt even breaking 40mph and is already at the max recommended erpm limit of 60k.
I made the following statement.
Here’s a model that would test this idea.
Two eboards, both with 10S batteries, same vescs settings with 90mm flywheels maintaining a constant speed of 30mph.
Board 1: 2:1 belt drive and a 220KV motor
Board 2: 110kv Carvon V3 direct drives(not quite hubs but close enough).
@chaka Can u argue that a belt drive is more efficient under the above circumstances? Both motors are spinning at 80% of their max rpm, but belt drive has additiinal frictional losses from the belt and higher energy loss within the motor due to double the motor speed. Where is the hub motors disadvantage at cruising speed?
This reminds me of when my grandfather told me automatic transmissions would never compare to the efficiency or reliability of a manual gearbox. Now 20 years later, less than 3% of cars in the US are stick shifts.
As a general statement what you said is just plain false. U cant build build a 2000w belt drive that will match the performance of my 4000w hub board. Please do show up to performance day next month and try your luck if its worth it to you. If your 2000W board can beat my hub board in both a 50m and 100m sprint Ill pay your airfare home. Im guessing your board wont be sensored either since you said earlier this week that nobody needs them and their just another potential problem.
The only way I can see your statement above as even being close to true would be for a hub board and belt drive board with the same KV motors, but for two boards with the same topspeed your belt drive needs double the KV which cuts your torque advantage in half and increases your motors heat production as well.
Thing is, There is nothing that states we can’t run less reduction. We can run it all the way down to 1:1 with belts. And we can change kv’s. We can make a 1.5:1 4wd build @200kv@10s on 107’s -64mph weighted/fully charged
I’ve always been curious where the inefficiencies in hub motors were coming from and at the time it seemed to be kV. Now all the hubs being produced are lower kV and many are still inefficient which lead me to believe heat was the culprit. I think Jason proved that they could be just as efficient with the Raptor 2 if they can dissipate all that heat.
Easy there big guy, no need to pound your chest. I was talking about apples to apples, identical motors on different drives. To argue that you get better low end torque using taller gearing doesn’t make any sense.
@NickTheDude From my understanding, the trouble starts by adding more turns to the stator windings to decrease the KV. Alternatively you can increase the number of stator teeth to lower the KV. By increasing the number of stator teeth you can effectively lower the kv without adding more turns. I assume this is why we see a higher number of stator teeth in hubmotors today. I could be wrong here, I still fall back on the engineers at the factory for these things.
The word novelty implies that something has little to no practical value. The fact that these new round of hubs aren’t having the overheating issues of the past, and are riding decently smooth (have you ridden a raptor 2?) shows practical use. Belts have their own uses, and unlike everyone else here, I’m not trying to say hubs are better or belt drives are better. They both have their uses.
I could argue the same about belt drive systems. To me, belt drives are a novelty and a nuisance. Aligning, tensioning (except for idler systems like chakas), and the space that could be used for more electronics if your bottom mounting (which most of the diyers are doing). They were so impractical compared to hubs for me, that belt drives are a novelty. Not practical for the masses or for most diyers. Too much of a pain and complication. Hubs are simple, but unless your invested in hubs, theirs no reason to admit this. And since theres no good hubs on places like alibaba, you don’t have much of an entry into hubs, unless you start from the beginning and build your own. So the easiest thing to do is call them a novelty. Until these recent round, they were, but the game has changed.
Totally agree here. They aren’t perfect yet. But they are progressing so fast. As it is now, between enertions raptor 2 motors, hummies motors, and the carvon 3 and 4, you can get mostly everything you could every want. High top speed, low top speed, full abec wheels, off road wheels, you name, it can be done with one or multiple of these motors.
To some degree, yes. More turns means more copper length, which means higher resistance. Higher resistance = higher heat. This can be solved though, by making the motor larger. We have cut resistance from 0.138 ohms down to 0.068 ohms by doubling the stator length, allowing for a thicker gauge wire and less turns (15 now instead of 30 for the same kv). So yes, we can engineer our way out of the problems hubs have faced. They can be sustainable. And this is still, far from a full copper filling on the motor too. Can do a 19 awg I believe, and reduce the resistance even further.
I agree that belts are more versatile in that wheels and gear ratios can be quickly changed. Theoretically you could even overdrive your belt set up, but as u approach the 1:1 ratio you lose all the torque and efficiency belt drives claim to have over hubs. I dont think a 2:1 belt drive board with double the KV has any real torque advantage over a hub board with half the KV. I think both boards would accelerate similarly and have the same topspeed.
@chaka
I might have pulled your statements slightly out of context, I might also have been trying to incite some friendly rivalry to inspire you to join us next month .
When did I say taller gearing means more torque?
Well apples to apples the hub board is capable of twice the top speed of a 2:1 belt drive. So what u gained in torque you lost in top end.
Cheers,
From the 300lb guy with the fastest Vesc powered board on the forum .
Could we not double our motors from 2 to 4 just like you did to get the torque you wanted with your hubs? Doing that, we can raise our kv to get the desired top speed while maintaining our torque. That was what I was trying to convey.
Totally, but the erpm limit is a bit of an obstacle for gear reduction boards trying to break 40mph. Youd have to run very low gear ratios or switch to a different esc( rc or vesc 6).
A 3:1 ratio on my race day board netted 33mph with 2 motors @40a. So I’m pretty sure I could drop my ratio to well under 2, double my motors to account for the loss of low end torque, up my amps and allow you to go 60mph on my board.
Sounds feasible, but youd lose almost all your torque advantage and your motors would get much hotter too. So what real performance advantage does a high speed belt drive have over a high speed hub drive? Seems pretty comparable for boards that go faster than 35mph with the current erpm limit. If youre running the VESC 6 then I think gear/belt drives get the advantage back since 300+ kv motors are possible and you can keep you 3:1 and still hit high speeds.
What Id really like to see is how torque compares on belt drive and direct drive compare that are set up for the same mph. Im not saying saying that the hubs would have more torque or vise versa, Im sayng that I dont think there would be much difference.
@evoheyax these belt drive dudes are never going to concede, even if video evidence & engineering literature is furnished proving many of their arguments to be invalid.
FACT: When applied to esk8 use case, belt drives also have engineering/[erformance constraints that cannot be overcome easily.
The only option left for anyone looking to push the envelope is an improvement in motor design! Understanding how to improve the efficiencies & performance from inside the motor itself is the holy grail. @evoheyax this puts you ahead of the rest, anyone who doesn’t talk about motor design from now on is not a real threat.
REMINDER: Torque transfer of common 5mm pitch belts are a bottleneck that cannot be removed easily. You need wider belts. More teeth in mesh, Or no belts.
ANOTHER INTERESTING FACT: If I put an R2 motor on a >=15mm wide belt, with appropriate teeth in mesh, maybe an idler (which reduces belt duty cycles) you could theoretically (assuming the transmission can handle the torque) have more torque at the wheels than the standard R2 HUB at 1:1, but it would be just ridiculous… nobody actually needs that!!
More torque is no longer the objective here!
More efficiency is the new kid on the block in esk8 innovation. If you regard yourself as a legit esk8 builder & you aren’t spending money doing R&D to improve efficiency (whilst preserving/improving torque) you have already lost the game.
True story! Not a single full hub motor yet with good power has solved this completely. Its comimg though. @evoheyaxyour urathane cores are up to the task but Im still skeptical.
Describes what we have been doing the past 2 years exactly. The new double wide hub motors increased torque significantly, while decreasing heat significantly. Just tested it on some 20% grade hills, did laps for 15 minutes up and down. Max temp was 151 F on one motor, and 130ish F on the other 3 (maybe a short, idk why one was so much higher, since they are all the same kv. We’ll find out in time I guess). Pretty good, when the old motors would have hit 160 F in the first hill climb. I think I climbed it about 20 times, back to back. And it’s a long block.
And we understand pretty much everything (except for the real cost benefit of 24 teeth instead of 12. Might have to get the 24 tooth stator of our current stator and see what happens) about how to increase efficiency, and in tern, lower heat
your urathane cores are up to the task but Im still skeptical.
