When will a motor move you?

since the whole esk8 thing started, almost everyone is using a longboard with motors of 50 or 63 diameter.

but the real question here is, a nearby project i am thinking of building an electric skateboard (not the longboard). so 50mm wheels or smaller. a normal standard skateboard.

it should not be fast, it should be easy to carry, lightweight and it should move me.

so mechanics and stuff is not the problem, but i am concerned about the motors - so here is the question.

how can i find out which is the smallest possible motorsize i can use? sure the gear ratio also plays a role but this i can change. so 30 in dia? 35? outrunner?

i think 15-20km/h is the perfect and comfortable speed to move for citys and stuff.

50mm wheels will be extremely hard to do, and it may not be possible at all. You will have to use tiny pulleys, and the motors won’t have a lot of power either. Another problem will be the kv of the motors. Its very hard to find a 3542 (for example) motor with a kv lower than 1000. Which is obviously waaay to high for our needs. These are just some of the problems you`ll have… To be honest I dont really see the point of electrifying something with smaller wheels than 83mm, but that just me…

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this is why i am asking here, i am playing with that thought, what if the gearing ratio is very high and then the kv from the motor shouldnt be a problem, or not?

Alien power systems might have motors of that size

Maybe this work for you or you use hub motors

Thats the problem… You can’t really go lower than 10t on the motor pulley. And if you want 20km/h top speed, you will need an 80T pulley on the 50mm wheel (6s 1000kv setup), which obviously doesn’t work…

what about a direct gear drive?

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You mean direct drive? Lets say you use the motor linked over (4260 300kv), then you`ll have 4mm of clearance to the ground… And the kv is still waaay too high, unforntnantly

I do not recommend you to use so small wheels, you will end up replacing them… But if you insist then I recommend you to use HTD3 gears and belts instead of HTD5…you will have more room for different ratios, but you will loose some torque transmission… I think you will be able to squeeze 50mm motor , as far as I know there arent any mount for 42mm motors, so you would have to make one yourself :confused:

I would go for 270kv 5065 motor with 15/36 15mm HTD3 belt drive with 6s Battery…if you want more power you would have to place second motor diagonally (on the other truck) (Calculations)

Problems you might notice: YOu will have to make your own pulley for the wheel…I mean making your own holes in bought pulley and wheels…the wheels wont probably last long…

Be prepared that you will have to modify your trucks for your custom motor mount and to fit the pulley…Hope you have experience with making stuff :slight_smile:

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If having done your physics homework you have been able to find out how much force it would take to pull yourself from resting. Gearing it easy peasy once you know that first number.

Also if you want to make your life easier, and you dont want to drill in your wheels you can buy roller skate wheels like these (arent they sweet?) because they have holes in the core, that would make your life easier, you could just 3D print the pulley and go :wink:

I have never ever seen anyone do that, so it would be funny :smiley: :smiley: :smiley: I dont see reason why it wouldnt work :smiley:

I dont know about any skateboard wheels with holes in core, which are as small :confused:

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@Acidfie said “gear”, so he does not mean direct drive. Direct drive would either be hub motors or inline motors like Carvon.

Yeah, i tought so too, but there is alot of confusion around the forum about what «direct drive» really is… So its kinda hard to tell what a person mean, if you dont know him/her.

There is no confusion, it’s all spelled out with a quick search. Gears are not direct drive. They might be gear drive or cog drive or a transmission, but they aren’t direct drive. That’s what hub motors and inline motors are.

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I know that when gears are involved, its not a «direct drive», but there is alot of people around here thinking that it is

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its geared, so still you have the chance to use 3 gears.

still, the question ist how much torque do i need to move a human beeing on the board.

saw this page here CLICK

it says, about 200-300 watts, so i think 2 outrunner should do the job with the right gearing, or not?

As I have mentioned earlier its not the power that will be the limiting factor in the first place, its the whole Kv/V/Gearing/50mm wheels. If you can find a 40/32xx motor with a kv of around 100, then maaaybe… But you likely won’t, because they dont exist as far as I know. Also the riding performance won’t be any good with such small motors.

whats the matter with the kv? still i think a motor with about 500-800 would be powerful enough if it will be geared up enough. motor turns faster but is geared down

Yea, up to 7mph. You lose a lot of torque the faster you go, and torque bottlenecks your power.

did you just calculate this? still i think 10 km/h would be enough for such a cheap build, since it moves me faster than walking