Thank you very much for your reply! That will make the gear drive more noisy, so I prefer going with 90kv motors that will also support up to 18s.
I will use 3dservisas gear drive wich comes in 1:2.6. I just lest wh/km to default values, I do not know how to calculate that. Do you know?
Battery and motors are more expensive than gears as far as tuning your setup goes.
On my 8" tire setup, I get on average 25 wh/mile which is 15 wh/km. Pushing it hard through the woods or rough terrain makes it go way up to 25 wh/km and beyond.
Iām also a pretty light guy at 155lbs
I also average about 25 wh/mile on 6 inch pnuemmies. Iām also light, but itās pretty hilly around here
This is a street board though
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I second this
Iām usually heavy throttling on my 6" pneumatic street board and get that so good to know.
@JulienB your urethane build will have muuuch better efficiency/lower consumption than the mtb as Iām sure youāre aware.
Thanks for all your input! Very informative! Yeah that is why in the end the urethane board will have the 12s4p battery.
also iām pretty sure most motors will handle whatever voltage you throw at them (amps cause the heat i believe) and i donāt think a higher gear ratio causes more sound, gear drives are hella quiet, itās when you use compound drives that the sound builds up
I am sorry to derail the thread a bit 
There is two reasons why this isnāt true. The first is that the bearings wonāt like to rotate so fast all the time, but this can be mitigated to a degree by changing them out with higher quality ones.
The second reason is that in the motor there are two kind of losses. One type is called copper loss, thats basically the energy dumped into heat because of the amperage and this is not influenced by the rotational speed of the motor. The other type of losses are the iron losses, and those are getting worse as the motor spins faster and faster. I have not seen any tests comparing iron losses and copper losses in esk8 motors, so I donāt actually know how bad iron losses areā¦ But they definitely exist, especially if you go with too high voltage and kv. The torque that the motor puts out is also a factor in the losses, but lets ignore that now.
This picture below showcases both losses for a random motor, obviously for the motors we use the numbers would change.
Sidenote, somewhere I read that the outrunners we use are the most efficient around 10k rpm. Probably thats the point where the losses are balanced out?
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I have tried to get the discussion about the āmagical erpmā limit going a few times but always end up getting āI believeā answers and assumptions with no data proving anything but a lot to think about.
Some discussion here Iād love to get kicked back up 
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tbh the motors we use are pretty damn small, and losses does not equal not able to use higher voltage. if you looking for efficiency the drive train should be the first place to look at.
I agree, but shouldnāt it mean more heat because of more losses?
due to the size of the motors we use the losses are pretty small. running higher voltage with a higher gear ratio would keep the motor cooler then a low voltage high amps (torque output the same)