Why not use gears instead of belts and pulleys?

No worries lol, I’ll message them tmrow to see if they are will to show me some cad :slight_smile:

That’s not true. Unloaded it can be true. But add load and your watthour/mile will be drastically different with different reductions.

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if a controller has no erpm limit, then for a given stator & copper volume, the higher kv motor can produce more mechanical power for the same losses, making it more efficient.

by adjusting the gear reduction ratio, you can select the ground speed at which the motor produces peak mechanical power, and generally increasing the gear reduction ratio improves efficiency.

the high rpms at which a high kv motor outputs its peak power might not be suitable for a direct drive / hub motor without some gear reduction.

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By efficiency I mean the literal efficiency of the system, you are not loosing any additional energy to friction (excluding extreme cases where you change the weight of a gear dramatically in which case it will become less efficient). The point is if the rotating mass in a 1:1 ratio system is 1lb and the same is true for a 2:1 system there will be no efficiency difference. In terms of watthour/mile then you can only really come up with an estimate you are happy with unless you want to put a transmission on your esk8, a higher reduction has a much higher efficiency than a lower reduction at low rpms, however the lower reduction will be more efficient at higher rpms

Absolutely, changing a gear ratio only changes the most efficient rpm or speed to ride at

here’s some info from a different thread:

^take a look at the green line, top left chart (electrical to mechanical conversion efficiency %), the only thing changing between steps is the gear ratio.

notice the lower the gear reduction, the lower the conversion efficiency for a given speed.

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Devin that’s you?

Shartsis, let’s say we have identical size stator, and copper volume motor and same kv, let’s say 100kv. One in a direct drive and another in a reduction setup. The DD will have a better electrical to mechanical energy conversion than a reduction setup because there is no transmission and losses due to that transmission.

here’s a comparison of 100kv, 2:1 (belt reduction) vs 1:1 (hub)…

(50v battery, 50a motor limit, 50a battery limit, 0.05ohm, 100mm tire)

if you take a look at the green line, top left chart, the 2:1 gets an increase in electrical to mechanical conversion efficiency. (more mechanical power at a given speed for the same losses)

Well thats only if the wheel is mounted directly onto the motor, if you have a 1:1 ratio using gears you will be loosing the same amount of energy as you would with a reduction. Also the losses are negligible because the point is to increase the torque of the motor.

All this calculated nonsense does nothing for the real world. Not every road is flat. Your not always going to be going the same speed for x distance. Not every street is long enough to get up to or continue that efficiency speed.

You can calculate all day long. But if you have two boards exactly the same, with different reductions. The higher reduction is going to have better efficiency all around. Because it’s more then just X speed. It’s the stop and go.

So theorize all you want. Tell me when you have some milage under your belt and have tested real world range with the same board and different reductions on the same setup.

/I’m out lol

@Deckoz Yes, in the real world you will additionally have to contend with iron losses, esc losses, battery losses, drivetrain losses, rolling resistance, grades, all of which will reduce top speed, thrust & efficiency compared to what the chart shows because it doesn’t factor these losses - that said it does give comparisons which are ballpark-accurate and mostly in agreement with other motor simulators and esk8 calculators because the losses which it does factor (wind drag and copper loss) are generally the largest in magnitude.

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Just for the record. My comment was towards @EverBlade21

@professor_shartsis I think for once you and I are arguing the same point with different words. As esk8 isn’t a static simulation.

We can calculate this all day long. But in the end, the only numbers I’m going to believe are your watthour/mile. Go test different reductions for yourself on the same board @EverBlade21. Get 4 or 5 charges in so you can get an average wh/mi on that reduction. Then repeat with a different reduction. Your numbers are going to be vastly different. No matter how you calculate it on paper.

What/Which/Whose wh/mi statistic do you believe? You can drive easy or hardcore. The wh/mi will differ a lot.

You cannot really compare the same Setup only one Motor has a 1:1 and the other a 2:1 reduction. They are set up for a completly different Speed! the 1:1 Motor Needs, lets say, 30A at 30mph but the 2:1 Motor never gets to this Speed. How can we compare it? …

we should rather compare 200kv Motor 2:1 vs 100kv Motor 1:1 (or Wheel Diameter…)

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Pretty simply. You aren’t always going 30mph. Riding is alot of stop and go. The question is which one has an more efficient pattern of getting up to speed with less current from a stand still repeatedly?

Calculating for static speed doesn’t mean anything.

If you took other threads that take averages based on paper calculations my Evo would only get about 30 miles of range. Yet I get 40-44miles. Because calculating for static speed doesn’t give you real world stop and go. The most amount of energy is wasted when accelerating your mass.

So instead of looking at a static speed calculation. Take all the static speeds out. Make a graph with ten to twenty repetition of 0-15mph or whatever end speed you want. And add up the energy used from those numerous stopped to speed ramps. Then do the same with a different reduction. That will give you a closer to real world example then calculating a static speed usage.

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I like that style more! Now we are going the right route!

PS: the static Charts are helpfull too but they are not adequate for a Performance comparison.

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Me too. It’s the only thing that makes sense if you want something comparative to real world. Static is just so vague :slight_smile:

We just Need large data of wh/mi from different Setups. i mean logs from real world Tests :smiley:

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While I agree… in order to compare something you need the same rider so accelerations style and weight stays constant. I’ll do a couple logs once I get my mini drive from kugils. As I’ll have 2.4:1 and 2.8:1 Spurs. My Evo is currently on 2.4:1 belt driven and I average 9-11wh/mi. I’m of no doubt I could likely hit 50+ miles on 2.8:1 because of the decreased load/increased leverage.