esk8.news esk8 calc donate now

Torque Vs Speed - How Much Do I Need?

Here we discuss torque vs speed and a bit on gearing
First we all need to understand what Torque and Speed are so i made a little definition that everyone will relate to

Credit to @High-roller for the GIF

On some esk8 Calulators like this one, they calculate Torque, which is expressed in nm (Newton Metre).
To make this as simple as possible for noobs and learners alike, i will be using nm in examples to get a better understanding but remember this is rarely talked about in this form.

Lets start with basics.
You can’t have more torque and more speed. A compromise is always needed.
Torque/Speed can be changed either by changing motor pulley or motor (kv). Speed may be changed by having more batteries in series (a 12s will have a higher top speed than 10s.
The lower the t (teeth) on the motor pulley, the more torque.
Example (10s) :
a 14/36 ratio will give you a good amount of torque but low top speed
a 18/36 ratio will give less torque
You may also change wheel pulley but that is more troublesome and expensive so no point doing that.

Most people use 15t motor pulleys as it is a good balance between top speed and torque
Example:
10s - 107mm wheels - 15/36 ratio - 190kv motor dual
= Max speed of 67km/h unloaded.
You must play around with your wheel diameter and the calculator to find what is best for you.
Please note if using a Belt Drive do not use a motor pulley below 14t as slippage will occur.

Torque
A Trampa mtb board for example with
6364 160kv 2400W motor dual | 13/66 ratio | 225mm (9’’) tires |
this is Tramp’s best belt driven option for hill climbing abilities and will give you
17.3 Nm of Max Torque and 51km/h top speed loaded which in my opinion is the best of both worlds.
Note that 13t is because trampa have a special belt drive system to allow such low teeth on the motor pulley.

Now let’s take a look at a typical hybrid build nowadays
6374 190kv 3150W dual motor | 62/15 | 160mm (6’’) tires |
This setup will give you 15.5 Nm of torque with a top speed of 52km/h loaded.
Here is a good graph from @Pedrodemio

After all that we also need to understand that these are a theoretical side of things and if your Vesc can not give the oomph needed then the results change. Using a vesc that can only handle 25A per motor won’t do you much good getting you uphill. If you want torque/speed, you need a high-end controller. A controller with at least 60A per motor will be sufficient.
In the end you see there is little difference and given a standard set up is almost comparable to a mountain climbing machine like Trampa board, the difference comes down to type of wheel, wheel diameter, gearing, motors, at whole bunch of super complicated maths to go with it that I will let @professor_shartsis explain if that is what seems to help you.

In the end, it depends on what you want to build and type of terrain, etc… experiments must be done with the calculator and if you any questions post them below.

If you want a quick summary of what you need for torque

  • Dual 6374 (or bigger!) motors
  • A gearing geared toward torque ( this applies for all builds as more torque is better than more speed in most scenarios)
  • A good solid battery so you can have tons of fun!!

If I have missed something let me know and I will add it in

7 Likes

i am speed


thanks for coming to my ted talk
xoxo

7 Likes

Enough to be able to go up majority of inclines in my area. Anymore than that, can be plopped into gearing for more speed. But due to speed limits in my country i’m all about that 14/44 pulley ratio.

1 Like

I said this in another thread but I’ll say it here.

No point in having speed if you don’t have enough torque to make it worthwhile. It’s no fun to top out at 40 if it takes 60 seconds to get there. Plus you gotta stop eventually too and torque helps with that.

8 Likes

torque > speed
but both is best :slight_smile: (with bigger motors/settings)

the ratio between the wheel torque (newton meters) and the wheel radius (meters) determines the thrust (newtons). a 1 meter radius wheel with 14 newton meters torque has 14 newtons thrust. a 0.5 meter radius wheel with 14 newton meters torque has 24 newtons thrust, but half the ground speed for the same angular velocity (rpm or rad/sec) etc.

the motor torque is mutiplied by the gear ratio to get the wheel torque, for example 7 newton meters motor torque with a 2:1 reduction gives 14 newton meters wheel torque, but the wheel has half the angular velocity as the motor.

the motor torque is determined by a complex ratio between the kv and the motor current (lower kv gives more motor torque per motor amp, but less peak rpm per volt).

5 Likes

Why not both yall?

I ain’t giving up shit for the other

1 Like

If you target a reasonable top speed, like 30mph (48km/h) then generally you want as much torque as possible. Use the calculator

3 Likes

you trade one for the other… in a particular case, this chart shows the difference in thrust between 100mm and 120mm tires:

^the 120mm with higher top speed has less thrust / acceleration

1 Like

I don’t think you’re getting my point, what I’m saying is that why not have enough torque to do standing burnouts and also hit 45 mph easily? Why want one over the other

2 Likes

you might be beaten in a race by someone who is geared for 50mph but can’t do burnouts…

4 Likes

Id like to see that

On this topic, a big thing that is missing for me on VESC is acceleration limit, lets say you have 25%+ inclines that you want to climb without losing speed, for that you have to have power and torque, but this make the board fairly aggressive on flat ground

2 Likes

on a 12S dual motor board geared for around 34mph no load speed (32mph or so top speed), 60a battery limit per motor will get you up just about any hill without losing any speed

3 Likes

@Pedrodemio @professor_shartsis i have added that in

1 Like

Can we get this for 10s? I get that its just more amps, but a graph would sure be nice =’)

1 Like

Thanks for the credit man, though I’m pretty sure that on the internet nothing is original these days. I forget exactly where I got that from.

Nooo, say it ain’t so!

I’m afraid it is kid.

Your summary seems to be pretty spot-on. I will add regarding the gearing that if you really want to not worry about torque a don’t care about speed almost at all get the biggest ratio your wheels can fit, 1:5 or better if possible. Unless you’re a very hefty dude this I think is the one thing that will make the most difference (up to a point).

1 Like

Torque all day. Speed is a bonus. 4wd for the win.

1 Like

I have been rocking 20/60 on 6" wheels 13s. 170kv.

It has goood torque, but still ass puckering speed as well…

3 Likes

10S, 2WD:

12S, 4WD:

1 Like