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 Calculators 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.
Let’s start with the 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
an 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
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.
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 (V)ESC 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 big solid battery so you can have tons of fun!!
This is now a Wiki. Please feel free to edit to clarify/enrich this thread!