Stop using the traditional method to calculate the gear ratio. There is a new one to figure out the correct gear ratio!


Let’s check out this essay now!

Stop Calculate Gear Ratio! Using the Distance to Figure out the Correct Gear Ratio!

This topic is not be concerned in the plastic tire. There had differences between the tries (wheels) size made by different factories. It is important of us to define how to figure out the correct gear ratio!

For the recent popular m-chassis car, the differences of tires (wheels) between m-chassis and 1/10 can be around 10mm.


Left: Xpress M-Chassis Tires (Wheels), Right: Xpress 1:10 Original Tires (Wheels)


Even same car type, There has a bit difference of tires (wheels) between different brand.


For defining a correct gear ratio and car speed, we need to consider all variable of tires (wheels) in the calculation. We need to calculate the moving distance of the tires goes once.

There is an app to help you figure out the ratio in a simple way.

Application: To calculate the moving distance of the tires (wheels) goes once

Assume we are playing a 1:10 touring car, the gear ratio is 5.97 and the internal ratio is 1.9.

If we want to change the  gear ratio into m-chassis


Left: 64mm Tires (Wheels) diameter, the moving distance is 33.7mm when the motor goes once

Right: 56mm M-chassis Tires (Wheels) diameter, the moving distance is 29.5mm when the motor goes once

Result: In the same gear ratio situation, the 56 m-chassis tires (wheels) is shorter around 4.2mm, compare with 64mm Tires (Wheels)

Application: To calculate the same moving distance 34.2mm 

To make the Gear Ratio faster, we can use a smaller SpurGear (T) or bigger Pinion (T).

Example: Increase the Pinion (T) from 35T to 40T to achieve the same moving distance 33.7mm


It is so simple!

If we use the M-chassis gear ratio into the 1:10 touring car, it caused the car speed too fast. The motor may out of control and damage.

Using a bigger SpurGear (T) or a smaller Pinion (T) is a best and safest choice to reduce the power, it can maintain the same moving distance.

In addition, this app can calculate

– Internal Gear Ratio
– Finial Gear Ratio

Application: To calculate the internal gear ratio

We need to know

  • Diff. Pully (T)
  • Central Pulley (T)

Refer to the below photo,  it shows how to calculate the internal gear ratio (if you already know the internal gear ratio, you can directly input)


If you already know the internal gear ratio, you can directly input


Application: To calculate the Final Gear Ratio (How many times of motor turn when the tires (wheels) goes once)

We know to know

  • SpurGear (T)
  • Pinion (T)
  • Internal Gear Ratio

Refer to below photo, it shows how to calculate the final gear ratio


Download RC Gear Ratio Calculator by clicking this link


This app is designed by R/C car fans ! it can easy to calculation …..

  • The motor rotates once moving how much distance(Rollout)
  • Final gear ratio
  • Internal gear ratio

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