The calculation of the final drive ratio of the RC car is...
[No. of spur gears x No. of Pinion gears x Secondary gear ratio]
You can calculate with the above.

It is very troublesome to calculate every time, so I developed this application which can be used offline.

When set to low gear (high numerical value),
- Acceleration (rise) is fast.
- The maximum speed does not increase.
- The motor load reduces.
- The running time of the batteries will be longer.

When set to high gear (low numerical value),
- Acceleration (rise) is slow.
- The maximum speed increases.
- The motor load increases.
- The running time of the batteries will be shorter.

However, please note that some motors and ESC have their own recommended gear ratios.

I hope it will help you in your RC car life!