Sprocket Selection

Most Personal Electric Vehicles use a one speed gear reduction. With only one speed it is important to get the gearing right. If the gearing is set for to high of a top speed the motor will not be allowed to turn at its optimal rpm and efficiency will be lost. This loss of efficiency is due to an increased amp load on the motor from the improper gearing. Improper Gearing can lead to poor range and motor over heating.

An example of a standard gear reduction is 6 to 1. The first number in the reduction refers to the drive gear that is attached to the motor shaft. The second number refers to the driven gear which fits on a specific vehicles wheel. This ratio number will very greatly depending on the RPM of the motor, voltage, size of tire and the desired top speed,

A 6 to 1 gear reduction means for every 6 times the drive sprocket turns the driven sprocket turns once.

Calculating top speed.

The long mathematical equation below can be used to calculate the top speed of an Electric vehicle.

Tire Circumference in inches (( Width / 25.4 * Aspect Ratio / 100 + Rim Size / 2 ) * 2 * PI) x (RPM / Primary Drive Ratio * Gear Ratio / Final Drive Ratio) x 60 / 66360

If you do not want to do the math, we have made a handy gear calculator you can be downloaded by clicking below.

Gearing Calculator (Single Reduction)