### Calculating speed by rpm and wheel diameter

Click here to jump to a calculator at the bottom Calculating the speed of any machine is quite a simple task if you know the diameter and revenues per minute (rpm) of your motor or other power source spinning the wheel. Other variables might be gearbox or other rpm transitions between motor and wheel, for example, bicycle gears. For those, you need to know the gear ratio. Gear ratio In this example, we have an electric motor that has a maximum rpm of 5000. The motor is a rotating gearbox with a gear ratio of 64:1, which means the gearbox will lower down the rpm by transforming the rotation to one time for every 64 revolutions of the motor. Formula to calculate rpm after gearbox motor_rpm / gearbox_ratio In this example: 5000 rpm / 64 = 78.125 rpm Wheel diameter For this calculation, we will use a wheel diameter of 220 millimetres (mm). To get the speed, you need to calculate the circumference of your wheel. This can be done by using π (Pi) value, just multiply your wheel diameter wi