What is Torque in an Electric Bike?

There has been a lot of discussion in the news lately about electric bikes and torque. For most people, the term “Torque” has little or no meaning.

In this first of 3 articles on torque, I will go over the basics of torque. In Part 2, I will discuss torque and how it relates to horsepower and then in the Part 3, I will compare the torque of Optibike and other leading brands of electric bicycles.

Why Torque Matters In An E bike

In an electric bicycle, torque is the ability to rotate the rear wheel. In a regular bicycle, this translates to the ability to rotate the pedals and crank arms. Higher torque will rotate the wheel easier and create more acceleration, especially from a stop. This means a bike with higher torque is easier to get going from a stop.

What is Torque?

The general definition of torque is the force on an arm at a distance from a center of rotation. In the picture below, the distance is 1 Meter and the force is 50 Newtons, so the torque is 50 Newton Meters.

Torque Equation

The general equation for torque is below.

Torque=Force X Distance

or T=F X D

In a standard  bicycle, the rider pushes on the pedal to create a “Force” and the length of the crank arm is the distance. Crank arms are typically 175 mm or 7 inches long. If the rider weighs 200 pounds and stands on the pedal, the torque is 1400 inch pounds as given by the equation below:

Torque=Force X Distance

1400 inch pounds = 200 pounds X 7 inches

Torque Units

In electric bikes, you will read about Torque in Metric Units (Newton Meters) or US units (inch pounds). You may also see torque in foot pounds.

A common torque for lower powered e bikes is 50 Newton Meters, which can be converted to 442 inch pounds or 36 foot pounds.

50 Newton Meters = 442 inch pounds = 36 foot pounds

In Part 2 I will discuss how torque multiplied by RPM make horsepower and how this affects your ride.