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.
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