Rolling Resistance Calculator
Find the rolling resistance force on a wheel.
Rolling resistance is the force resisting a wheel rolling on a surface.
How the Math Works
The rolling resistance force on a wheel is calculated using the formula F = Crr multiplied by N. In this equation, F represents the rolling resistance force in newtons, Crr is the dimensionless coefficient of rolling resistance specific to the wheel and surface materials, and N is the normal force in newtons exerted by the weight of the object supported by the wheel. This linear relationship means that for a given surface and tire type, the rolling resistance increases proportionally with the load on the wheel, making it a straightforward yet powerful tool for quantifying energy loss due to rolling motion.
Practical Applications
To use this calculation practically, first determine the appropriate coefficient of rolling resistance for your specific wheel and surface combination from manufacturer data or reference tables. Next, calculate the normal force by multiplying the weight supported by that wheel by the acceleration due to gravity (approximately 9.81 m/s²). Finally, multiply these two values together to find the rolling resistance force. Engineers use this to optimize vehicle design, cyclists select appropriate tire pressures, and manufacturers specify motor requirements for wheeled vehicles to ensure adequate performance.
Day-to-Day Use
Understanding rolling resistance helps explain why your bicycle feels easier to pedal on smooth pavement than on loose gravel, or why fully inflated tires roll more efficiently than under-inflated ones. This knowledge allows you to make practical decisions like maintaining proper tire pressure for better fuel economy when driving, choosing appropriate tires for your vehicle and driving conditions, or understanding why heavy loads on trailers or trucks require more fuel consumption. It also explains why certain wheels or tires are recommended for specific applications, from racing bikes to heavy-duty industrial equipment.
Worked example
Crr 0.015 on 1000 N → 15 N of rolling resistance.
FAQ
Why are bike tyres pumped hard?
Higher pressure lowers Crr, reducing rolling resistance.