Wheels & Tires
Rolling resistance
What does Rolling resistance mean?
The energy a tire loses as it flexes against the road. It rises in step with speed and weight, and falls with the right tire pressure.
Rolling resistance is the drag from a tire deforming where it meets the road. It is usually written as a coefficient, Crr, multiplied by the weight on the wheels. Wikipedia’s bicycle performance page gives measured coefficients of 0.003 to 0.006 for tires at their maximum recommended pressures, rising about 50% at 10 m/s (36 km/h).
How much does it matter?
At low speed and on climbs it is a big share of the effort. At 28 mph, aerodynamic drag takes over: in our model, rolling resistance is about 13% of the power needed. Correct pressure is still free speed. Start with our tire pressure guide, and see how to make an e-bike faster for the other drag checks.
Also known as: rolling resistance coefficient, Crr