Rolling resistance depends on the type of road, the condition, and the structure and performance of the tire.
(1) Impact of road type and condition. The rolling resistance coefficient of the tire depends on the road surface condition, which is 0.014~0.015 on the asphalt road and 0.3~0.4 on the soft soil road. On flat high-quality roads, the energy consumed to overcome road surface deformation and tread and road surface friction accounts for only 10% to 15% of the total energy consumed. On soft soil roads, energy is mainly consumed in the deformation of the soil. When the tire load and the wheel torque increase, the radial deformation and circumferential deformation of the tire increase, and the rolling resistance also increases, especially for the circumferential deformation.
(2) The influence of the structure and performance of the tire. From the tire structural parameters, the rolling resistance, that is, the rolling loss, mainly includes the tire type, tread structure and flattening ratio. The tread structure parameters of the tire also have a great influence on the rolling loss, such as reducing the thickness of the tread, especially the thickness of the shoulders, reducing the tread depth, the groove depth and reducing the dispersion of the blocks. Reduce the rolling loss of the tire. Tests have shown that for every 1 mm reduction in tread rubber thickness, the rolling loss is reduced by 1%; when the shoulder thickness is reduced from 14 mm to 10 mm, the rolling loss of the tire is reduced by 7%.
Rolling resistance is one of the important properties of a tire, which affects the kinetic energy consumption of the vehicle and the life of the tire itself. Reducing the rolling resistance can improve the sporting performance of the vehicle, and at the same time, it can extend the running life of the tire due to the reduction of deformation energy and heat generation. The rolling resistance can be identified by the rolling resistance coefficient or by the work required to overcome the rolling resistance for each revolution of the wheel. Rolling resistance is consumed by tire deformation, road surface deformation, and tire-to-road attachment. Therefore, the rolling resistance depends on the type of road, the condition, and the structure and performance of the tire.
Rolling resistance is the energy lost when the tire rolls. The main cause of energy loss is the constant deformation of the tire.
Of course, every bicycle tire should roll as easily as possible. Compared to cars, cyclists have only (very limited) physical strength and he wants to apply them as efficiently as possible.
In addition to rolling resistance, other resistances must be overcome when riding a bicycle:
As the speed increases, the air resistance rises in a square ratio. Air resistance has become a major resistance at an approximate speed of 20 km/h on the ground.
Acceleration energy is also consumed. For example, when the mass has to be rotated, the weight of the wheel is very important.
The main resistance to overcome when going uphill is the gradient resistance (slope resistance).
In addition to this, the chain and other rotating parts have other frictional resistance. However, in a well-served bicycle, these represent a small fraction of the total resistance.