Construction of the tire.
The bicycle tire is composed of two parts: an inner tube which ensures that the air remains in the tire and the outer tire which allows for the driving performance.
The outer tire is made up of two bead wires (b) , the carcass (a) and tread (c) . The bead wires ensure that the tire remains seated in the rim. When the tire is inflated, the bead wires are tightly pressed against the rim causing the tire stays in place. The bead wires usually consist of steel wire. In order to fold the tire and become lighter the tire bead wires are also made of aramid fibers.
Tires with steel bead wire should preferably not be folded. Optionally, they can be folded into three loops. Tires with aramid fibers can be folded into a small package. Ideal to carry and lighter than a tire with steel wires.
The carcass is composed of fibers that are smoothly connected by rubber. As fibers are cotton, silk (for lightweight straps), nylon and aramid fibers used.
The various layers of fibers are referred to as cord layers.
The carcass is there to make the bicycle tire sufficiently strong.
The carcass must be able to withstand the great pressure which is applied in the bicycle tire.
Case of cylindrical objects that are subjected to pressure is the strength of the cylinder depends on the tensile strength of the material, the wall thickness of the cylinder and the diameter of the cylinder.
The smaller the diameter of the cylinder, the greater may be the pressure in the cylinder.
The strength of the bicycle tire is therefore determined by the tensile strength of the fiber material of which the carcass is made, the quantity of plies in the tire and the diameter of the tire.
Bicycle tires of road bikes are narrow because they are stronger as a result.
They can be inflated and reduces reliance plies in.
A tire with low ply is light and has a low rolling resistance.
The wide tires for mountain bikes are properly equipped with many plies to make them strong enough.
Besides sufficient strength of the carcass must it also be resistant against penetration by sharp objects.
For this, the carcass is, in anti-leak tires provided with an extra fiber layer of aramid fibers or a special hard rubber layer under the tread.
This strengthening of the carcass does provide a higher rolling resistance.
The carcass is provided with a rubber tread.
This ensures that the bicycle tire has grip.
As a material, both synthetic rubber is used as the natural rubber.
Natural rubber has the advantage that it has a lower rolling resistance, and that it has a somewhat higher resistance against punctures.
Synthetic rubber is more durable.
Besides a good grip, the tread must also protect the tire from sharp objects.
To properly protect the tape, use a strong and elastic rubber which is easy to bulges sharp objects without cracking.
The thicker the tread, the better the protection against punctures and the longer the life span.
However, this is at the expense of rolling resistance, which is also higher at a thick tread.
On the side, the tire can be fitted with a special ribbed tread for the dynamo and reflective lines (d) . Fit preferably tires with side reflection (reflective lines is legally required on a bicycle). Tires without special tread a dynamo may not be used.
For the inner tube, are natural rubber (latex) and synthetic rubber (butalex) used.
The latex tubes have lower rolling resistance and are more resistant to punctures.
The disadvantage of latex, is that it is less air dense than butalex inner tubes, and that it is more expensive.