Bicycle tires come in two main types: clincher and tubular. Clincher tires make up 99 percent of all tires used on modern road and mountain bikes, says famed bicycle mechanic and writer Sheldon Brown. Clincher tires have an outer shell made of fabric and rubber that protects a more pliable inflatable inner tube on the inside.
Bead
The bead of a clincher tire refers to the two metal hoops that act as the spine of the tire. The beads are traditionally made from woven steel cable that holds the circular diameter of the tire while still being pliable. The bead sits in the inner grooves of the rim to hold the tire in place. When the tire inner tube fully inflated, the beads seat firmly in these grooves and cannot be removed without special tools.
Fabric
The main part of a clincher tire is the fabric woven between the two beads. The fabric is often nylon cord because of its strength and durability, but other materials such as Kevlar are sometimes used for improved strength. Manufacturers use threads of thick or thin diameters, potentially giving tires of similar durability a different threads per inch count. The fabric is woven diagonally between the beads in layers to give the tire a strongly supported shape.
Rubber
A layer of rubber is laid on top of the fabric to complete the clincher tire. This rubber is mainly in place to prevent damage to the fabric and absorb punctures that could flatten the inner tube. Hard rubber wears down less, but offers less traction than a soft rubber compound. Road bicycle tires often have a smoother surface of rubber to limit rolling resistance and improve speed. Mountain bike clincher tires have rubber formed in high tread knobs for better traction.
Tubular Comparison
Tubular tires are sometimes called sew-ups because they do not have beads and the two ends of the tire are sewn together with the inner tube inside. Clincher tires that perform as well as tubular tires are significantly cheaper, according to Brown. But tubular tires are lighter and less prone to pinch flats than clinchers. Clincher tires take more time to change than tubular tires, but because you can remove the inner tube, you can often patch flats rather than replacing the entire tire.
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