A "clincher" is the most common type of rim used on bicycle wheels. Clincher wheels are similar to automobile rims in terms of how the tire adheres by means of a ridge on the inside of the rim that "clinches" a bead running along the inside of the tire.
HOW A CLINCHER WORKS
A clincher bicycle wheel "clinches" the tire by means of a ridge on the inside of the wheel rim. When the tire is properly mounted on the rim, beads (made from wire or other strong material) along the inside of the tire seal snugly against the ridges inside the rim. When the tire is mounted on the wheel rim and properly inflated, it holds firmly in place without shifting or moving.