An anti-friction bearing interposable at the crossing-over point between two spokes of a bicycle wheel

An anti-friction bearing interposable at the crossing-over point between two spokes (5a, 5b) of a bicycle wheel comprises a body (6) having a through hole (7), with a completely closed continuous part (8), and giving out onto two opposite ends (9) of the body (6) to receive through it one of the two spokes. The body (6) further includes a portion of external surface (10) in contact with the other spoke.