Abstract: A timepiece escapement mechanism, including a balance having no roller and an escape wheel, between which impulses are transmitted by a flexible, single-piece mechanism, connected by at least one flexible strip to a fixed structure or to the wheel. Oscillation is maintained by a balance spring ending in a balance spring stud which is mobile during operation, and which is guided by a flexible guide member with flexible strips, and whose center of rotation is coaxial to the balance, the balance spring stud receiving a pin which is mobile in a cam path of the wheel. During the oscillations, the balance spring stud is moved relative to its locking position under action of force exerted by the balance spring, and the pin maintains and regulates the oscillation.