Bearing, particularly a shock absorber, and rotary wheel set of a timepiece movement

A bearing, particularly a shock absorber, for an arbor or staff (16) of a rotary wheel set of a timepiece movement, for example a balance staff, the bearing (18, 20) comprising a bearing block (13) provided with a housing (14) and an endstone (22) arranged inside the housing (14), the endstone (22) comprising a main body provided with a cavity configured to receive a pivot (17, 20) of the arbor (16) of the rotary wheel set, the pivot (17, 30) having the shape of a first cone (26) having a first solid angle (31, 36), the apex (29) of the first cone being rounded with a predefined first radius of curvature comprised in a range from 0.2 μm to 50 μm, the cavity having the shape of a second cone (28) having a second solid angle (32) greater than the first solid angle (31, 36), such that the pivot (17, 30) can rotate in the cavity, the apex of the second cone (28) being rounded and having a predefined second radius of curvature, characterized in that the second radius of curvature is smaller than the first radius of curvature.