A timepiece resonator including an inertial element moveable in relation to a fixed structure, and suspended to a flexible guide including flexible strips crossed in projection on a plane XY at a single crossing zone ZC, each one deformable in a plane parallel to the plane XY each one extending in a ribbon on either side of a neutral surface perpendicular to the plane XY and joining the first recess with the structure and the second recess with the inertial element, and including at least one rib asymmetrical in relation to its neutral surface, and, at the crossing zone ZC, either each flexible strip does not include any rib, or each rib is asymmetrical in relation to its neutral surface.