Timepiece with rigid casing and casing method

A timepiece comprising a middle, a detachable back mounted on the middle, a movement and casing elements for rigidly holding the movement in an inner volume of the middle, wherein the casing elements comprise:

• a first casing circle pressing against a shoulder formed in the middle;
• a second casing circle, said movement being rigidly held between the first casing circle and the second casing element via a peripheral rib of the horology movement, the first casing circle and the second casing circle being superimposed with no direct contact with each other;
• a clamping element, separate from the detachable back, in direct contact with the second casing circle, the clamping element being designed to compress the movement axially between the first casing circle and the second casing circle and to compress the first casing circle axially against the shoulder of the middle.