Locking and unlocking device for a sports boot

A locking and unlocking device for forming an interface between a shell base and an upper cuff of a sports boot, wherein the upper cuff is articulated in rotation around the shell base, the locking and unlocking device comprising:

• an actuation element;
• a lock;
• and
• a rear deflector,
• wherein the actuation element is mobile between a first position and a second position, controlling the position of the lock and the position of the rear deflector such that:
• in the first position of the actuation element, the lock occupies a locking position in which the lock can block the upper cuff in rotation relative to the shell base, and the rear deflector occupies a low position in which it can close a cut-out at the rear of a shell base;
• in the second position of the element, the lock occupies an unlocking position in which the lock can release the rotation of the upper cuff relative to the shell base, and the rear deflector occupies a high position in which the rear deflector can open up at least partly a cut-out at the rear of the shell base, in order to increase the amplitude of flexure of a lower leg in the sports boot.