Restraining device for securing a user in a ride, comprising - a belt retractor mechanism which can be fixed to a vehicle element, - at least one guide element, which can be fixed to the vehicle element in such a way that the guide element is movable between a securing position, in which the user can be fixed to the vehicle element, and a release position, in which the fixing of the user to the vehicle element is cancelled, - a belt system (3a, 3b, 3c) comprising at least a first belt, - wherein the first belt is a lap belt with two-point securing which, in the securing position, can be positioned around the pelvic area of the user and at least one end is fixed to the belt retractor mechanism, - wherein the belt retractor mechanism has at least one belt retractor unit (7a-7d) for adapting a length of the first belt by means of unwinding and winding up the first belt - and a locking unit for preventing the first belt from unwinding in the securing position, - wherein the first belt can be positioned in the securing position by the guide element in such a way that the user is secured to the vehicle element by means of the first belt - and wherein the locking unit is configured in such a way that, in the securing position, it cannot be released by the user and releases the fixing of the user only by releasing the locking effected by the locking unit and moving the guide element from the securing element into the release position, - wherein the restraining device comprises a control device which, to adapt the length of the at least one first belt, controls the belt retractor unit in such a way that the latter is changed from a blocking position, in which no length adaptation is possible, to an unlocked position, in which length adaptation is possible, - wherein the blocking position corresponds to the securing position during ride operation and the unlocked position corresponds to the release position. - a belt retractor mechanism which can be fixed to a vehicle element, - at least one guide element, which can be fixed to the vehicle element in such a way that the guide element is movable between a securing position, in which the user can be fixed to the vehicle element, and a release position, in which the fixing of the user to the vehicle element is cancelled, - a belt system (3a, 3b, 3c) comprising at least a first belt, - wherein the first belt is a lap belt with two-point securing which, in the securing position, can be positioned around the pelvic area of the user and at least one end is fixed to the belt retractor mechanism, - wherein the belt retractor mechanism has at least one belt retractor unit (7a-7d) for adapting a length of the first belt by means of unwinding and winding up the first belt - and a locking unit for preventing the first belt from unwinding in the securing position, - wherein the first belt can be positioned in the securing position by the guide element in such a way that the user is secured to the vehicle element by means of the first belt - and wherein the locking unit is configured in such a way that, in the securing position, it cannot be released by the user and releases the fixing of the user only by releasing the locking effected by the locking unit and moving the guide element from the securing element into the release position, - wherein the restraining device comprises a control device which, to adapt the length of the at least one first belt, controls the belt retractor unit in such a way that the latter is changed from a blocking position, in which no length adaptation is possible, to an unlocked position, in which length adaptation is possible, - wherein the blocking position corresponds to the securing position during ride operation and the unlocked position corresponds to the release position.