A compacting unit for compacting a fiber composite supplied by a drafting unit of a spinning machine has a beam on which at least one suction drum equipped with a suction zone is rotatably mounted on an axle. A clamping roller mounted on the beam is in contact with the suction drum to form a clamping line at the end of the suction zone under the action of a pressure element mounted on the beam. The clamping roller is mounted so it is rotationally movable on a pressure arm that is equipped with a spring element and is mounted on the beam so it can pivot over a pivot axis.