The invention relates to a tensioning device of a strapping device for strapping packaged material with a strapping strip, in particular with a plastic strapping strip, said device being provided with a tensioning wheel which is operatively connected to or can be operatively connected to a drive device in order to rotate the tensioning wheel about a rotational axis, said tensioning wheel being provided with a circumferential surface which is designed to engage into the strapping strip. The tensioning device is to be improved such that disadvantages occurring due to the relative speed between the tensioning wheel and the strip during the strip retraction phase are prevented as much as possible. This is achieved in that at least one movable spacer is provided on the tensioning wheel in the region of the circumferential surface of the tensioning wheel, said spacer being arrangeable in a first position and in a second position different from the first position. In the first position, the spacer can be arranged at a first distance to the rotational axis of the tensioning wheel at least in some regions with respect to a circumferential direction of the tensioning unit and at a second distance to the rotational axis of the tensioning wheel at least in some sections in the second position. The first distance differs from the second distance, and the spacer projects beyond the circumferential surface of the tensioning wheel in at least one of the two positions.