A method of manufacturing an electric-motor rotor may include providing a magnet of sintered magnetic material, the magnet having a first diameter; providing a sheath of composite material, the sheath having an inner diameter smaller than the first diameter; reducing the first diameter to a second diameter; fitting the sheath onto the magnet when the magnet has the second diameter; and letting the magnet with the sheath fitted thereon to interfere, allowing the sheath to exert inward pressure on the magnet. An electric-motor rotor may include a magnet of sintered magnetic material, the magnet having a first diameter; and a sheath of composite material, the sheath having an inner diameter smaller than the first diameter. The sheath may be associated with the magnet in such a way that the magnet with the sheath fitted thereon interfere so that the sheath exerts inward pressure on the magnet.