A rotor (10) for use in a centrifuge includes a rotor body (12), a drive hub (20), and a balance ring (16, 160). The rotor body (12) includes an elongated bore (32) extending along its axis of rotation (24), and an upper surface (26) having an annular groove (42). The drive hub (20) is mounted within the elongated bore (32), and includes a drive portion (138) having a cross-sectional shape that is complementary to the cross-sectional shape of the elongated bore (32). The drive hub (20) applies torque to the rotor body (12) via engagement of the drive portion (138) with the lower bore opening (36) of the rotor body (12). The balance ring (16, 160) is positioned in the annular groove (42), and includes a plurality of apertures (78, 163) formed in an upper surface (90, 170) thereof. Each of the apertures (78, 163) is configured to receive a weight (80, 164) so that the rotor (10) can be balanced by selectively adding weights (80, 164) to one or more of the apertures (78, 163).