The magnetization switching of micron-scale thin film Co rhombic rings is studied by magnetic force microscopy and electrical measurements. The rhombic rings have a 1.4 mu m/0.7 mu m major/minor diameter with 200 nm width. A magnetic field ranged from 130 Oe to 200 Oe causes motion of domain walls (DWs) around the ring in a direction controlled by the magnetic field orientation. In addition to the well-known 'onion' and 'vortex' states, intermediate states such as horseshoe and hard-axis onion states were formed for certain field cycles, in agreement with micromagnetic simulations and anisotropic magnetoresistance calculations. DWs induce a 0.4% resistance change when the external magnetic field is cycled. (C) 2015 Elsevier B.V. All rights reserved.