The divisions are determined by the speed a horse runs the cloverleaf pattern. The Divisions or D races are split using the designations: 1D, 2D, 3D, 4D, 5D and 6D. 1D class are run by the horses and riders with the fastest times. ... The fastest time is a 1D, then the 2D would be 5 seconds slower than the 1D time.