1 Don't pull straight back on the reins, it can encourage a horse to back up while bucking. 2  Pull one rein to the side. 3  Preforming a one rein stop will also help to stop a bucking horse. 4  Grab one rein closer to the bit and draw it back to your thigh. 5  Make sure you do not also pull on the other rein. Don't pull straight back on the reins, it can encourage a horse to back up while bucking. 2  Pull one rein to the side. 3  Preforming a one rein stop will also help to stop a bucking horse. 4  Grab one rein closer to the bit and draw it back to your thigh. 5  Make sure you do not also pull on the other rein.