While defendants do not concede their negligence and plaintiff does not concede his contributory negligence, the only question plaintiff argues in this Court is whether the trial judge erred in finding that the issue of last clear chance does not arise on the undisputed facts in this case.
*81  The doctrine of last clear chance presupposes negligence and contributory negligence. Arvin v. McClintock, 253 N.C. 679, 118 S.E. 2d 129. It is applicable when both plaintiff and defendant have been negligent and the defendant has time, after the respective negligences have created the hazards, to avoid the injury. 6 Strong, N.C. Index 2d, Negligence, § 12.
 We think it clear that in standing on the two-inch blade of the motor grader plaintiff voluntarily placed himself in a position of imminent danger. This constituted contributory negligence as a matter of law. Huffman v. Huffman, 271 N.C. 465, 156 S.E. 2d 684; Burgess v. Mattox, 260 N.C. 305, 132 S.E. 2d 577; Tallent v. Talbert, 249 N.C. 149, 105 S.E. 2d 426.
 Whether there is evidence to support a finding that defendants had the last clear chance to avoid injury to plaintiff and negligently failed to avail themselves of this opportunity presents a closer question. However, we find the facts in this case indistinguishable from those considered by the Supreme Court in the case of Presnell v. Payne, 272 N.C. 11, 157 S.E. 2d 601, and affirm the judgment on the basis of the majority opinion in that case. In Presnell one of the defendants attempted to start a station wagon by pushing it with a truck. Plaintiff’s intestate took a seat on the right front fender of the truck for the purpose of preventing damage to the station wagon by the front bumper of the truck overriding the rear bumper of the station wagon. The station wagon started and moved forward as defendant applied brakes for the purpose of stopping or slowing down the truck. Plaintiff’s intestate lost his balance, fell from the fender, and was fatally injured. The dissenting opinion interpreted the evidence as showing that defendant first put on brakes abruptly, thereby causing plaintiff’s intestate to fall forward from the fender of the truck, and thereafter eased or released his brakes to such extent that the truck struck plaintiff’s intestate after he had fallen. The Supreme Court, with two justices dissenting, held that the trial court correctly refused to submit the issue of last clear chance because evidence to support the issue was lacking.
Plaintiff contends that the cases are distinguishable in that in Presnell plaintiff’s intestate should have anticipated that defendant would stop the truck as soon as the station wagon started; whereas, the plaintiff here had no reason to anticipate that the individual defendant would stop the motor grader *82before reaching the point of destination. We do not regard this distinction, if in fact it is a distinction, as sufficient to remove this case from the control of the precedent set in Presnell. Actually, although plaintiff contends that the motor grader “jerked,” and that this caused him to fall, his testimony clearly indicates that the “jerk” was nothing more than a slowing of the machine by no more than three or four miles an hour, and then an acceleration back to its original speed. Moreover, plaintiff knew the machine was subject to “jerk” because he had seen it do so in the past. When plaintiff got on the narrow blade, he assumed all of the natural risks incident to riding in such a dangerous position, including the risk that the machine would not be operated at a constant speed at all times and the risk that it might “jerk” as he had observed it do on other occasions.
Under the authority of Presnell v. Payne, supra, the judgment is affirmed.
Judges Campbell and Britt concur.