OPINION OF THE COURT
A. LEON HIGGINBOTHAM, Jr., Circuit Judge.This is an appeal from the district court’s ruling on appellees’ motion for judgment notwithstanding the verdict pursuant to Fed.R.Civ.P. 50 and, alternatively, appel-lees’ motion for a new trial pursuant to Fed.R.Civ.P. 59. Finding that appellants had not established causation as their claims required, the district court granted appellees’ motion for judgment notwithstanding the verdict and, alternatively, ap-pellees’ motion for a new trial. Because we find that appellants did not meet their evidentiary burdens at trial, we will affirm the order of the district court.
I.
In late 1981 or early 1982, appellant Howard Overpeck (“Overpeck”), a professional truck driver, acquired a Powerman 990 pneumatic tire changer that appellees, Chicago Pneumatic Tool Company and Coats Company, had manufactured and marketed in 1964. Overpeck purchased the Power-man 990 from Gerald Tittle, a junk and *753used car parts dealer, for $100 and later installed it in the garage at his residence. At the time of purchase, Overpeck requested neither an owner’s manual nor a set of operator’s instructions.
On August 8, 1982, while using his Pow-erman 990 in his garage, Overpeck attempted to mount a new tire onto a wheel rim from which he had earlier successfully demounted another tire. Following what might be described as the standard procedure for mounting tires,1 Overpeck put the mounting tool through a 270-degree rotation which did not completely mount the new tire onto the rim. Overpeck then released the tire changer’s pedal so that the mounting tool could return to its starting position and be put through another rotation that would completely mount the tire. After Overpeck released the pedal, the mounting tool became disengaged from both the machine and tire and struck Over-peck in the left eye. As a result, Overpeck sustained injuries that substantially restrict and diminish his vision and that may result in further deterioration or even complete loss of his eyesight in the future.
Appellants brought a products liability action against appellees in the District Court for the Eastern District of Pennsylvania, claiming (1) that Overpeck’s Power-man 990 was defectively designed and (2) that it lacked adequate warnings concerning its hidden dangers. After jury trial, in accordance with the jury’s responses to interrogatories, the district court entered a judgment for appellees on the design defect claim and a judgment for appellants on the claim for failure to warn in the amount of $200,000.00. Appellees then moved for a judgment notwithstanding the verdict pursuant to Fed.R.Civ.P. 50 and, alternatively, for a new trial pursuant to Fed.R. Civ.P. 59. On March 25, 1986, the district court, finding that appellants’ evidence could lead to but one conclusion, entered a memorandum and order granting appellees’ motion for judgment notwithstanding the verdict. Overpeck v. Chicago Pneumatic Tool Co., 634 F.Supp. 638, 640-41 (E.D.Pa.1986). In the same memorandum and order, the district court, finding further that the jury’s responses to the failure to warn claim interrogatories were against the weight of the evidence, and that appellants’ counsel had at trial made prejudicial reference to a jury verdict in another case, also ruled alternatively that appellees were entitled to a new trial even if they were not entitled to judgment notwithstanding the verdict. Id. at 641. This appeal followed.
II.
In this appeal, we review a grant of a motion for judgment notwithstanding the verdict. Our inquiry therefore is whether there is sufficient evidence in the record to sustain the jury’s verdict. Acosta v. Honda Motor Co., Ltd., 717 F.2d 828 (3d Cir.1983). As this is a diversity case, we will apply the law of the appropriate state, which the parties acknowledge is Pennsylvania. See Erie R.R. Co. v. Tompkins, 304 U.S. 64, 58 S.Ct. 817, 82 L.Ed. 1188 (1938).
A.
Pennsylvania courts have adopted section 402A of the Restatement (Second) of Torts, which imposes strict liability on the *754seller of any product in a defective condition unreasonably dangerous to the user or consumer. See, e.g., Incollingo v. Ewing, 444 Pa. 263, 282 A.2d 206 (1971). Under section 402A, a product may be found to be defective and unreasonably dangerous if its manufacturer fails to warn the user or consumer of latent dangers in the product’s use or operation. Sherk v. Daisy-Heddon, A Division of Victor Comptometer Corp., 498 Pa. 594, 450 A.2d 615 (1982). A mere failure to warn of latent product dangers may therefore serve as the basis for recovery under section 402A. It should be noted, however, that in a case alleging the defendant’s failure to warn of latent dangers, Pennsylvania law also requires the plaintiff to “establish that the failure to warn adequately of dangers was the cause-in-fact and proximate cause of his or her injuries.” Conti v. Ford Motor Co., 743 F.2d 195, 197 (3d Cir.1984). This requirement demands that plaintiff prove more than that a defective product was involved in an accident; plaintiff must show that defendant produced a defective product and that product’s defect resulted in plaintiff's injuries. See Sherk, 498 Pa. at 598, 450 A.2d at 619.
Here, the district court’s grant of judgment notwithstanding the verdict was proper because appellants clearly failed to sustain the aforementioned burden. Appellants’ initial claim that the Powerman 990 was defectively designed was squarely rejected by the jury. App. at 35-36. Appellants’ temaining claim, that the Powerman 990 was defective because it lacked an adequate warning, was unsupported by their proof.
By their expert witness, James Currie, appellants specifically asserted that:
The other part of my claim for defective design is that, indeed, this is a machine with a fairly sophisticated, fairly high number of internal components that have to do with pneumatics and cables and pulleys and springs and return springs and air pressure. All of which has to perform a series of coordinated motions of the parts of the tools, such as the bead breakers and the rotation of the center post.
And, as a result of all that and the possibility of one or many — one or more of these features coming out of adjustment, either through leakage or evaporation or breakage or stretching or any number of other things, this machine can over time come out of adjustment and contribute to an uneven, jerky kind of rotation or movement of that tool, which would then contribute to its possibly becoming ungripped from the bead and the center post and tire.
And, as a result, I feel that one of the features that this machine lacks is a strong indication right on the machine that this machine does require periodic attention to those kinds of things. And, a warning to the effect that if the machine gets out of adjustment, that it can be a hazardous situation to continue to operate it.
App. at 15-16. Appellants thus asserted that the Powerman 990 should have warned that an uneven, jerky tool motion due to the tire changer’s misadjustment created the possibility that the tool would work itself free from the rest of the machine and injure a user. To prevail, appellants were required to show that the Pow-erman 990 was defective for its failure to warn and that that defect was the cause of Overpeck’s injuries. Appellants thus needed to show that Overpeck’s injuries resulted from use during uneven, jerky motion, which use a warning would have averted. Appellants, however, offered no evidence that the mounting tool flew off at a time when the mounting tool was moving in an uneven or jerky manner. When questioned concerning the machine’s operation at the time of the accident, Overpeck’s brother, Arlington, repeatedly stated that he could not describe the tool’s movement at the time of the accident because the events leading to injury occurred so quickly. App. at 89b, 92b-93b. Overpeck's brother, Glenn, directly stated that he could not describe the tool’s movement at the time of the accident. Id. at 97b-99b. Neither witness suggested that the tool’s movement at the time of the accident could be character*755ized as uneven or jerky. Indeed, Glenn Overpeck’s testimony indicates that the tool moved “about three-quarters” of its 360-degree revolution and stopped without difficulty as it was designed to do. See App. at 96b. This account of the bar’s proper 270-degree movement was corroborated by Overpeck himself, see App. at 68b, who never suggested that the mounting tool operated in an uneven or jerky manner at the time of the accident. Appellants thus plainly failed to put forth evidence that the type of accident that the allegedly required warning might have prevented— an accident resulting from the mounting tool’s uneven or jerky motion — actually occurred. Consequently, appellants necessarily failed to show that such an accident caused Overpeck’s injuries and cannot prevail on their failure to warn claim.
Even if we were to infer that Overpeck’s mounting tool was operating in an uneven or jerky manner at the time of the incident, we nevertheless would be required to find that appellants failed to produce sufficient evidence to defeat the motion for judgment notwithstanding the verdict. As noted above, at trial appellants bore the burden of establishing that the product’s alleged defect proximately caused the injury. In Pennsylvania, this burden requires plaintiff to demonstrate that an adequate warning would have modified his or her behavior so as to avoid injury. Powell v. J.T. Posey Co., 766 F.2d 131, 133 (1985) (interpreting Pennsylvania law). Here, appellants made no such showing. In fact, Overpeck’s own trial testimony clearly establishes that he was aware that the mounting tool might fly off during operation of the machine, whether or not the tool was operating in an uneven or jerky manner:
Q: [by counsel for appellees]: Before you depress that pedal and make the tool turn, what is holding the tooling in place?
A: [by Overpeck]: Your hand.
Q: Suppose you let go with your hand?
A: You don’t let go. You don’t let go with your hand.
Q: All right. What was holding the tool in place then [after the tool completed its 270-degree rotation]?
A: My hand. I still had my hand on the tool. I didn’t take my hand off the tool when I was operating the machine.
Q: Now, were you tugging on the tool at all while you’re doing this [operating the machine] or just applying pressure straight down?
A: To — I had my hand on there to make sure it didn’t fly up.
Trial Transcript, April 19, 1985, at 48-50. A warning that advised Overpeck of the possibility of the mounting tool’s flying off during uneven or jerky operation would have provided him with no new information and thus would not logically have affected his behavior. The conclusion that a warning would not have affected Overpeck’s actions is further supported by other testimony by Overpeck. Overpeck’s statement that “I had my hand on there to make sure it [the mounting tool] didn’t fly up,” id. at 50, indicates that appellant not only knew of the tool’s allegedly dangerous propensities but also believed he had a means for dealing with them. As we acknowledged above, a warning that advises of a danger that is known to a user is unlikely to affect his or her actions. A warning that advises of a danger that a user appreciates and has attempted to minimize is even more unlikely to affect that user’s actions since the user has already determined his or her course of action.2 Given the absence of *756any direct evidence offered by appellants to support a finding that a warning would have changed Overpeck’s behavior, and given the reasonable inferences to be drawn from Overpeck’s testimony, we cannot conclude that sufficient evidence existed to support a jury finding for appellants on the issue of causation.3
The dissent argues that appellants are, under the circumstances of this case, entitled to a presumption that carries their burden of establishing proximate causation.4 Even if we assume, as does the dissent, that appellants initially benefited from a presumption that an adequate warning would have affected Overpeck’s actions, we cannot conclude that appellants met their burden of demonstrating that such a warning would have averted an accident. Under Pennsylvania law, a re-buttable presumption5 “serves as a challenge for proof and indicates the party from which such proof must be forthcoming. When the opponent of the presumption has met the burden of production thus imposed, however, the office of the presumption has been performed; the presumption is of no further effect and drops from the case.” Commonwealth v. Vogel, 440 Pa. 1, 17 (1970) (quoted in Philadelphia to use of DePaul v. Philadelphia Auth. for Indus. Dev., 230 Pa.Super. 226, 230-31 (1974)). Overpeck’s testimony that he operated the machine with his hand on the mounting tool despite his awareness of its propensity to fly off certainly rebuts a presumption that a warning of the tool’s propensities would have caused him to act differently. Once the presumption working in appellants’ favor was rebutted by such evidence, it fell completely from the case. All that remained thereafter, then, was testimony offered by Overpeck concerning his awareness of the relevant danger. Appellants offered no evidence that a warning would have modified Overpeck’s behavior, not even a testimonial statement to that effect. Given the dearth of evidence to support a finding that a warning would have changed Overpeck’s behavior, the burden of production that shifted back to appellants after the possible comment j presumption was rebutted, and appellants’ burden of persuasion on the issue of causation, which never shifted, appellants cannot be said to have presented evidence sufficient6 to defeat a motion for summary judgment.7
*757IV.
For the reasons set for forth above, we will affirm the judgment of the district court.
. This mounting procedure may be described briefly. A user of the Powerman 990 first depresses the machine's foot pedal, resulting in the introduction of air into a chamber inside the machine. The pressure created by the introduction of air into the chamber forces fluid into a rubber "bladder" that expands and causes the working parts of the machine to rotate. For purposes of this appeal, the most important working part that is moved is the mounting tool, the component which allegedly injured Over-peck. One end of the mounting tool, which is essentially a bar, fits between the beads and rim of a tire that is to be mounted or demounted. The other end of the mounting tool is pressed against another working part, the center post key, which rotates the tool by turning. It is by rotation of the mounting tool when wedged between the tire and rim that a tire is mounted and demounted.
For mounting, the Powerman 990 is designed to initially rotate the mounting tool only 270 degrees. After the initial rotation, the mounting tool is returned to its starting position by release of the foot pedal which causes an exhaust of air from the inner chamber and allows springs within the machine to force the tool backward. After the mounting tool has been returned to its initial position, it may be rotated again to complete the mounting.
. Although the district court did not consider the defense, we note that Overpeck’s testimony concerning his appreciation of the risk presented by the mounting tool and his decision to operate the Powerman 990 in a manner that he believed would minimize that risk suggests an assumption of risk rather than a failure to warn proximately and actually caused the injuries here. We note also that assumption of risk may be a defense to a strict products liability action brought pursuant to section 402A if the injured party knew of the danger posed by a defect and voluntarily proceeded to use the product. See *756Ferraro v. Ford Motor Co., 423 Pa. 324, 223 A.2d 746 (1966).
. A contention that an adequate warning might have averted the accident by reminding appellant of the danger is unpersuasive. First, Over-peck’s testimony indicates that he was aware of the danger before and at the time of the accident. A reminder of the danger, therefore, would not have altered his behavior if Over-peck's testimony is to be believed. Further, appellants never claimed that Overpeck's Power-man 990 was defective because it lacked a warning that would have jogged his memory. Finally and most significant, under Pennsylvania law, where, as here, an inference that a warning would have reminded a user of a known danger is unsupported by independent evidence, such an inference is impermissible as mere jury speculation. See Conti v. Ford Motor Co., 743 F.2d 195, 198-99 (3d Cir.1984) (interpreting Pennsylvania law).
. The dissent bases its argument on the interpretation given the Restatement (Second) of Torts § 402A, comment j (1965) by the court in Technical Chemical Co. v. Jacobs, 480 S.W.2d 602 (Tex.1972). The Technical Chemical court concluded that where a product lacks an adequate warning, as is alleged here, a plaintiff benefits from a presumption that he or she would have heeded the warning. Id. at 606.
It is important to note that the comment j presumption suggested by the dissent could not help to satisfy appellants’ burden of establishing that the danger of which they contend Overpeck should have been warned in fact caused his injury. As noted previously, appellants also failed to meet this burden. It is also important to note that the dissent offers no explanation as to why Pennsylvania courts would adopt the Texas court’s interpretation of comment j to section 402A.
. The dissent does not contend that the comment j presumption is conclusive.
. The dissent suggests that the jury could have reasonably inferred that a warning would have changed Overpeck's actions from his extensive prior operation of the tire changers, which, the dissent suggests, indicated his ability to read and follow warnings. Although we do not consider the reasonableness of such an inference in other contexts, we do note that such an inference would here be unreasonable due to the existence of substantial specific testimony, some provided by Overpeck himself, that Overpeck was aware of the danger of which the warning would have advised and that he had determined *757how to confront and minimize that danger. To here permit the inference suggested by the dissent would be to allow juries to negate the probative force of specific direct evidence with purely speculative inferences.
We also find somewhat problematic the dissent’s assertion that a pause or jerk might have caused an uneven motion that caused the mounting tool to fly off, given the extensive testimony that the incident and the events leading up to it occurred too quickly to describe. A pause immediately preceding the tool's flying off would seem an anomolous element of a chain of events that occurred too quickly to describe. Either a pause or a jerk that immediately preceded the tool’s flying off would seem an observable, memorable occurrence about which at least one of three witnesses would testify. In short, the dissent argues that appellants were entitled to judgment on an inferential theory that appears to be substantially contradicted by existing testimony.
. See note 7 on page 757.
*7577. Since we conclude that the district court properly granted appellees' motion for judgment notwithstanding the verdict, we will not consider the district court’s conditional grant of a new trial. That grant is mooted by our initial ruling on the grant of the motion for judgment notwithstanding the verdict. 5A J. Moore, W. Tag-gart & 1. Wicker, Moore’s Federal Practice. 50.14 (2d ed. 1986); Mitchell v. District of Columbia, 347 F.2d 484 (D.C.Cir.1965).