Misguided doctors or marketing agents?


In the 1980′s, Bell, a helmet manufacturer, was keen to expand the market for bicycle helmets, its most profitable product. It approached the Snell foundation and offered funding for research on bicycle helmets. The Snell foundation chose avid helmet lobbyists to conduct this “research”.

The helmet lobbyists initial “research” claimed that helmets reduce the risk of head injuries by 85% and the risk of brain injuries by 88%. Both claims are physically impossible due to inherent bio-mechanical limitations of helmets. Despite being riddled with methodological errors, this research was widely embraced within the medical community, who was eager to believe the claims. 

The Snell foundation has kept funding these researchers, who have produced more “research” that made other implausible claims. This culminated in them publishing a biased review of their own flawed research in the Cochrane Review, a prestigious medical research database.

Helmet manufacturers have greatly benefited from this deceit, with the market for bicycle helmets strongly growing in the early 1990′s. Bicycle helmets became so profitable that helmets manufacturers could reinvest their profits into lobbying for helmet legislation, including sending executives all the way to Australia to push for a helmet law. With a piece of molded polystyrene selling for $200, the profits are huge. Helmet manufacturers are laughing all the way to the bank, while cycling has been tarnished as a dangerous activity requiring expensive equipment.

In June 2013, the US government dropped its claim that helmets reduce 85% of head injuries, following a petition under the Federal Data Quality Act. it initially made the claim based on the research mentioned above, but then admitted that there was no credible basis for this claim.


The infamous misleading “research”

The most widely quoted research on bicycle helmets is a study published in 1989 in the US, that makes the bold claim that:

“we found that riders with helmets had an 85 percent reduction in their risk of head injury … and an 88 percent reduction in their risk of brain injury”

How can helmets reduce 85% of head injuries considering they don’t cover the face where 70% of head injuries are?
How can helmets reduce 88% of brain injuries considering they cannot protect against the main cause of brain injury, rotational acceleration?


Injuries to the skull (the part of the body a helmet covers) constitute 10% of cycling injuries,
or 30% of what is usually classified as head injuries (including face injuries).

How did they arrive at such impossible claims?
They compared a helmeted group who rode supervised in parks with an un-helmeted group who rode unsupervised on busy roads, and then attributed all the difference in head injuries to helmets. They failed to consider confounding factors, a common error in statistics.

Some “studies” compare helmeted cyclists in bicycle paths with unhelmeted cyclists on roads. They attribute all the difference to helmets, ignoring the more dangerous road environment. This is an example of failing to consider confounding factors, a common mistake among helmet studies.

This flawed study was widely criticized. Flaws included failure to select a representative control group, a misuse of the odds-ratio (making the 85% claim invalid), a lack of serious injuries involving motor vehicles, and failure of adjust the results by age group. The study is so full of errors and limitations that very little can be concluded from it.

As summarised in this review:

“The study compares groups of cyclists who chose to wear helmets with those who did not. Many variables, such as the reasons for wearing a helmet and attitudes to risk, were not controlled for by the researchers and may have influenced the results.”

The 85% figure is meaningless. It does not correspond to physical protection provided by helmets, but to the authors own generous estimate misrepresented as the result of their “study”. Many researchers have tried to replicate its results, but have been unable to do so. Amid severe criticism over the implausible claim, the authors had to re-work their data, and arrived at a lower effectiveness rate.

The data from the study indicates that helmet wearers were 7 times more likely to have accidents. Using their methodology to calculate odds ratios, NOT wearing a helmet is associated with an 88% reduction in the risk of falling off your bike. This went unnoticed by the study authors, who asserted that helmets were effective as they appeared to reduce head injuries in case of accidents. They ignored that the risk of accidents increased significantly.

Instead of claiming
“Helmets protect x% of head injuries”
A more objective assessment would be:
“Helmets appear to protect against some head injuries. However, they are also associated with more accidents.  Overall, it is not clear whether there is a net safety benefit.”

A more accurate assessment, but unlikely to make headlines or satisfy the sponsors of the study

Despite being flawed, this study was influential. The research claims were widely embraced within the medical community, who was eager for a solution to the dreadful incidences of chronic disability from brain injury. Few questioned the methodology of the research, as they were eager to believe its claims. Despite the authors admitting errors, it is still widely quoted as if it was the truth. It reinforces a popular belief.

This research became a model for further “research” replicating its flaws and bias. Such research, based on small samples, tends to jump to a premeditated conclusion far too eagerly, with a disturbing lack of scientific discipline. Most studies exaggerate the protection provided by helmets while ignoring the increase in accidents. This one-sided view has deceived many people. Once something becomes accepted as the norm, the medical research field takes some time to correct its mistakes.

The sheer volume of “research” based on this flawed model helped convince many people in the medical community that “helmet save lives”. Doctors sometimes even claim that a bicycle helmet saved a cyclist. Yet they have no scientific basis for that claim, they don’t know what would have happened without a helmet.

The vested interests behind this “research”

How can a small team send a whole industry on a dead end, misleading so many people into believing that polystyrene-based helmets are the solution to cycling safety? Is this an accident, or is there a hidden vested interest? It was not an accident. The history of bicycle helmets indicates that commercial interests have been a key driver.

In 1956, a racing driver called Peter Snell died from head injuries sustained in an accident, despite wearing a Bell helmet. His death triggered calls to research helmets effectiveness, leading to the creation of the Snell foundation. Bell stopped production of the helmet that Peter Snell had been wearing and started focusing of the value of the Snell helmet standard, developing a close relationship with the Snell foundation.

In the 1970′s, Bell introduced polystyrene-based bicycle helmets. They became popular among some racing cyclists, but not mainstream cyclists. In the 1980′s, Bell started to market bicycle helmets more aggressively. They became the most profitable range of helmets. In the mid 1980′s, Bell suggested that the Snell foundation should commission research into bicycle helmets effectiveness, and provided funding to do so.

Snell chose 3 researchers to do the study, including Dr. Frederick Rivara. Dr. Rivara was known at the time as a bicycle helmet advocate and an active lobbyist for increased used of bicycle helmets. This was an odd choice. To ask an avid helmet lobbyist to conduct helmet research is a bit like asking a priest to research religion: there is little chance that the research will be objective. Additionally, Snell mentioned that the study was “done to demonstrate the effectiveness of bicycle helmets in reducing head injury”. Note the assumption of effectiveness upfront instead of asking an open-ended question. This is a similar bias as in this study. The bias seems to come from both Snell foundation and the selected researchers.

The study concluded that helmets protected against 85% of head injuries, defying the bio-mechanical limitations of helmets.

Using sponsored “research” to promote helmets and lobby for legislation

This sponsored  study bold claim was used by Bell in its advertising.

Bell advertising, using the “study” it sponsored to claim that helmets prevent 85% of head injuries

As with many helmet promotions, scaremongering is a key tactic. Parents are the easiest target, easily scared into buy a product to protect their child from an exaggerated danger. Parents became the prime target of the helmet industry. Such scaremongering has damaging side-effects, misrepresenting cycling as more dangerous than it really is and discouraging a healthy, economical and environmental friendly mode of transport.

This flawed research was used as the basis for lobbying government agencies to promote bicycle helmets, with Bell providing funding and support for lobbying. Lobbyists started to push for mandatory legislation. The commercial benefits of such legislation was clear to the helmet industry. Policy-makers (most of whom did not cycle) started to believe that helmets were the solution part of cycling safety.  Other helmet believers joined the lobbying, notably the Bicycle Helmet Safety Institute.

As most helmet manufacturers are from the US, the lobbying was initially focused in the US. Bell funded organisations like SafeKids that were promoting bicycle helmets and actively lobbying for mandatory helmet laws. Funding SafeKids was a clever move, as it made it look like there was popular demand for helmet legislation, while in fact it was a minority funded by the helmet industry. It is shrewd to hide commercial interests behind benevolent organisations who can sincerely appear to be acting in the best interest of the public. This lobbying resulted in mandatory helmet laws being imposed in various US jurisdictions over the last 25 years, mostly affecting children.

Helmet manufacturers also saw the benefits in lobbying outside the US. A vice-president from Bell helmets flew all the way to Australia to be present at EVERY hearing regarding passing a mandatory helmet law. These expensive executive overseas trips indicate the high value placed in lobbying for mandatory helmet laws.

Thanks to the lobbying efforts, the market for helmets expanded rapidly in the early 1990′s, almost doubling between 1993 and 1995. This lead to record profits for the bicycle helmet division of Bell, that was reportedly making more money than the rest of the company. In 1995, the bicycle helmet market was estimated to be worth $200 million dollars. Large profits could be re-invested into further lobbying and funding of “studies”.

Funding more flawed research

The Snell Foundation kept funding this team of researchers, who kept producing more “studies” promoting helmets. For example, this study, published in 1996, made this bold claim:

“Bicycle helmets, regardless of type, provide substantial protection against head injuries for cyclists of all ages involved in crashes, including crashes involving motor vehicles.”

This study attracted a lot of criticism. Besides the flaws, there is the lack of disclosing conflicts of interests:

“This research was supported by a grant from the Snell Memorial Foundation, to which the principal bicycle helmet manufacturers are contributors.”

The authors again made the error of failing to consider confounding factors. They made implausible claims, like the claim that there is no significant difference in protection between a soft-shell helmet (ie. a naked piece of polystyrene) and a hard-shell helmet (ie. a motorcycle helmet), or the claim that helmets are just as effective in high-speed accidents involving cars than they are in low-speed falls.

Close analysis of their data indicates that:

“The data show that, apparently, the protective effect of a helmet increases with increasing severity of injury. It is extremely difficult to accept such a result, and indeed, it is the opposite of what is seen in population level studies, which return the more sensible outcome of declining protection with increasing severity of injury. It must be the case that confounding factors systematically caused non-helmeted cyclists to be in more severe crashes”

To make such unqualified bold conclusions illustrates a poor understanding of the bio-mechanical limitations of helmets. These implausible results did not raise alarm bells in the study, nor did they cause the “researchers” to question their assumptions. Such a lack of scientific discipline is disturbing. The authors seemed far too eager to reach conclusions that fit their preconceptions instead of conducting rigorous scientific analysis. This is not science, this is propaganda disguised as science, funded by a biased party.

The implausible Cochrane review

In 1999, the same researchers published a “review” of helmet studies in the Cochrane review, that boldly claims

“helmet dramatically reduces the risk of head and facial injuries for bicyclists involved in a crash, even if it involves a motor vehicle”

The claims above again ignore the bio-mechanical limitations of helmets.  Polystyrene-based “helmets” are only designed for minor impacts and do not cover the face.  They are not only tested at speeds below 20 km/h.   In a high speed crash, they tend to disintegrate on impact, absorbing very little energy.

These claims are contradicted by a helmet testing expert, Brian Walker, of the helmet-testing lab Head Protection Evaluations

“Cycle helmets are designed for falls without any other vehicle involved …

The tests that cycle helmets currently go through mean that they should offer similar protection to a pedestrian who trips and falls to the ground …

In today’s road traffic accidents, it’s not unlikely for a cycle helmet to be subjected to severity loads greater than it is designed to cope with.”

These misleading claims were also rebutted by an independent researcher:

“It is concluded that the review takes no account of scientific knowledge of types and mechanisms of brain injury. It provides, at best, evidence that hard-shell helmets, now rarely used, protect the brain from injury consequent upon damage to the skull. The review therefore is not a reliable guide to the efficacy of helmets and to interventions concerning their use.”

This biased review attracted much criticism, including the following:

“The review is not independent. Four of the seven papers selected for inclusion were the work of the reviewers themselves and their data dominate the analysis …

Only case-control studies were considered for inclusion, although non-randomised studies of this type are acknowledged to be prone to bias because of the difficulty in controlling for the many independent variables …

The paradox presented by the failure of other types of studies (e.g. whole population and time-series data) to show any benefit from large increases in helmet use – let alone the substantial benefits predicted by the studies reviewed – is left unstated and unaccounted for

The authors are dismissive of the possibility of risk compensation. However, it has subsequently been demonstrated that child cyclists often ride more riskily and suffer more crashes when wearing a cycle helmet (Mok et al, 2004) and that adults are more likely to ride on busier roads if helmeted (Gregory, Inwood and Sexton, 2003).

Similarly no consideration is given to rotational injuries, which dominate the most serious injuries. Helmets have not been shown to mitigate rotational brain injury and there is evidence they may increase the risk and/or severity of rotational injury.(BHRF, 1039).

Claims are accepted of efficacy for which no plausible mechanism exists (e.g. the prevention of mid-face injuries), where the reviewed data set is too small to make reliable inference (e.g. the result of collisions with motor vehicles), and which would not be possible even if helmets prevented all head injuries (e.g. an increase of 35% in cyclists wearing helmets leading to 66% fewer head injuries).

There is misleading interpretation of ‘odds ratio’, which is used interchangeably in the review with ‘percentage reduction in head injuries’. This exaggerates the predicted benefit of helmets and masks the fact that studies of this type are not truly predictive, being essentially the authors’ estimate of what proportion of the observed differences between two groups can be assigned to a single factor. Furthermore, the reviewed paper showing the least benefit from helmets is omitted from computation of odds ratio, thus again exaggerating benefit.”

This “review” ignores contradictory studies, an indication of publication bias (the tendency to only include material supporting a predetermined conclusion).  One of the study included in the review reported a higher accident rate and higher neck injuries for helmeted cyclists.  That was ignored in the summary.

This review also claimed that cyclists would need to increase their risk-taking four-fold to overcome the protection of helmets, another invalid claim refuted by an independent researcher.

The same researchers then took advantage of prestige from the Cochrane review to peddle their beliefs further, for example in this article titled “Bicycle helmets: it’s time to use them” makes this bold claim:

“The evidence that they reduce head injuries is too strong to ignore.”

The article concludes with this unsubstantiated claim:

“Further delays in promoting the use of helmets will be measured in the number of lives ruined by the devastating consequences of preventable brain injury.”

Their conviction is strong, like their lobbying efforts.  However well-meaning their intent is, misrepresenting the truth can have unintended consequences, like increasing the risk of accidents, leading to results opposite of the good intentions.  Unfortunately, zealots tends to be blind of the negative consequences of their dogma.

This biased Cochrane review is frequently quoted by helmet zealots as vindicating their beliefs.


What is fascinating about this “research” is how it contradicts the fundamental limitations of polystyrene-based helmets, while ignoring real-world data from whole-population studies, where a large rise in helmet wearing did not show any benefit.  Yet despite being biased and flawed, this “research” has been highly influential.

This has been a remarkable achievement, manufacturing an artificial perception that has helped generate large profits for the helmet industry.  With a piece of molded polystyrene selling for $200, the profits are huge.  No wonder Bell helmets still spends so much money on sponsoring racing cyclists.  Let the profits roll.

 Bell advertising in the Tour de France 2011

Update July 2013

In June 2013, the US government dropped its claim that helmets reduce 85% of head injuries, following a petition under the Federal Data Quality Act. It initially made the claim based on the 1989 research mentioned above, but then admitted that there was no credible basis for this claim.

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3 Responses to “Misguided doctors or marketing agents?”

  1. Chris says:

    How is it possible that other researchers interested in the field did not publish contradicting studies immediately? Or the lobby was so strong that no one stood up?

    • admin says:

      Many independent researchers stood up against this flawed “research”, especially after being unable to replicate its 85% claim. This page provides a summary of several contradicting studies published:

      In the end, the US government dropped the claim the helmets protect again 85% of head injuries, as they had to admit that this claim had no foundation:

      The bicycle helmet lobby is not that strong. But it deceived a lot of people for more than 20 years, enabling helmet manufacturers to reap huge profits.

  2. Jody McAllister says:

    Why are bicycle helmet lobbyists allowed to misrepresent their biased beliefs as “research” without having to disclose their vested interest?

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