CRAG

Most sport cyclists wear their helmets as it is “obvious” that they protect them.  But do they really?

Since helmets have been made mandatory for racing cyclists, deaths of professional cyclists while racing have doubled.  So where is the protection provided by helmets?

It is odd that helmets  are imposed on racing cyclists as they travel at speeds far greater than what these polystyrene helmets are designed to handle.

Helmets have brought a new stream of sponsorship income for professional cycling.  Who has it benefited besides helmets manufacturers?

This  result of increased deaths after widespread helmet use is consistent with what was observed after the helmet law in Australia, where a 50% increase in accidents, death & serious injuries was reported for child cyclists in NSW.

Do helmets provide sufficient protection to compensate for the increased risk of accidents?  The evidence so far is that they don’t.

Politicians claim that “Helmets save lives”.

Is this true?  CRAG has asked for evidence, but the Australian government has been unable to provide convincing evidence.  This is not surprising, as there is actually contrary evidence, showing that the risk of death and serious injury increased by 50% for child cyclists in NSW after the helmet law.

Bicycle helmets increase risks in several ways:

1.  Increased risk of having an accident, through risk compensation.  Risk compensation is a well-known safety phenomenon that has been confirmed for children and for cyclists in this research that reports that helmeted cyclists tend to compensate by riding faster.  Helmets seem to affect motorist behavior as well, with research showing that motorists drive closer to helmeted riders and are more likely to hit them.  After the helmet law, the risk of non-head injuries increased by 50% for child cyclists in NSW, indicating a significant increase in the risk of accidents.

2.  In the event of an accident, increased risk of the head hitting the road.  Helmets increase the volume/size of contact area of the head.  This study reports that helmeted riders are more than twice as likely to hit their head in an accident, with the additional impacts being to the sides.  This is consistent with post-crash studies that found that most helmets show impacts to the side, areas where a bare head may not have been hit.  A 1988 study found that helmeted riders report hitting their heads seven times more often than un-helmeted riders.  A bare head, often protected by the shoulders, provides the lowest risk of head contact in the event of an accident.

3.  The helmet can grab the road surface and create high rotational acceleration, aggravating brain injury.   Scientific research on brain injury found that most brain injury is caused by rotational acceleration.  Helmets cannot protect against it but they can increase it.  Soft-shell helmets grab the road, and then cause rotational acceleration much higher than the tolerable maximum.  Helmets can cause brain injury, or aggravate it.  On impact, the larger head volume amplifies rotational acceleration.  A study found that a difference of just 3cm in helmet circumference increases rotational acceleration by 150%, potentially aggravating brain injury.  The difference between a helmeted and non-helmeted head is about 20cm.

4.  There is anecdotal evidence that helmets convert what would have been focal head injuries into much more debilitating brain injuries.  This is consistent with Canadian data that shows the length of stay in hospital increased following helmet laws, from 4.3 days to 6.9 days, suggesting more severe head injuries after the helmet law.  In addition, the number of serious head injury admissions increased by 46% from 2000-2001 to 2003-2004.

Bicycle helmets are a safety trade-off.  They can reduce focal skull injuries from linear acceleration in minor accidents. However, they increase the chance of the head hitting on impact, particularly side impacts that generate high rotational acceleration, potentially aggravating brain injury.  A soft-shell helmet tends to disintegrates on impact, absorbing little energy.  This crumbling is what ironically many people mistake the helmet for as having saved their life.

A recent meta-analysis of helmets effectiveness reports that there seems to be no net beneficial effect overall from soft-shell helmets.  They protect against skull injuries in low-speed accidents, but do not protect against facial injuries, and increase the risk of neck injuries.

It is not safe to assume that the padding provided by helmets outweighs the increased risk of accidents, and the risk of aggravating neck and brain injuries.  The belief that helmets can only improve safety may be a myth.

Bicycle helmets impact on injuries

We do not know whether helmets provide a net safety benefit.  What we do know is that the helmet law has made cycling more dangerous, by increasing accidents and injuries by 50% for child cyclists in NSW.  Some of this degradation in safety was due to a reverse “safety in numbers” effect, that is not inherent to helmets.  However, it is possible that some of this degradation in safety was due to the helmet itself, either through risk compensation or one of the helmet mechanical deficiencies.

The UK’s National Children’s Bureau provided a detailed review of cycling and helmets in 2005, stating that the case for helmets is far from sound and the benefits of helmets need further investigation before even a policy supporting promotion can be unequivocally supported.

This dilemma about the trade-off between protection in minor accidents vs. risk of brain injury is what enabled an Australian cyclist to successfully challenge a helmet fine on the basis that wearing a helmet could be dangerous.  The judge agreed that the helmet could be dangerous in some circumstances, and that wearing a helmet ought to be a matter of choice.

When reasonable doubt exists about any product providing a net benefit, people should have the right to choose.

This seems hard to believe, as there have been many studies that claim that helmets protect against 60% or 80% of brain or head injuries.  However, most of these studies lack scientific discipline.  Like this one, many of those studies started from a preconception that helmets worked and attempted to “prove” it.  This is hardly scientific research.  Many of those studies were funded by the helmet industry or by the Australian government, who have a vested interest in exaggerating the benefits of helmets.

Many of the studies exaggerating the benefits of helmets make physically impossible claims.

How can a helmet reduce 80% of head injuries considering they don’t cover the face where 70% of head injuries are?

How can a helmet reduce 80% of brain injuries considering they cannot protect against the main cause of brain injury, rotational acceleration, and they can increase rotational acceleration?

How can these studies make such physically impossible claims?  Like this study, many of these studies fail to consider confounding factors, a common error in statistics.  They reach unwarranted conclusions far too eagerly.  Other examples of misleading research can be found here.

In 2000, the Australian Transport Safety Bureau (ATSB), a government agency, released a meta-analysis, that claims to provide overwhelming evidence that bicycle helmets reduce the risk of brain injury.  This claim was rebutted in 2003, highlighting a lack of understanding of brain injury.  The ATSB did not reply to the rebuttal, thus giving up on its claim.  Despite being discredited, this analysis is still used by the government to defend the helmet law, claiming that helmets reduce the risk of head injury by 60%.  How can a device whose mass adoption has led to an increase in the risk of head injuries still be claimed to reduce the risk of head injuries by 60%?  Such propaganda disregards the risks of helmets while exaggerating their benefits, ignoring the real-world consequences of adopting helmets.

In 2011, a meta-analysis re-assessed this ATSB meta-analysis.  It concluded: “This paper shows that the meta-analysis of bicycle helmet efficacy … was influenced by publication bias and time-trend bias that was not controlled for. As a result, the analysis reported inflated estimates of the effects of bicycle helmets“.

How can such misleading “studies” be justified as a form of public service?

Such deceptive studies add little to scientific knowledge, while exaggerating the benefits of helmets.  This tends to mislead policy makers towards false “solutions” to cycling safety, while neglecting more effective measures like rider training and  improving the behavior of motorists towards cyclists.  This might explain why Australia has one of the worst cycling safety record among developed countries (ref page 43).