The fallacy of the cracked helmet

Abstract

Intriguingly, a cracked bicycle helmet is often perceived as unequivocal proof of saving lives, but this is far from the truth. It is a sign of the helmet’s failure when the underlying styrofoam fails to compress. 

It’s a natural inclination to credit a helmet with saving us, but that doesn’t necessarily make it true. Without a helmet, cyclists get hit by cars, and the survival rates remain comparable.

It’s worth noting that our confidence in the protective power of polystyrene helmets often surpasses the stark reality. In a severe accident, these helmets frequently fall short in offering adequate protection.

Wearing a helmet can encourage riskier behaviors, increasing the risk of accidents and injury. The belief in helmets’ protective powers can foster a false sense of security.

Does the low-impact protection compensate for the increased risk of accidents?

That’s a question that deserves careful consideration.

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When we see a cracked helmet, it’s tempting to believe it’s irrefutable evidence that it saved a life. However, let’s delve deeper into the reality: a cracked helmet is, in fact, a sign that it has not functioned as intended. As experts advise, the key test is not in the cracks, but in whether the styrofoam has compressed. If it hasn’t, you can reasonably conclude that it hasn’t saved a life.

soft-shell-helmet A bicycle helmet is a piece of polystyrene covered by a thin layer of plastic.
Notice how the helmet has cracked, but the polystyrene did not compress.
This indicates the helmet failed to absorb the energy of the impact.

Polystyrene-based helmets protect by absorbing impact energy through compression. In severe accidents, they often break into pieces. If the helmet has cracked but failed to compress, it has, unfortunately, failed to absorb the energy of the impact.

It’s crucial to remember that a  bicycle helmet essentially consists of a piece of polystyrene concealed by a thin layer of plastic. This is where the problem lies – the helmet may crack, but the polystyrene might remain uncompressed, indicating that it failed to mitigate the impact.

Often, a cracked helmet has failed to work as intended:

“The next time you see a broken helmet, suspend belief and do the most basic check – disregard the breakages and look to see if what’s left of the styrofoam has compressed. If it hasn’t  you can be reasonably sure that it hasn’t saved anyone’s life.“

Correlation is not causation

Our inclination is to attribute causation based on timing. If we see a cracked helmet and remain unscathed in terms of head injuries, we instinctively link this to the helmet’s protection.

It’s a natural inclination to credit a helmet with saving us, but that doesn’t necessarily make it true. Without a helmet, cyclists get hit by cars, and the survival rates remain comparable. The majority of bicycle accidents do not result in serious head injuries, regardless of whether helmets are worn. We often overlook this, attributing a lack of head injury to the helmet:

“see the double-standard of finding it entirely logical when helmeted cyclists who survive collisions report that wearing a helmet saved their life. It is a powerful emotional argument, but logically, statistically, and scientifically, it is erroneous for the same reasons it would be erroneous to say that not wearing a helmet saved Gene Hackman’s life. If a cyclist wears a helmet and they emerge from a collision alive, that implies correlation, not causation.”

Polystyrene helmets are designed for low impacts

It’s essential to understand that bicycle helmets are designed to protect in minor impacts, not in high-impact scenarios, such as those involving motor vehicles. In such cases, the forces at play are generally beyond the protective capabilities of helmets. 

It is easy to forget that bicycle helmets are only designed to protect in minor impacts:

“In cases of high impact, such as most crashes that involve a motor vehicle, the initial forces absorbed by a cycle helmet before breaking are only a small part of the total force and the protection provided by a helmet is likely to be minimal in this context. In cases where serious injury is likely, the impact energy potentials are commonly of a level that would overwhelm even Grand Prix motor racing helmets. Cycle helmets provide best protection in situations involving simple, low-speed falls with no other party involved. They are unlikely to offer adequate protection in life-threatening situations.“

Dr Carwyn Hooper from St George’s University in London reports:

“Looking at evidence, it does not matter if people are wearing a helmet or not, any serious accident on a bike is likely to kill them”

In fact, polystyrene helmets can increase the risk of neck injuries and exacerbate brain injuries, with no guarantee of less severe head, neck, or brain injuries in a fall.

Wearing a helmet can encourage riskier behaviors

Adorning a bicycle helmet certainly instills a sense of safety and protection. However, it’s essential to recognize that this perception of invincibility can inadvertently lead us and those around us to engage in riskier behaviors. This, in turn, significantly elevates the likelihood of accidents and injuries. For instance, In Australia, cycling injuries tripled after a helmet law was introduced.

cycling_injury_rate

 In Australia, cycling injuries tripled after the helmet law.

How could the widespread use of helmets increase the risk of injuries? This can be attributed to the well-documented concept of “risk compensation.” As we feel safer, we tend to take more risks, resulting in a higher incidence of accidents.

Consider both benefits and risks

Helmets can mislead us. Cycling is inherently safe, with a severe head injury occurring once every 8,000 years of average cycling. However, wearing a helmet can paradoxically heighten the risk of accidents. Employing a device that increases the risk of accidents might not be the most effective strategy for enhancing safety. It’s ironic that a cracked helmet is celebrated as “proof” of saving a life when the accident itself might not have occurred without it.

It’s easy to be misled, especially in the aftermath of a traumatic experience. Realism about the capabilities of helmets is essential, grounded in facts. Overestimating their protective potential can, in fact, be perilous. After a severe accident, it’s too late to discover that bicycle helmets are not designed to protect against significant impacts.

Bicycle helmets can be insidious:

  1. At first, they seem to protect.
  2. However, they increase the risk of accidents and injury.
  3. They are inadequate in severe impacts..

Does the low-impact protection compensate for the increased risk of accidents?

That’s a question that deserves careful consideration.

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