The “Peltzman Effect” In Cycling: Could Helmets Really Encourage Cyclists To Take More Risks?

In February 2022, a London-based bike-taxi service called Pedal Me banned their cyclists from wearing helmets.

“People that are taking risks that are sufficient that they feel they need to wear helmets are not welcome to work for us,” tweeted co-founder Ben Knowles.

Knowles’ argument has long been debated in psychology as the “Peltzman Effect”.

The Peltzman Effect: the idea that safety precautions (such as bike helmets) cause you to behave more dangerously, actually making you less safe.

When applied to cycling, this theory doesn’t pass our stress test.

In this article, we’ll be disproving the idea that helmets encourage cyclists to take more risks, and learning about how helmets keep you safe on your bike.

We’ll cover the following:

  • What is the Peltzman Effect?
  • Do Safety Measures Really Make You Less Safe?
  • Does Wearing A Helmet Really Encourage Cyclists To Take More Risks?
  • Why Wearing A Helmet Makes Cycling Safer
  • Final Thoughts On How To Make Cycling Safer

Ready to learn about the Peltzman Effect in cycling?

Let’s get started!

The "Peltzman Effect" In Cycling: Title Image

What is the Peltzman Effect?

Risk Compensation Theory is the idea that people behave according to the level of risk presented.

For example, you might walk more carefully while carrying your favorite (and very expensive) glass vase, than if you were walking without the risk of dropping the vase.

In the 1970s, the US government began introducing laws requiring drivers and passengers to wear seatbelts to reduce the number of people dying in car crashes.

In 1975, American economist Sam Peltzman published The Effects of Automobile Safety Regulation, in which he used Risk Compensation theory to argue that this would actually increase the number of car accidents.

Peltzman’s logic went that with the addition of seatbelts, drivers would be safer from dying in car crashes, so would take more risks while driving, which would then increase the number of accidents.

This became known as the Peltzman Effect.

Later, when the UK was introducing its own seatbelt mandates, John Adams published a study and report which also used Risk Compensation to argue against the introduction of seatbelts.

The Peltzman Effect is basically a form of the Perversity Thesis, which argues that regulations can actually cause the opposite of the desired effect, and is used to defend the status quo.

When applied to cycling, Risk Compensation Theory, the Peltzmann Effect, and the Perversity Thesis all suggest that cycling without your helmet can actually be safer. When you don’t wear a helmet, you have to cycle more carefully to avoid a dangerous accident.

But is there actually any truth to this?

Two cyclists ride through a US city without helmets.

Do Safety Measures really Make you less safe?

In short: no.

Here at BikeTips, we’re all about the facts and data. And the fact is that even if the Peltzman Effect might seem to make sense in theory, it simply isn’t supported by data.

Later evaluations of Peltzman’s original study have found numerous statistical errors and evaluations of Risk Compensation Theory and the Perversity Thesis found “less than half” of the regulations’ effects were offset by riskier behavior.

Peltzman may have helped popularize his theory, but the same basic logic has been used to challenge safety measures by Libertarians as far back as the 1800s.

When Peltzman and Adams wrote about the introduction of seatbelts, their ideas were disproven by the data. One academic went as far as to say that Risk Compensation Theory “commands about as much credence as the Flat Earth hypothesis.”

A 2007 study found the introduction of seatbelts in the US significantly reduced motor accident fatalities for both drivers and pedestrians. Moreover, a 2003 study found that seatbelt legislation had no effect on driving behaviors, and that seatbelt laws “unambiguously reduce traffic fatalities.”

If you’re interested, Risk Compensation Theory has also been explored in making skiing safer and combating the Covid 19 pandemic.

Spoiler alert: in both cases, it was concluded that safety measures really do keep people safer.

A woman in a black jacket puts on a black bike helmet.

Does Wearing A Helmet Really Encourage Cyclists To Take More Risks?

The short answer: again, no.

To explain this we’re going to disprove two cycling myths with two cycling truths:

Truth #1: Wearing A Helmet Will Not Make You Cycle More Dangerously

This is about busting the Peltzman Effect myth that wearing your helmet will make you cycle more dangerously.

A study investigating exactly this idea involved two groups of cyclists: those who commonly used helmets, and those who did not. The study monitored the helmeted cyclists as they cycled without their helmets, and visa versa.

The results found that cyclists who were used to wearing helmets cycled more cautiously when cycling without their helmet, whilst no change was observed in cyclists who did not regularly wear a helmet.

This can be explained by causality: cyclists who habitually wear their helmets are naturally more cautious, whilst cyclists who choose not to wear helmets are less risk-averse.

Those who are naturally more risk-averse choose to wear helmets, and cycle more carefully when they’re not wearing one. Cyclists who are more likely to take risks are less likely to wear helmets anyway, and thus don’t change their behavior, helmet or not.

In other words, cycling with a helmet does not make you cycle more dangerously.

Truth #2: Wearing A Helmet Makes You Safer

This graph maps the number of fatal cycling accidents against the rate of helmet usage in various countries. By comparing the United States and the Netherlands, you might come to the conclusion that cycling helmets have no effect on cycling deaths!

But this is another causality issue.

Due to lack of cycling infrastructure and support, the US is statistically more dangerous than other countries to cycle in.

Meanwhile, the Netherlands is something of a cycling utopia. It has an enormous cycling culture and associated bike infrastructure, and was tied first as the safest place in the world to cycle in a recent study.

As it is incredibly safe to cycle in the Netherlands, many Dutch cyclists do not wear helmets. Alternatively, as it is comparatively more dangerous to cycle in the United States, many more US cyclists wear helmets.

So the helmets are a response to the amount of danger present, and do not increase the amount of danger.

And helmets are a reasonable and appropriate response to the amount of danger present, because the fact is that helmets make cycling safer.

Two cyclists wearing helmets ride mountain bike through the Yorkshire countryside.

Why Wearing A Helmet Makes Cycling Safer

This isn’t rocket science.

Wearing a helmet while you cycle helps to prevent injury, and studies have shown over and over again that helmets make you safer when you cycle.

This breakdown of injuries and probabilities shows that if you have a bike accident and you’re wearing a helmet, you are:

  • 51% less likely to suffer a traumatic brain injury
  • 31% less likely to break a facial bone
  • 44% less likely to die

There is no reason to think that cycling with a helmet will change the way you cycle – especially if you’re aware of the supposed Peltzman Effect!

And yes, while many cyclists in the Netherlands do not wear helmets and still enjoy a comparatively high level of safety, their safety is attributed to a host of other factors – and they’d be even safer if they wore helmets!

There is simply no legitimate argument to support the idea that not wearing your helmet could ever make you less safe on your bike.

So, you absolutely should be wearing a helmet when you ride your bike!

A group of cyclists in black and pink jerseys ride through a city in the afternoon sun.

Final Thoughts On Cycling Safer

In 2017, Olympic cycling champion Chris Boardman was criticized after being filmed cycling without a helmet.

Boardman was frustrated by the reaction because he didn’t want the cycling community to “fixate on to a topic that isn’t even in the top ten things that will really keep cyclists safe.”

As cyclists, we need to be careful not to focus entirely on helmets when we talk about safety, because this shifts all the responsibility of keeping cyclists safe solely onto cyclists themselves.

When really drivers, cyclists, and pedestrians alike are all responsible for making cycling safe for everyone.

So, we wanted to end this piece by moving away from the helmet debate and acknowledging the other ways we can collectively make cycling safer:

  • Encourage more people to cycle more often, foster cycling culture, and make cycling in numbers more viable and safer.
  • Investment in cycling infrastructure, such as expanding networks of segregated cycle paths and cycle lanes for a safer and more enjoyable cycling experience.
  • Enforce a higher standard of safe driving.
  • Encouraging a culture of safe and responsible cycling within the community – don’t let your cycling mates get away with bad or unsafe behavior!

And whilst wearing a helmet isn’t the only thing you need to do to ensure your safety, it certainly doesn’t hurt!

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Riley Nicholas

Riley Nicholas

One of BikeTips' content creators, Riley spends most of his time on a bike battling the hills of the Chilterns or winds of North Cornwall. Off the bike you're likely to find him writing about cycling or reading about everything else.

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