How Much Safer Are Bicycle Helmets Really?

How Much Safer Are Bicycle Helmets Really?

We all know that wearing a bicycle helmet protects our noggin, but by how much exactly? According to a new Australian study, refusing to strap on a helmet can increase the chance of serious head injury by as much as 550 per cent.

Bike crash picture from Shutterstock

To determine the effectiveness of helmets in reducing head injuries and hospital treatment costs, researchers from the University of Sydney collected trauma registry data from 348 bike-riding patients admitted to seven Sydney hospitals between 2008 and 2009.

They discovered that cyclists without helmets were 5.6 times more likely to suffer any head injury than cyclists wearing helmets and 5.5 times more likely to suffer a severe head injury than their helmet-wearing counterparts.

Motorcyclists, meanwhile, were 3.5 times more likely to suffer a severe head injury when not wearing a helmet. On the surface, this seems to suggest that it’s safer to ride a motorbike than a bicycle when going helmet-free. However, we’re assuming a large proportion of the former were sent straight to the morgue and hence were not included in the study.

The report also found that the hospital costs of treating an injured bike rider was around three times higher for non-helmeted patients than for those who had worn a helmet, with the cost ranging between $33,000 and $140,000 (compared to $15,000–$60,000 for helmet wearers).

“The results add to the growing weight of observational data supporting the use of helmets, 3-5 which should therefore be considered at least as protective for pedal cyclists as they are for motorcyclists,” the report concludes.

However, they caution that the small sample size coupled with the inability to control for other incident factors (such as speed, collision details and intoxication) should be taken into account.

See also: Should Queensland’s New Bike Helmet Laws Apply To All Australians? | Helmet-Free Cyclists More Likely To Ride Drunk | Bikes On Footpaths: When Is It Lawful?

The effectiveness of helmets in reducing head injuries and hospital treatment costs: a multicentre study [Medical Journal of Australia]


  • Correlation doesn’t equate to causation. Maybe, the cyclists who did not wear helmets were more reckless and ride more dangerously/riskily compared to cyclists who wore helmets who were more cautious.

    • Which, given that helmets are mandatory, is fairly likely. If they’ve accepted the risk of breaking the law then it seems likely that they may take more risks in other areas.
      There’s also no mention of if they’ve standardised for other factors, e.g. alcohol intake – “I’m too pissed to care about a helmet.”

    • This sounds a little bit like “I don’t like the outcome of this study, so I’ll quickly think up some rationale that allows me to continue to back my otherwise unsupported opinion and dismiss this as rubbish”

      Maybe if one wants to refute a scientific study, one should do so with a scientific study to refute it. Otherwise one might prefer to head off to bible class or somewhere that thinks “faith” is more valuable than cold hard facts.

      • Being aware of and controlling for confounding variables is a basic tenet of the scientific process. The researchers themselves acknowledge that being unable to control for other incident factors means that their conclusions should be taken with caution. Before trying to sound smart, you might want to brush up on your basic reading comprehension skills.

        • So in your view any scientific study can be dismissed if someone can imagine any possible mitigating factor regardless of merit? That explains climate change scepticism I suppose.

          Well then, I postulate that people riding without helmets, being unprotected, are more likely to ride cautiously. Thus this study, foolishly based on actual measurable statistics and not my personal desire to prove a point, most likely underestimates the risk of head injury when riding without a helmet.

          A scientific study should always summarize mitigating factors and possible exceptions. Doing so does not, however, mean the findings are wrong.

        • Of course, the study is statistical and doesn’t need to show causation – that has already been demonstrated by controlled impact experiments and isn’t really contested by the scientific community.

    • That is likely to increase the likelihood of crashes but the study was on the impact of the accident. If I’m reading it correctly the number of accidents doesn’t factor into it.

      If you are saying that people without a helmet are more likely to swerve into traffic and be involved in a much more serious accident that is one thing, but I don’t think the type of person who doesn’t wear a helmet factors much in what happens when they are involved in one.

      Based on the fact the study was around head injury the number seem right. Having your head protected from a fall after being doored means you are much more likely to have a lower or no head injury compared to having your unprotected head falling towards the ground

      Edit: There is also a school of thought that people who ride without a helmet are involved in less accidents. This is from a two fold effect of them riding less dangerously because they know they don’t have a helmet and drivers providing more care around helmeted riders. I remember reading a study that drivers gave more room when passing a rider without a helmet compared to one with. Don’t remember who did it or the details so take that with a large grain of salt

      • But maybe the severity of the accident could be attributed to riding style and/or environment (farm land, park, street), as well as if helmet was worn. I’ve been cycling to/fro from work for 10+ years, and I see so many idiot cyclists, I personally think riding style has a lot more to do with severity of accident than any other factor.

        • Riding style certainly has an major impact on the severity of the accident. But I see morons with and without helmets so I’m not sure that wearing a helmet has any impact of riding style. For every risk taker who is convinced they don’t need a helmet there is a lycra warrior who thinks the helmet makes them invincible.

    • That is not relevant, given that they were only looking at the incidence of head injuries in each group, not comparing the number of helmeted v unhelmeted cyclists being admitted.

    • That is a possible explanation. Whether it is plausible, I see other people are already arguing about.

      On the other hand, other research which looked at the transition from pre-helmet-law to post-helmet-law found that serious head injuries decreased (but upper arm injuries did not) after the introduction of mandatory helmet laws. Possible interpretations are:
      * cyclists who behaved in such a way as to increase risk of head injury (but not upper arm injury) stopped riding or changed their behaviour as a result of the helmet laws
      * driver behaviour changed to specifically reduce head injury but not upper arm injury coincident with the change in helmet laws
      * helmets reduce the risk of serious head injury

      It is possible that this paper did the same thing, but I’m not at a university at the moment, so don’t have journal access.
      In any case, I would suggest the convergent evidence is that helmets reduce serious head injury (even if some cyclists who don’t wear helmets do cycle in such a way as to put themselves at increased risk of head injury).

  • There is very little reason to come to this conclusion based on these stats. The sample is wrong in so many ways.
    I could use the same reasoning about head trauma in car accidents to prove that if wearing a helmet was compulsory when travelling in a car that lives would be saved. Try suggesting that one and see if you’re not laughed into next year!

    • The difference in a car though is that you generally have seatbelts and airbags to help reduce the severity of an accident, not to mention 1-2 tonnes of metal around you. On a bike, there’s nothing between you and other vehicles/obstacles/the ground, so wearing a helmet becomes more pertinent.

      • Dman you pissed my moint. It’s about LH reporting a story without questioning the facts. The basis is flawed.

        • Our article questions the motorbike injury stats and points out the study’s numerous limitations – what did you want us to do, set it on fire and wee on it?

        • I also opened with the disclaimer “According to a new Australian study” — hardly blind acceptance here.

    • On what basis do you claim that wearing a helmet in a car would not reduce the rates of head injury?
      (i.e. your claim is based on ‘reasoning’, not data, and thus doesn’t relate to the data used for this study. Thus, it is irrelevant and best, and nonsense at worst).
      Updated: wording

  • I think the study is flawed but I don’t doubt helmets help in a country where you have to ride on the road with cars flying by.
    I’m more annoyed that you can’t ride on the footpath like we did when I was a kid. Very few kids ride bikes anymore because of this and I’m certainly not sending my kids out onto the road. My wife rides to the local school on the road with my 5 year old son on the back with trucks flying by because you are not exempt from the rule in this situation. Since it’s dangerous the local school area is a traffic jam every morning. No one else is game to ride and this is leading to a bigger health issue.
    Supposedly Australia has a high percentage of bike riders but I dispute that. The bike cage at the local large station has at most 10 bikes in it on weekdays and a few more around the station. When I lived in Japan the local bike cage for a small station had hundreds of bikes and everyone rode a bike locally.
    Here cycling only for enthusiasts.

      • Likewise anyone that is with them is also allowed to ride on the footpath.

        This also applies to many parks too where bicycles are generally disallowed.

    • Children under 12 are allowed to ride on the footpath if they want, as are older riders supervising them. I gotta say, though, when I was a kid I wouldn’t have been caught dead riding on the fottpath. That was, and remains, for wusses.

      • I would rather be a live wuss than a red smear, I guess that you have never had to dodge semi trailers & the like as i do on a daily basis to & from work….tool…

        • Most of the time I manage to dodge ’em, although I wasn’t quick enough last year and woke up in the hospital with a broken collarbone and 3 broken ribs. My helmet was split almost in half. But I wasn’t talking about now, I was talking about when I was a kid. I still don’t ride on the footpath but thrsr days it’s because dodging pedestrians makes it too damned slow.

  • If I hadn’t been wearing my helmet on several occasions, I would be definitely dead for one of them and quite possibly dead or a vegetable for the other few occasions. I love riding but sometimes accidents happen or you make a mistake. It’s just an insurance except you only need to make one payment and you have protection for a long time.

    • Likewise. Three times by my count, none of this were my fault nor were they avoidable.

      I’d rather have 3 smashed $140 bicycle helmets than a single fracture in my skull.

  • 550%!! THATS SHOCKING! Wait no, the other thing.., Meaningless.

    My bad.

  • i wasn’t wearing a helmet and Ive full split my face open above my right eye in an accident i had last year it was the day before Halloween. story go’s mid after noon i was drinking with my mate and was drinking till about 9pm n i had to go for a ride to “get” something ne who on my way back home being 10:15pm and really dark where i was riding (no bike lights) i happened to be texting while riding with no hands still drunk/tipsy i couldn’t see where i was going from the light off the phone and veered into a power poll i was doing about 30kmh. i knocked my self out and came to when i hit the ground. so now i wear a helmet 9/10 .. Docs said i was lucky i still have my eye but all in all even if i had a helmet on would i have just walked away with a scratch ???? oh btw Ive been riding bikes for 19 years and that’s the 1st head injury Ive had and it was 100% my fault …

  • Loved reading the riposte style here today! BUT on a serious note, helmets and attitude are critical considerations and here are a few small anecdotal observations as my medical friends would say:
    1. I live in a country town of 45,000 on the E.Coast of Oz. We suffer from poor, narrow roads and driving around corners was fraught with danger from the over 70’s and under 30’s.
    Then “bicycle mania” struck, a virulent dis-ease which spread rapidly from the South.
    Suddenly half the road width was taken up by a new “lane” dedicated to the 75 fanatical-cyclists in the town. AND penalties appeared for motorists straying into a maze of painted no-go zones.
    The worst effect was the new-found arrogance of these pointy-headed racing bike and space-gear wearing fanatics who seem to believe that the yellow line provided some form of immunity. They ride, often two abreast and sometimes three around corners, babbling to each other and never a wary look behind to see if a 20 y.o. or 80 y.o. is trying to negotiate that same corner while avoiding a head-on collision………
    2. HELMETS: They all seem to wear the strange-looking “racing helmets” – designed to reduce wind-drag while offering almost no serious protection in an accident as proven by a brilliant study at the Oz CSIRO years ago, resulting in the design of an odd-looking but incredibly effective protection in the almost inevitable accidents all two-wheel riders have.
    Told a Dentist friend of mine about it and he said, “WHO’d wear THAT??”.
    Mind you, he does inhale fluoride all day….

    The bicycle riding bit is fine in Holland and parts of China and Asia, but is simply a threat to life and limb for the vast majority of us voiceless, downtrodden motorists.

    Postscript: It is great exercise. I ride one at home in the safety of my lounge-room every day.

    • @himagain: Do you know where I could find that study? I’d really like to read it.
      (I tried to track it down using Google but couldn’t find it)

      I agree with you that simply painting ‘bike lanes’ on a road which isn’t wide enough for bicycles and cars can make things worse, particularly because of the impact it has on mutual attitudes between drivers and cyclists.
      It is worth pointing out that riding two abreast is legal on a road lane (although probably not where there are bicycle lanes). Also, doing so on a single-lane road where there are other vehicles may well not be legal – and fair enough, too.

      • @gnoshi
        Hi there. It was originally on an ABC show – probably “The Inventors” and the inventor was I’m pretty sure with the CSIRO.
        “Legality” is like a favourite saying of my old mentor Kylneth: “Truth is very poor armour and usually will attract arrows”
        Bike riders demanding their “rights” I believe are the cause of most accidents involving them.
        It would be a rare driver who actually targets them…….. but two abreast is really asking for it.
        I regularly have to avoid them, hurtling down a local hill near my beach a bit after dawn, in a race to the coffee shop in a gaggle of up to 30, at speeds of near 60 k.p.h.

        Bicycle riders should ride (if they must be on open roads) like porcupines make love – very, very carefully. 🙂

  • I once visited a librarian friend who worked for a accident research group who had motorcycle helmets catalogued of deceased riders. Quite macabre.

  • They discovered that cyclists without helmets were 5.6 times more likely to suffer any head injury than cyclists wearing helmets and 5.5 times more likely to suffer a severe head injury than their helmet-wearing counterparts.

    The causative question aside, surely that data indicates that the small actual cost of buying and wearing a helmet versus the massive potential cost of not wearing one makes this a silly argument.

  • All this study tells me is that if you land on your head, you’ll be better off with a helmet. Duh! What if you land on some other part of you body? The study doesn’t take into account systemic data. Comparisons to increased neck trauma due to the ‘bobblehead’ effect aren’t taken into account.
    Also changes in cyclist numbers and behaviour through altered perception of risk need to be considered to determine if the net result is in cyclists favour.

    check out more here:'s-helmet-law-disaster

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