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What are the reasons for and against wearing a bicycle helmet?

Does anyone know any research indicating whether using a conventional bicycle saves lives? I read somewhere that helmet increases head injury incidence somewhat due to increasing head diameter. Also there was an argument against using a helmet due to them causing more rotational neck injuries.


2 Answers 2


All things being equal helmets keep you safer. However, things are rarely equal.

This Ted Talk about bicycle issues and helmet propaganda and safety talks about increased accidents with helmets on. This may be a result of Risk homeostasis or as others have suggested is a result of increased risk taking on behalf of car drivers. Another point raised by the video shows the type of impact a typical bike helmet protects against is very particular on the crown of the head. Meaning bike helmets are not tested for front, rear, and side impacts. Depending on the accident your particular helmet may provide no, or marginally additional protection over a bare head.

On the other hand there are plenty of arguments which state the effectiveness of helmets. The Bicycle Helmet Safety Institute unsurprisingly has many studies on it's site which show how effective helmets can be. This should be expected since any safety device which does not implicitly have additional safety concerns should increase safety.

The question becomes more personal in nature when you understand both sides. What makes sense for me? What risks am I exposed to? What risks do I find acceptable and not acceptable? Most people find the risk of walking around without a helmet acceptable. At some point there is a grey area, such as riding a bike without a helmet. Then there is a clearly unacceptable area for most like playing Russian roulette.

As mentioned in the Ted Talk the health benefits of riding a bike far outweigh the risks of riding without a helmet. As such compulsory helmets don't make sense.


I'm not aware of any recent studies, but the League of American Bicyclists (formerly League of American Wheelmen) has done some studies in the past that were reasonably convincing that helmets prevent serious head injuries and save lives overall.

But, interestingly, when they crunched the numbers they decided that the health effects of riding are positive (life-lengthening) even if you don't wear a helmet, so they have (at least in the past) not advocated for mandatory helmet laws. Better to not wear a helmet and cycle than to use the helmet as an excuse to not cycle.

But I haven't looked at any of this in 15-20 years -- since last I was involved Boy Scout cycling stuff.

[Incidentally, as to whether helmets save lives, when I was helping with Scouts there were two incidents where Scouts were thrown from their bikes and landed on their heads, in both cases with enough force to crack the helmet. There is no doubt that, without the helmets (that ARE mandatory for Scouting events) the boys would have been seriously injured rather than (as they were) just scratched up.]

[It should also be noted that the most injury accidents with bicycles are between a bike and some stationary object, or simply falls. Motor vehicle collisions are a relatively small fraction. Neither of the accidents I mentioned above involved a motor vehicle, and one was on a bike path. Helmets are needed even when not riding in traffic.]

  • 1
    Excellent answer. There is no reasonable excuse for not wearing a helmet. As for whether they save lives, I have personally had one incident where I am certain I would be dead without it, and another incident where it is very likely I would be. That's all the "research" I care to do.
    – zenbike
    Jan 8, 2012 at 4:53
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    "The plural of anecdote is not evidence." There is not a single objective evidenced statement in this (accepted) answer, compare to the only other answer at this time which has several links supporting a contrary viewpoint and seems to me the better answer ...
    – Unsliced
    Jan 9, 2012 at 10:17
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    Non-hardshell bicycle helmets work by absorbing energy by crushing. If they crack straight away they have not worked. Apparently it's more than a little bit tricky to find example of helmets that have worked in an actual accident. Jan 11, 2012 at 14:26
  • @TomHawtin-tackline -- When I said "cracked", I meant that there was significant visible damage. Which is fine. The helmets held together and were still semi-wearable (though obviously no longer safe) after the accidents. Jan 11, 2012 at 16:24
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    @Daniel R Hicks It really doesn't matter if the hold together. Soft cycle helmets are supposed to work by crushing. If they haven't crushed, they haven't worked. Soft helmets that have cracked on contact, or even before, are unlikely to crush correctly. Jan 15, 2012 at 18:24

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