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I recently fell over while riding slowly on slippery pavement. Bruised my hip a bit and messed up my derailleur. I don't think I hit my head, but it all happened very quickly. I'm aware that helmets are only designed to protect you from one crash, and have to be replaced afterwards, but I assume that only applies if the helmet actually hit the pavement (and prevented my head from doing so). I've inspected the helmet and don't see any obvious damage, or even any markings on it from the road. Is there a way I can tell if the helmet is still safe to wear, or if I should replace it?

Gavin S. Yancey
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    If you don't REMEMBER whether you did hit your head into the pavement or not, you should inspect your head first (see a neurologist) and your helmet second. – fraxinus Jul 27 '21 at 14:07
  • Related: https://bicycles.stackexchange.com/q/3815/1342 – Ambo100 Jul 27 '21 at 19:59
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    @fraxinus Helmet? What are you talking about? (humour) – MaxD Jul 27 '21 at 20:53
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    @MaxD the (very good) point there is that not-remembering is a sign of concussion. However OP says "don't think I hit my head" which is subtly different to not remembering. – Criggie Jul 28 '21 at 03:13
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    @Criggie Just a mediocre joke (which I'm aware isn't the purpose of comments). Sorry for the confusion. – MaxD Jul 28 '21 at 04:16
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    If your neck is sore but your head isn't, I'd bet you did not hit your head because: There's a lot to be said for the human reaction to keep our head from hitting the ground. Many years ago I was walking down our carpeted stairs, wearing socks, and carrying my infant. My feet slipped out from under me. I landed on my back and elbows on the stairs - I'd clutched her to my chest and pulled my chin to my chest to avoid hitting my head. Everything hurt except my head. My neck & shoulders were sore for days from my natural reaction to avoid hitting my head (the kid was just fine, too). – FreeMan Jul 29 '21 at 16:41

3 Answers3

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If your head didn't hit the road, the helmet absorbed no impact so it will be as good as before the event.

You're not sure whether the helmet did take an impact - which is reasonable. A lot happens in a short time while crashing. So check:

  • the outside of the helmet - you know roughly what part of the helmet would have hit the ground. If there are more scratches than elsewhere on the outside, or a dent or damage to the outer plastic, then "yes"
  • your own head - if it's sore at all, or if your chin straps have bruised your chin, or your ears got yanked, then you did hit the ground, so "yes"
  • the inside of the helmet, specifically the foam. If it seems different in any area, or if you find any cracks or separation of the foam from the plastic outer then the helmet is compromised. Perhaps the fall, or perhaps it's getting old.
  • witnesses: if anyone observed the accident, a co-rider or a passer-by, it is worth asking "did my head hit the road?" which gives another viewpoint.

Separately, if your helmet is over 10 years old it's probably due for replacement. There's plenty of debate whether a helmet has a lifespan of 5 or 10 years, but over 10 and it's probably due no matter what happened in your fall.

Ultimately it's up to you - no-one here can categorically answer your question. If the helmet was damaged, suffering the same fall again will cause a higher transmission of shock, right up to 100% and possibly even beyond.

Your description sounds exactly like my experience of an ice fall. It is over amazingly quickly - you don't get time to get a foot anywhere useful, so your hip hits the deck and takes most of the impact.

The good news is that your shoulder also takes some impact, and to a lesser extent the arm/elbow on that side. In my fall, I bruised my hip badly and mild bruising on the shoulder. The elbow was scratched, but the helmet was undamaged in my fall. Yours could have been different, so check helmet closely and make your choice as a responsible adult who is liable for the consequences of that choice.

Toby Speight
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Criggie
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    Damage can be subtle - if possible also look at what your head might have hit. In my bad crash a couple of years ago I easily spotted where my helmet had hit my phone mount as I went OTB, but there was some subtle cracking where it had also hit the forearm rest from my aerobars. The armrest metal was cracked though, and clearly not from the ground, which made the impact much more obvious. OTOH when I have hit my head on a slow side-fall like that, the scuffing has been pretty obvious - but it often doesn't touch the ground at all – Chris H Jul 27 '21 at 09:40
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    I'm not sure about witnesses - it would be a nice idea, but even another cyclist looking right at you would have a hard time being certain, from most angles. A random person who's never fallen off a bike and was looking at their phone until they heard something would have no idea – Chris H Jul 27 '21 at 09:42
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    @ChrisH yeah - sadly we've all had some experience with the ground. When in doubt, replacement is the pragmatic course. – Criggie Jul 27 '21 at 09:59
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    "right up to 100% and possibly even beyond." -- really? – user1271772 Jul 27 '21 at 17:48
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    @user1271772 it's unlikely, but not inconceivable that a damaged helmet could make a crash on compressed earth or wood worse than it would be without helmet. – leftaroundabout Jul 27 '21 at 17:59
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    Re 10 years - from a safety perspective, Refer https://helmets.org/up1505a.htm - "There are reasons to replace your helmet, but simple age is not one of them." – mattnz Jul 27 '21 at 20:45
  • @mattnz Agreed - 10 years of age (sitting on a shelf somewhere) is different to 10 years of normal use. I find the foam tends to start flaking, specially at the points where I hold the helmet to put it on/off. The helmet has travelled tens of thousands of km in 10 sweaty years, that alone has an effect on the components. – Criggie Jul 28 '21 at 03:11
  • My teeth hit the road when I had an ice fall. The front of the helmet hit the road, and pushed my chin into the ground. I was convinced I'd knocked a couple out for a minute or too – SiHa Jul 29 '21 at 09:23
  • @SiHa sorry to hear that. Consider that without the brim in front, your nose/chin would have taken that initial impact directly. – Criggie Jul 29 '21 at 11:59
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    @Criggie indeed - it wasn't a complaint! – SiHa Jul 29 '21 at 14:31
  • @leftaroundabout, ...indeed, one of the anti-helmet lobby's minor/weaker arguments for a long time was to the effect of "while a helmet does reduce the severity of head-involved accidents, the increased size of head+helmet increases their likelihood". If a helmet is damaged such that one gets less severity-reduction, then that likelihood-increase cost is paid without compensation for it. – Charles Duffy Jul 29 '21 at 20:09
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    (Personally, I'm willing to pay a cost in likely-severity of a crash that does occur to have reduced likelihood of said crash, which is why I wear a helmet with lights and mirrors on it; those increase the chances of a rotational injury, but make it easier to avoid crashes altogether). – Charles Duffy Jul 29 '21 at 20:11
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This answer covers an assessing and visually undamaged helmet, the answer by @Craggie that covers how to inspect for damage.

This study indicates that the helmet is almost certainly safe to use.

MEA and collaborator Collision Analysis collected 1,500 used helmets from consumers and eliminated any that showed damage or did not have date of manufacture stickers. The helmets studied had dates that ranged from 1987 to 2013.

They crash tested them ...

There were only four that exceeded the 300g maximum threshold: three of the oldest models made to meet only the old ANSI standard, and one newer model that had been recalled. So 671 of the helmets passed the current CPSC impact performance standard.

(My bold)

So based on the results of this study, if your helmet passes a visual inspection, it will be as safe to use as before the crash.

mattnz
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    While useful, this answer should be read in conjunction with Criggie's which gives a good explanation of how to check for damage. – DavidW Jul 27 '21 at 21:15
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Although it is definitely a good idea to err on the side of caution when it comes to head protection, and a seriously crashed helmet will not give full protection anymore, there's no need to replace your helmet after each and every crash. Even if you did hit the head lightly – at slow speed and if your hips took most of the impact, then the helmet should still be good. Only perhaps a low quality helmet would crack.

Generally speaking, the “don't use after crash” rule does apply to all helmets, whether cheap or premium quality, because the squishing of the foam filling is a design feature (a fully rigid helmet would harm the head inside). So don't assume even an expensive full-face helmet will still be safe after a crash with an actual head collision. But the foam is specifically designed to squish at high-but-still-safe pressure levels. If it were too easily squished, then it wouldn't be able to properly feather against really hard impacts. So an impact that you're not even sure happened at all should not have squished the foam. Of course, it's still good to check carefully.

If the helmet is scratched a little bit on the outside, that's probably no problem. A scratch from rubbing over the pavement, without a hard impact, doesn't affect the buffer zone thickness. Only a deep scratch would compromise the shell's rigidity or lead to cracks.

leftaroundabout
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    A minor point, and not to detract from your comments, but trials riders, like skateboarders, may be using multi-impact helmets, which use a different foam liner not based on a one-time crush principle. – CCTO Jul 27 '21 at 13:57
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    @CCTO good point! I removed that remark. (Though I think many trials riders use normal MTB helmets – but the thing is, they just know very well how to catch themselves in a crash, and usually avoid hitting the head on anything.) – leftaroundabout Jul 27 '21 at 15:39
  • Is it ok to use a baseball helmet for biking? – user1271772 Jul 27 '21 at 17:49
  • @user1271772 I'd say it's worse than not wearing a helmet at all. – leftaroundabout Jul 27 '21 at 18:32
  • Is there any proof of that? – user1271772 Jul 27 '21 at 18:56
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    @user1271772 I hope not. – leftaroundabout Jul 27 '21 at 19:22
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    @leftaroundabout using crash test dummies, for example. – user1271772 Jul 27 '21 at 19:25
  • This is an example of a multi-impact cycle helmet. https://www.hedkayse.com/pages/technology – James Bradbury Jul 28 '21 at 15:08
  • @JamesBradbury interesting, though I have a hard time trusting this company if they write stuff like “researchers believe the cumulative effect of small knocks contributes to brain disease over time”... I doubt that's the kind of helmet CCTO meant. – leftaroundabout Jul 29 '21 at 20:19
  • @leftaroundabout yes it would've been nice if they'd quoted research on that. My point is more that their helmet has been independently tested to exceed normal safety standards even after repeated impacts. Yes it's different, but I thought, relevant to discussion re "don't use after crash". – James Bradbury Aug 03 '21 at 13:00
  • Similar logic is not discarding a caving helmet each time one bumbs with it into the ceiling. A major hit, however... – Vladimir F Героям слава Sep 17 '21 at 14:38