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?
20If 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.– fraxinusJul 27, 2021 at 14:07
2@fraxinus Helmet? What are you talking about? (humour)– MaxDJul 27, 2021 at 20:53
14@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, 2021 at 3:13
1@Criggie Just a mediocre joke (which I'm aware isn't the purpose of comments). Sorry for the confusion.– MaxDJul 28, 2021 at 4:16
1If 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).– FreeManJul 29, 2021 at 16:41
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.
4Damage 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 HJul 27, 2021 at 9:40
6I'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 HJul 27, 2021 at 9:42
4@ChrisH yeah - sadly we've all had some experience with the ground. When in doubt, replacement is the pragmatic course.– Criggie ♦Jul 27, 2021 at 9:59
2"right up to 100% and possibly even beyond." -- really? Jul 27, 2021 at 17:48
3@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. Jul 27, 2021 at 17:59
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.
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.
7While useful, this answer should be read in conjunction with Criggie's which gives a good explanation of how to check for damage.– DavidWJul 27, 2021 at 21:15
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.
8A 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.– CCTOJul 27, 2021 at 13:57
2@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.) Jul 27, 2021 at 15:39
Is it ok to use a baseball helmet for biking? Jul 27, 2021 at 17:49
1@user1271772 I hope not. Jul 27, 2021 at 19:22
2@leftaroundabout using crash test dummies, for example. Jul 27, 2021 at 19:25