54

I am currently testing a bunch of lights for my (slowly) upcoming head lights review. Several of the lights can be mounted to a helmet using a mounting strap, like this:

helmet-mounted light

I'm wondering if having a light mounted on the helmet impacts its effectiveness in protecting from impacts. It seems that if the light hits the ground first, it might cause the rider's head to torque at a weird angle, or rotate the helmet causing the rider to hit their head when they might not otherwise.

Is there any research or data on this, or are there any anecdotal accounts of helmet lights affecting helmet safety?

Community
  • 1
nhinkle
  • 3,883
  • 3
  • 29
  • 38
  • 1
    Yeah, the danger is that the light could catch on something or, in a head-over fall, torque the head back. Mostly this would just displace the helmet from it's optimal position, but the head torqued back (face plant) is a very dangerous fall mode with high probability of neck injury. However, the odds of such an event are very low, unless you're a gonzo rider. – Daniel R Hicks Mar 13 '13 at 11:45
  • @DanielRHicks That all depends on where the light is mounted. – Mark W Mar 13 '13 at 12:35
  • @MarkW - Yep, there are a lot of variables. – Daniel R Hicks Mar 13 '13 at 15:13
  • 1
    It was suggested to me that I do some testing with a "crash test dummy or some annoying siblings". If there's no preexisting info out there, I may have to find some way to test it out and see. – nhinkle Mar 13 '13 at 15:25
  • Why possibly compromise the only protection equipment you wear? – Carson Reinke Mar 13 '13 at 16:39
  • Imagine an impact against a flat surface directly onto the light (say, hitting a wall after going over the handlebars). Instead of the entire top of the helmet absorbing the impact, the light and its mount would press into a much smaller portion of the helmet. – freiheit Mar 13 '13 at 17:43
  • Helmet manufacturer Prowell did have a model with a rear/blinking light on top of it. It was smaller than the light pictured, but I don't think they would have included it if it adversely affected the helmet's performance. – user1049697 Mar 13 '13 at 18:27
  • 9
    I don't have time to put together a proper answer based on this, so maybe somebody else does, but... Some of the helmet testing standards (SNELL, AUS/NZ, etc) include provisions for any protrusions to break off, not impact into the helmet too much when hit straight on, etc... I think that's mainly intended for visors/peaks, but covers anything that the helmet manufacturer puts on the helmet. A light attached to the helmet by the consumer isn't being tested against that standard and probably doesn't meet that standard, rendering the helmet+light non-conformant to the safety standards. – freiheit Mar 13 '13 at 18:40
  • 1
    @freiheit: Great response. I think a more accurate statement is "the combination has not been tested to determine that it is conformant to standards, therefore it should be considered non-conformant." – mattnz Mar 13 '13 at 21:08
  • @mattnz Sure: The combination isn't tested. The standard is testing every helmet design. So the combination doesn't meet the standard because it's not tested. I was running low on characters, though. :) – freiheit Mar 13 '13 at 22:20
  • @freiheit You should have made that an answer. No character limit, unlimited edits, and it takes the same amount of time to write out (plus I think you get more reputation if you're into that sort of thing). – Shawn Mar 20 '13 at 02:57
  • There's been some research on torque and rotational injury, but I haven't seen any testing of helmets with attached lights. http://www.cyclehelmets.org/1039.html http://www.bhsi.org/hodgstud.pdf

    It seems very unlikely a light will help though, and it could make things much worse. In most cases it probably won't make much difference, but then in most cases a helmet won't make very much difference either.

     – armb Mar 20 '13 at 13:01
  • Another page with a bit about the difference between rotational injuries and impact injuries, and helmet testing: http://www.risksense.org/2012/06/14/the-myth-of-the-bicycle-helmet/ (The reference at the bottom might be useful, but I haven't followed it.) – armb Mar 20 '13 at 13:49
  • @nhinkle Lezyne, the maker of the light in your photo, has a 'contact' link on their website. I've just sent an e-mail asking if they have done or know of any scientific testing that has been done to this effect and I will post their response here when I receive it. – Yes I use MUMPS Mar 21 '13 at 14:54
  • Yes it does. The biggest problem happens when you fall. Then it can severely damage your head. At some point I wanted to get some mirrors that are mounted on the helmet and the shop guy stronly suggested against for that reason. I have no safety data on the issue though. Despite the safety issues I have and use my helmet light. Previously I had it mounted on the bike itself. Then I started biking at night in forests and got an expensive helmet light. Despite it's bloody expensive (200$), it causes some inconvenience (I can clearly feel the weight, despite the battery is in the bag). On the oth – arthur Apr 10 '13 at 14:17
  • Unfortunately, Lezyne never responded to the e-mail that I sent. If they do respond in the future, I'll come back and post the response. – Yes I use MUMPS Apr 10 '13 at 23:12
  • I would say it depends on the type of mount. If the load is spread across the outside of the helmet and the light takes a hit it's less likely. However mine has a mount that goes through the holes in the helmet and clamps both sides. I suspect this, with a levering type of hit will more easily break the helmet. However helmets are designed to be strong, and should still perform their duty of protecting your head. Just make sure the light or light mount cannot get at your head in the event of a break/crash. – Mark W Apr 11 '13 at 12:42
  • A helmet mounted light shines where you look, so when you look at drivers or other cyclists your light shines right in their eyes. It doesn't help safety for anyone when drivers are blinded, does it? –  Apr 15 '16 at 00:17

4 Answers4

19

I found something on the homepage of the Bicycle Helmet Safety Institute. They have an article about bicycle helmet lights, listing the pros and cons of them:

Summary: Lights on bicycle helmets can be useful, but must have a breakaway mount.

Especially about the breakaway mount:

The importance of breakaway mounts

The first and most important rule for mounting a light on your helmet is that it must break away readily when you crash or catch an overhanging obstacle. If it does not, you risk having your neck jerked when it snags on the pavement or tree. Besides jerking your neck, that can add to the g's of the shock to your brain when you hit pavement.

Although there are no studies mentioned how dangerous it is when the light does not fall off during a crash, some manufacturers test their lights to break away during a crash:

Only one helmet manufacturer we have spoken to provided their lab test levels, Uvex, proving that they actually have an internal standard. And the light manufacturer Jet Lites has a standard requiring their mount to break away when loaded with a 5 pound weight.

This shows that it is important that the light falls off during a crash, but unfortunately most manufacturers do not care. Which seems to be a problem:

Some manufacturers use hook-and-loop straps to hold their lights on. We have seen some that wrap through the vents and under that seemed unlikely to detach when they should have. But again, there is no standard for that.

Source: http://www.bhsi.org/helmetlights.htm

Community
  • 1
Uooo
  • 1,642
  • 2
  • 15
  • 24
6

Answer: Yes - anything on your helmet may affect its ability to function.

Remember the skiing accident that gave Michael Schumacher brain damage?

http://www.telegraph.co.uk/sport/motorsport/formulaone/michael-schumacher/10640839/Michael-Schumacher-skiing-crash-did-helmet-camera-cause-head-injuries.html

That was not cycling, but he managed to run his helmet into a rock, and the impact was focused and exaggerated by the gopro camera mount on his helmet.

Corollary: taking things off your helmet also interfere with its function.

The best example here is when the plastic outer layer gets a bit tatty or peels off completely. Some riders may elect to remove it all, leaving a foam/polystychrene head-cup that looks as before, but will fail badly.

This looks okay, but if your head is sliding down the road, the foam will simply tear rather than absorbing and time-stretching the impact.

Criggie
  • 124,066
  • 14
  • 180
  • 423
  • 1
    I rejected a gopro for kayaking as the camera on top of the helmet combined with the rather solid mount makes it a snag hazard on the rather tree-lined rivers I'm used to. Most light mounts, cheap camera mounts etc are much more likely to break in an impact. Of course that might not help much depending on the direction of the impact. – Chris H Apr 15 '16 at 06:14
  • @ChrisH Agreed - every body mount has a risk. A chest mount would be bad in a frontal impact, a shoulder/arn/wrist could catch. I suspect a good bike/kayak mount will be safer. Can use a secondary lanyard as well, with a good mounting position. – Criggie Apr 15 '16 at 06:29
  • 2
    On a white water kayak, mounting on the boat mostly sees water, but I was happy with a chest mount (which would require a very upright position on a bike). Now I have a camera on the side of my helmet with breakaway mounting (including for the backup lanyard). The same camera has a handlebar mount I never get round to trying. My helmet light uses elastic and the thinnest cable ties I could find (I snapped one catching the light on a bike rack while wearing the helmet). – Chris H Apr 15 '16 at 07:10
4

It is certainly true that adding bulk to your helmet has some drawbacks in crashes and such, and consequently warrants some concern. In the incidence of a crash, solid, small objects that are fixed to a specific area of the helmet increase the distribution of force on mounting area, instead of spreading it away from the impact site.

However, my justification has always been this: a light can prevent just more crashes than not having a light will save you once you have crashed. Essentially, by using a head mounted light, you have more freely accessible light and can therefore be more aware of your surroundings. Equally, your surroundings will be more aware of you. These two facts combine to reduce the likelihood of crashing in the first place.

Also, I like to think that landing helmet first with a light attached is just like landing helmet first into a branch or small rock. These are also likely occurrences in MTB riding, so I would assume helmets are designed with at least some thought on this sort of situation. It mightn't be the case in reality, and I haven't confirmed this with standards, but hopefully saying this will give you peace of mind.

So yes, as far as personal experience has told me, a fixed light on your helmet can potentially do some harm in the event of a crash, but in the rest of the time spent riding, lights make helmets safer, and therefore makes riding safer. Seems like a good idea to me!

Saxman
  • 708
  • 1
  • 6
  • 12
  • 3
    The evidence you've presented does not allow you to conclude that helmet-mounted lights make cycling safer overall. You've argued that they make crashes less likely but more severe. That could make cycling safer (e.g., if they made crashes much less likely but only slightly more severe) or more dangerous (e.g., if they made crashes only slightly less likely but much more severe). And, frankly, you've not even demonstrated that they make crashes less likely: a helmet-mounted light makes some kinds of accident (e.g., getting snagged on trees) more likely. – David Richerby Mar 29 '17 at 14:17
0

I think that's harsh. It's never going to be possible to exactly weigh up the balance between the additional hazard of the light on the helmet versus the additional visibility given to other road users. My fitting has a plastic screw holding a plastic bracket which holds the light. I think it's going to make a direct hit more dangerous, but not much more dangerous. When I have the light on, especially at dusk or at night it really moves overtaking traffic away from me in a very noticeable way.

Mark Barham Smith
  • 1