How much impact can a helmet sustain?
 

Anyone have any data on how cycling helmets are tested or how big an impact they are expected to protect us from? I know they will not do much good if hit by a vehicle at 40 MPH and you go through the windshield or are they are only designed to protect my melon in a simple "Can't get out of my pedals" type tip over fall?

ML

Google MIPS Bicycle Helmets to see a plethora of information on helmets, testing, and what manufactures have finally done to improve helmets.

The Bicycle Helmet Safety Institute (BHSI) publishes a chart with all of the different test requirements. There is a link in the chart that goes into greater detail for the tests required by the different standards.

I was wondering if I should replace my helmet since it did scrape the ground (some, but not much) during my Palm Springs Century "Hit the Deck" moment a couple weekends ago.

My body took most of the impact (leg, arm, shoulder, hip) so I doubt the helmet was damaged, but still . . .

Note that my body also protected the bike, which suffered only a slight scuff of the bar tape in the incident!

Rick / OCRR

The only data I can provide is my experience. I have had lowsides where my helmet hit the ground gently and the outer hard shell was scratched. I continue to use these helmets. I had another crash where I landed on my head first and there was structural damage along with evidence that the straps were nearly ripped off of their mounts. This helmet I cut the straps off and broke into pieces and threw into the garbage.

Your head is worth more than the most expensive bike helmet out there so if there is any question about the helmet, I would replace it. If it was just a bump and slide it is probably fine and can be used or at least kept for a spare helmet.

Yes, I would call this a bump and slide, just very slightly scratched. I stuck my event number from the Camino Real Double over the scratches so they don't show . . .

I have "used up" other helmets throughout my cycling adventures, but this one (I think) is okay.

Rick / OCRR

I have read someplace, and I will try to dig out article, that at about a 35 mph impact, the helmet is useless since the brain's crunch against the inner skull results in an overwhelming injury.

In this type of situation, your head will smack the ground without you even knowing, because it recoils so fast.

I'm willing to bet the helmet absorbed some of it, even without showing much.

I had a similar situation and there was no damage at all shown on the outside but with close inspection, a tiny hairline crack in the foam.
That absorbed what could have been the back of my head.

So, it could be fine but I would (as the other person said) relegate it to backup duty.
Really inspect it too. Is it *slightly* non-symetrical from the top, side, front/back?
If there is even a tiny crack in the foam, realize the absorbing capability is compromised.

Don't be shy about tossing helmets. Mine was a $200 Giro but when you consider the alternatives, it's really nothing.
Besides, so many cool under $100 helmets nowadays...

Incidentally, I look for helmets with a lower rear section to protect the lower sides of the skull more.
Some are better than others with road helmets.

I wouldn't consider it useless if it stops your skull from being fractured which will only complicate the injury.

This is a compromise though that manufacturers have to make to keep the standards associations and customers happy. Testing standards require the helmets to survive something like a 300 G impact and cyclists want a helmet that isn't too big, cumbersome and dorky. The problem is that in order to survive that amount of force the and be sleek and small the helmet has to be made quite sturdy but trades off it's ability to absorb energy thus transmitting it to your head.

I can't remember off hand how many G's of deceleration your head can take but I believe on Mythbusters they harp on about anything 100 G's and up being fatal so take that for what you will. The helmet can withstand 300, your head possibly 100. With that being said plenty of people have survived crashes where their helmet split open though real world situations and a lab test are two very different things.