Accibump on road bike. New helmet required?

March 28, 2005 12:00 PM

I had a minor accident on my road bike this weekend, and fell over whilst moving at a very low speed. Do I need a new helmet?

I was not seriously injured, just gathered a smattering of road rash and some bruises because I wasn't able to clip my feet out of the pedals quickly enough. I was wearing a helmet, and when I fell, the main point of impact was my elbow. The side of my helmet did also hit the road, but I didn't land on my head or anything like that.

There does not appear to be any damage at all to the helmet - no visible dents or scrapes - but I've heard that the structural integrity of a helmet can be compromised by even a relatively minor bump. It's a Giro helmet, something like this model, and it is about 10 months old. Is it still safe to use? Or am I better of springing for a new one?

posted by netsirk to Sports, Hobbies, & Recreation (13 answers total)

A helmet works by using the energy from a crash to deform the internal structure, thereby reducing the energy transmitted to your head. A low impact hit will not deform the internal structure much, if at all. I guess when you say the helmet hit the road, it's a judgement call on your part (since you know how hard it hit.) If it was the equivalent of just dropping an empty helmet from ~ 6 feet, then you probably do not have anything to worry about. Your best bet though would be to write Gyro and ask when they recommend a helmet be replaced.
*I am an engineer.. but I do not specialize in helmet design*
posted by defcom1 at 12:08 PM on March 28, 2005

no way will an american company do anything other than recommend you replace. otherwise, what defcom1 said. although if it were me, i'd try working out if the polystyrene (or whatever) under the hard shell outer still filled the space, because i would guess that is what deforms. on the other hand, i have enough money these days i'd probably buy a new one next time i'm in a shop.
posted by andrew cooke at 12:14 PM on March 28, 2005

Andrew is right, on both counts. You can usually push the hard plastic outer shell in only a few mm. If it goes in deeper then that, get a new helmet. (Alternatively, you can just remove the black tape on the outside rim and pull the plastic off, to see the poly(whatever) directly.

Happy Biking!
posted by defcom1 at 12:20 PM on March 28, 2005

Short answer: It's probably fine.

Long answer: This question comes up on motorcycle forums all the time, as when someone's helmet falls off the seat or something. My standard answer is this: If the helmet is no good after a minor bump, why would you expect it to offer any protection in a "real" wreck? It's probably fine. The helmet companies will try to tell you to buy another because they're in the business of selling helmets.

Disclaimer: I'm not a lawyer, doctor, engineer, or much of anything really (except another bicyclist and motorcyclist).
posted by scratch at 12:26 PM on March 28, 2005

Giro offers an excellent crash replacement policy. Take it to a shop that sells Giro and see what they can do for you. They will probably offer you a new one at a significant discount. Helmets distribute the force of an impact and also absorb the force through their own destruction. There can be unseen damage internal to the helment that may limit it's initial shock absorption in the next crash.

I replace my helmets regurally, and never keep one more than 3 years even if it never is crashed in. I'm of the opinion that my brain is somewhat valuable, and that erring on the side of safety with helmet decisions is a good thing.
posted by tumble at 12:33 PM on March 28, 2005

It's probably fine.

If the pedals are adjustable, you might want to consider reducing the release/retention tension adjustment to allow for easier and quicker release.
posted by fixedgear at 12:37 PM on March 28, 2005

If the helmet is no good after a minor bump, why would you expect it to offer any protection in a "real" wreck?

Because of:

A helmet works by using the energy from a crash to deform the internal structure, thereby reducing the energy transmitted to your head.

They're intended as single-use. If your head was barely moving when the helmet hit the ground; if it just tapped the ground; keep it. Otherwise, replace it; it's not worth scrimping on.
posted by Zed_Lopez at 12:52 PM on March 28, 2005

Aah, the age old question of: How much is your head worth? That's what I always ask new motorcycle riders when they say they're going to buy a $50 lid... I wear a $300 shoei, although I'd buy an Arai if I had an Arai-shaped head.

If the foam of the bicycle helmet was deformed in any way, you need to replace it. While it just seems like it's foam, and who cares ... foam never compresses the same way twice, and it's pretty sepcifically engineered to compress the way it does the first time to keep your noggin in one piece.
posted by SpecialK at 1:34 PM on March 28, 2005

When Should I Replace My Helmet? is possibly inconclusive given your set of facts.
posted by joeclark at 1:39 PM on March 28, 2005

Get a new helmet. It is cheap insurance. How much is a life, or your brain, worth? You could take off the outer liner and inspect the foam underneath to see if it has been compressed. I am not even sure that is a reliable indicator, but I fail to see why not. Then you can glue and tape the liner back down. It will be a big pain, the helmet probably will not look quite right afterwards, and you can not be sure that such procedure is effective in assessing the helmet in any event. Get a new helmet for $35.
posted by caddis at 2:27 PM on March 28, 2005

as with all giro helmets (to the best of my somewhat outdated knowledge) your skyla is a snell foundation certified helmet. this means that the skyla model has been put through a series of fairly rigorous testing standards to assure its ability to protect your bean. the B95 standard is slightly more rigorous than the B90 standard; your helmet is likely B95 if you purchased it recently and therefore able to withstand a significant impact from 2.2 meters onto a flat surface. there's a sticker stuck inside your helmet confirming this certification.

if your crash was as minor as you've indicated, it's LIKELY that the others who have advised you that there's probably nothing wrong with the helmet are correct. HOWEVER, others' hunches or your own visual inspection are not technically sufficient. you should follow the procedures in your owners manual in order to be absolutely certain that your helmet has retained its integrity. if you've lost your manual, a pdf version can be obtained at giro's website. their site also includes a helpful FAQ that covers this issue. basically, this info will attempt to persuade you to have an expert evaluate your helmet. i, likewise, would also advise you to NOT take the advise of anonymous AskMefiers in this regard, but RATHER take the helmet to a local bicycle dealer and have them look at it. if they are a giro dealer, and they are for one reason or another uncomfortable with your helmet's condition, they can assist you in returning your helmet to giro for crash replacement. i haven't sold bikes for a few seasons, but i've been through this process with many customers over the years; all have met with satisfactory results.
posted by RockyChrysler at 3:04 PM on March 28, 2005

RockyChrysler: i haven't sold bikes for a few seasons, but i've been through this process with many customers over the years; all have met with satisfactory results.

But have any customers ever been told that replacement is not necessary?

Any "professional helmet inspector" would be nuts to take on liability, so the answer is always going to be "replace it".
posted by Chuckles at 3:49 PM on March 28, 2005

when in doubt: send it to the manufacturer to make a determination. that's prettty much the rule of thumb we tried to abide by. i'm sure that's still pretty much the standard of care.
posted by RockyChrysler at 4:34 PM on March 28, 2005