Helmet Life

[shootingstar]

I've worn helmets nearly daily during warm seasons....for 5 yrs. and over.

If I haven't crashed and the padding inside ok/replaced, that's fine for me.

Plastic, sadly does not degrade that fast. (am referring more to our non-biodegradeble garbage.)

[OakLeaf]

I assume you're referring to DesertTortoise's question and not Gypsy's.

But the CPSC standard in the USA calls for helmets to be held at a maximum of 53°C (127°F) for a maximum of 24 hours.

I don't recall that the warehouse temperatures were much above that, if at all, but items could've been stored there for much longer periods.

I don't know what temperatures have been like in your area, but the fact that you've "worn" helmets in those temperatures is no proof of anything, unless you also crashed them and they performed to specification.

Plastic DOES degrade at high temperature, or when it's exposed to organic solvents like body acids and oils and cosmetic products we put on our faces and hair. EPS is especially fragile because of the way the beads are bonded together. It's meant to be fragile. That's the point of it and how it absorbs impact. As I said to Tom way back when, all you have to do is pick up an EPS cup that's been outside for a few months and crumble it in your hands. The beads don't degrade appreciably, I don't suppose, but the bonds between them do, and those are the parts of a helmet that count.

A helmet can be had for $30 and for no more than $300. Rehabilitation after a traumatic brain injury - if you even survive it - you get the idea. I've had one concussion (with a helmet) and consider myself very lucky that I'm not aware of any lasting effects. Any time I have to guess about a helmet, I'm going to guess in favor of buying a new one. No one here has identified herself as a plastics scientist with specific experience in EPS, and given that, asking about it here is no different from guessing. New helmet. That's all.

[Dogmama]

A helmet can be had for $30 and for no more than $300. Rehabilitation after a traumatic brain injury - if you even survive it - you get the idea. I've had one concussion (with a helmet) and consider myself very lucky that I'm not aware of any lasting effects. Any time I have to guess about a helmet, I'm going to guess in favor of buying a new one. No one here has identified herself as a plastics scientist with specific experience in EPS, and given that, asking about it here is no different from guessing. New helmet. That's all.

+1. Most of us don't have long term health insurance either.

Also, consider with brain surgery they'll have to shave part of your head. So you'll look weird & probably act weird for awhile.

[Bike Chick]

A helmet can be had for $30 and for no more than $300. Rehabilitation after a traumatic brain injury - if you even survive it - you get the idea. I've had one concussion (with a helmet) and consider myself very lucky that I'm not aware of any lasting effects. Any time I have to guess about a helmet, I'm going to guess in favor of buying a new one. No one here has identified herself as a plastics scientist with specific experience in EPS, and given that, asking about it here is no different from guessing. New helmet. That's all.

Great point, Oak. My helmet is 6 years old, has been dropped several times and stays in the back seat of the hot truck when it's not being used. I've had my eye on a new Giro Atmos that matches my bike that DH wanted to get me for my birthday but I felt frivilous getting it when I already had one. Your argument justified the purchase. BTW, Giro has 15% off all their helmets through 11/29/11 with free shipping over $100. It should be here in a week

[goldfinch]

Plastic DOES degrade at high temperature, or when it's exposed to organic solvents like body acids and oils and cosmetic products we put on our faces and hair. EPS is especially fragile because of the way the beads are bonded together. It's meant to be fragile. That's the point of it and how it absorbs impact. As I said to Tom way back when, all you have to do is pick up an EPS cup that's been outside for a few months and crumble it in your hands. The beads don't degrade appreciably, I don't suppose, but the bonds between them do, and those are the parts of a helmet that count.
.

More from the bicycle safety institute folks http://www.bhsi.org/replace.htm:

Occasionally somebody spreads rumors that sweat and ultraviolet (UV) exposure will cause your helmet to degrade. Sweat will not do that. The standards do not permit manufacturers to make a helmet that degrades from sweat, and the EPS, EPP or EPU foam is remarkably unaffected by salt water. Your helmet will get a terminal case of grunge before it dies of sweat. Sunlight can affect the strength of the shell material, though. Since helmets spend a lot of time in the sun, manufacturers usually put UV inhibitors in the plastic for their shells that control UV degradation. If your helmet is fading or showing small cracks around the vents, the UV inhibitors may be failing, so you probably should replace it. Chances are it has seen an awful lot of sun to have that happen. Otherwise, try another brand next time and let us know what brand faded on you.

At least one shop told a customer that the EPS in his three year old helmet was now "dried out." Other sales people refer to "outgassing" and say that the foam loses gas and impact performance is affected. Still others claim that helmets lose a percentage of their effectiveness each year, with the percentage growing with age. All of that is nothing but marketing hype to sell a replacement helmet before you need it. There is some loss of aromatics in the first hours and days after molding, and helmet designers take account of that for standards testing. But after that the foam stabilizes and does not change for many years, unless the EPS is placed in an oven for some period of time and baked. The interior of your car, for example, will not do that, based on helmets we have seen and at least one lab crash test of a helmet always kept in a car in Virginia over many summers. Helmet shells can be affected by car heat, but not the foam. The Snell Memorial Foundation has tested motorcycle helmets held in storage for more than 20 years and found that they still meet the original standard. EPS is a long-lived material little affected by normal environmental factors. Unless you mistreat it we would not expect it to "dry out" enough to alter its performance for many years.



Of course, as we are not material scientists we have difficulty evaluating what sites like these say. However, the ANSI standards say:
ANSI: Shall not alter due to age or use, or from exposure to sun, temperature extremes or rain. Must provide warning if solvents, transfers or other additions will affect adversely. Must not cause skin disorders, nor be affected by sweat or toiletries.


I thought this report interesting, about the bike helmet maker MET:

The Italian company MET says in their 2010 catalog:
"We are often asked 'For how long is a helmet safe?', or 'how often should I replace my helmet?”' Until now it has been difficult to find any reliable figures to help answer these queries. MET have now developed a series of tests which are conducted on aged helmets to determine a 'best before' date (unless the helmet is involved in an accident. In that case it should be replaced immediately.). The results indicate that, if used properly accordingly to our owner manual, our helmets will still do their job up to eight years after they have been made. Not only is that good news for the customer, it’s great news for the environment!"

We applaud MET for undertaking an actual testing program on helmet life and for making that statement. We regard it as a triumph of integrity over marketing. MET's helmets are made with industry standard shells and liners, so there is no reason we can see that their recommendation should not be good for many other helmet brands as well. If another manufacturer comes up with a testing program that shows earlier deterioration in the protection from their products we will review this page.

In sum, we don't find the case for replacing a helmet that meets the ASTM or Snell standards that compelling if the helmet is still in good shape and fits you well.

[Catrin]

This is an interesting discussion. Not being material scientists does make it difficult to separate the wheat from the chaff. It is my personal opinion that it is better to be safe than sorry. Helmets aren't that expensive...

I used to think that having one helmet was enough, but after thinking about it, I decided to have two helmets (one for road and one for mountain biking). I figure that, if nothing else, switching them out extends their lives and should something happen to one of them that I still have one.

What I've not been able to settle is the question of possible damage to the helmet when it falls from a height when it isn't on my head - like from the trunk to the ground. Does that cause damage to the helmet? I've been to different sites but there appears to be mixed opinion on this one. So I don't put it on my trunk or top of my car these days, just in case.

[goldfinch]

This is an interesting discussion. Not being material scientists does make it difficult to separate the wheat from the chaff. It is my personal opinion that it is better to be safe than sorry. Helmets aren't that expensive...

I used to think that having one helmet was enough, but after thinking about it, I decided to have two helmets (one for road and one for mountain biking). I figure that, if nothing else, switching them out extends their lives and should something happen to one of them that I still have one.

What I've not been able to settle is the question of possible damage to the helmet when it falls from a height when it isn't on my head - like from the trunk to the ground. Does that cause damage to the helmet? I've been to different sites but there appears to be mixed opinion on this one. So I don't put it on my trunk or top of my car these days, just in case.

I've gone to two helmets too. I bought a new Bern, which is nice for tooling around town and for cooler weather. An upside is that it is the most comfortable helmet I have ever worn.

I used to ride motorcycles and the same discussion would come up on dropping your helmet and how much damage it causes. Some would say replace immediately! But I never new anyone who actually did that. It would be nice to have more data on that. I do as you do and try to put my helmet in a place where it isn't going to be tumbling down.

[OakLeaf]

Well, I do understand that the Snell Memorial Foundation has come a long way from its founding, and not all of it in a positive direction for helmet wearers. That's been hashed out ad nauseam in the magazines and the interwebs.

But they've had that five year limit for a very long time, and I guess I'd want to see something from another third party before I'd wager my central nervous system on an anecdote from a single manufacturer.

And I'd feel a lot more comfortable if someone could explain to me why coffee cups that have been outside for a while crumble, rather than just saying "they don't," when they obviously do. Maybe there's something in the environment on the ground or water, that helmets aren't exposed to much, that causes the cups to crumble. Maybe the EPS in cups is significantly different from the kind in helmets. But until I stop picking up coffee cups and having them crumble in my hands, I'm going to keep replacing my helmets every three to five years.



As far as low-level impacts - just like the holes - that's something that's really dependent on the specifics. There's no way to generalize, because no two helmets are going to land in exactly the same spot on exactly the same surface from exactly the same height. Almost certainly it's fine after one drop off the handlebars. Probably after two. Maybe after three. Inspection by the manufacturer would be able to tell you. Otherwise, it's just a gamble. (It's always a gamble, I know, it's just that the odds become a little worse each time a helmet gets dropped...)

[shootingstar]

Thanks for the info, goldfinch.

I'm not surprised..I've worked in engineering libraries where we had info. on engineering materials...which includes hard plastics.

Until my helmet crashes somewhere or gets dropped enough on hard surfaces, I'm not going to worry about it.

I've had 4 different helmets over the past 20 years of regular cycling. Right now I have 2, in 2 different cities when I ride.
Meanwhile for the anti-helmet lobby, this thread would look strange to them.

[Gypsy]

But ... how many marks, and are they on both sides? Is it possible they're the holes where a visor is supposed to pop in? My helmet has those even though it didn't come with a visor - I suppose that means Specialized sells the exact same liner in "road" and "MTB" trim.

No, these are on the back, only one side of the helmet has them, they are about 1/4 inch deep. I know it didn't have these before, it's just something I happen to notice recently but didn't give it much thought until I started reading this thread on helmet safety!

[owlice]

Okay, here's something TE members can do to help answer the burning questions about helmet life!

• Half of those of you who have purchased a new helmet: bury your old helmet in a backyard (preferably your own, or at least one you'll have access to in five years). Dig up in five years, report here on its condition.
• The other half of you who have purchased a new helmet: send it to someone who lives in the tropics and ask they keep it in their car for the next five years. Retrieve helmet in five years, report here on its condition.

Bonus points for those who then also send the helmet to the manufacturers/ANSI/etc. for examination by a pro.

On your marks... get set... go!



(Seriously, doing this for 12-24 months at a minimum might answer some of the questions on this thread. Personally, I'll replace my helmet when it gets dropped/used as intended/shows cracking or other damage.)

[pll]

Hm. I don't get what such tests would show... burying a helmet or leaving it out in a car in the sun are not intended uses of a helmet. I doubt that would even simulate normal aging of one.

Anyway, I agree with the rule of thumb: when in doubt, replace the helmet.

A while back, I did ask a faculty member in the materials science and engineering department whether degrading EPS was a concern with bike helmets, in particular within 3 years as some helmet manufacturers suggest. He said, under normal use, it was not. That does not mean I will keep the same helmet for 10 years, but I am not rushing to buy a new one, either.