Six jours

Did you come up with that line all by yourself? Shall I look forward to being called an "organ donor" or a "Darwin candidate" next?

Also, do you assume that the more a fellow spends on the helmet, the more he values his head? If you see a guy with the most expensive helmet available, are you jealous that his head appears to be more valuable than yours? To you feel smug when you see someone with a bargain basement helmet, knowing that your head is more valuable than his? And if I encrust my helmet with diamonds, does that then mean I value my head far, far more than you value yours?

Or was that just a throw-away line because you don't have anything else to say?

And finally - sorry for all the questions, but enquiring minds and all - do you believe every advertisement in its entirety, or is it just helmet advertisements?

Stucky

I've seen the effects of UV on my old helmet. The outer casing is now faded and dull after many rides in 90*-107* heat (it was a cheap helmet); and that outer casing has a crack in it, from where I accidentally knocked it into a door frame while carrying it. But the only reason I don't wear it anymore, is because it looks kind of shabby now, compared to my newer helmet. Should the need arise, I wouldn't hesitate to wear it again- as the UV damage only affects the outer shell; and the little crack is also only on the shell. As long as it holds the styrofoam in place, I'm confident that it will protect my noggin as best it can.

These "systems" consist merely of a strap (to keep the helmet in place on your brain-cage); an outer shell (to keep the inner styrofoam from flying apart on impact); and the styroafoam itself (which provides the actual impact protection). It's not very difficult to determine via inspection, whether or not your helmet will maintain it's integrity in a crash.

Sure, the manufacturers are over-cautious, because we live in a litigious society; and because they have no way of knowing how intelligent/capable a given customer is- so they err on the side of cuation- which is reasonable in their situation; and I would do the same thing if other's safety were on the line (Plus, they want to sell more helmets!); but, C'mon..... this isn't rocket surgery. A small penetration or little flaw is not going to reduce the effectiveness of a helmet. Lets USE those brains which we are trying to protect, rather than blindly believing the manufacturer's [via way of their insurance company) legalese and marketing hype.

flatlander_48

Sorry for the brevity of the response, but it is inversely proprotional to the degree of B/S in the corresponding post.

Six jours

Ah. I see it was the "Don't have anything else to say" option.

flatlander_48

Personally I don't believe that. UV attacks the integrity of the plastic and weakens it. The shell absorbs a lot of the initial impact and then spreads that energy over a larger area as it passes the energy to the inner foam. However, if the shell is compromised, more of the impact will go directly to the inner foam and that's not a good situation.

I've been a motorsports fan for better than 55 years. Don't know if you have heard of the Snell Foundation, but the test and certify racing, motorcycle and karting helmets. As fas as I know, they do not test bicycle helmets, but functionally all helmets are trying to do the same things. The only real difference is the severity of the impacts. Anyway, they are a great source of information regarding head protection. From their site:
[h=4]How do helmets work?[/h]Helmets are normally comprised of four elements; a rigid outer shell, a crushable liner, chin straps or a retaining system, and fit or comfort padding. The rigid outer shell, when present, adds a load-spreading capability, and prevents objects from penetrating the helmet. The liner, usually made of EPS (expanded polystyrene) or similar types of materials, absorbs the energy of an impact by crushing. The chin strap when properly buckled and adjusted along with the fit padding helps the helmet remain in position during a crash.

Helmets work like a brake or shock absorber. During a fall or crash, a head is traveling at a certain speed. Since the head has weight and is moving, there is a certain amount of energy associated with the moving head. When the helmet along with the accompanying head impacts an unyielding object, a rock, a wall, a curb or the ground, the hard shell starts by taking the energy generated by the falling helmet (head) and spreads it over a larger portion of the helmet, specifically, the internal foam liner. The foam liner then starts to crush and break which uses up a lot of the energy, keeping it from reaching the head inside. Depending on how fast the head is traveling, and how big, heavy and immovable the object is, the faster the head slows down, and the more energy is present. In short, everything slows down really quickly. A helmet will effectively reduce the speed of the head by breaking and crushing which reduces the amount of energy transferred to the brain. The whole process take only milliseconds to turn a potentially lethal blow into a survivable one.
That description is a bit different from how the Snell people describe it. And yes, I suspect that it is more difficult than you suggest. You can't separate the shell from the foam. I would think that the only damage to the foam that you can see is if it went all the way through the helmet and you could see it inside. If it doesn't get to the inside surface you wouldn't know.

Again, from the Snell Foundation site:
[h=4]Why should you replace your helmet every five years?[/h]The five-year replacement recommendation is based on a consensus by both helmet manufacturers and the Snell Foundation. Glues, resins and other materials used in helmet production can affect liner materials. Hair oils, body fluids and cosmetics, as well as normal "wear and tear" all contribute to helmet degradation. Petroleum based products present in cleaners, paints, fuels and other commonly encountered materials may also degrade materials used in many helmets possibly degrading performance. Additionally, experience indicates there will be a noticeable improvement in the protective characteristic of helmets over a five-year period due to advances in materials, designs, production methods and the standards. Thus, the recommendation for five-year helmet replacement is a judgment call stemming from a prudent safety philosophy.
top

[h=4]"I dropped my helmet! Do I have to go buy a new one?"[/h]Generally the answer is probably not. Helmets are one-use items, but are quite durable otherwise, at least the ones we certify. Frequent dropping or spiking a helmet on the ground, or other hard surfaces may eventually degrade the helmet's performance. Similarly if the helmet falls to the ground at highway speeds unoccupied, the owner must be aware that some degradation may have occurred. In general, the real damage comes when the helmet contacts an object with a head inside. The Foundation recommends that if you are participating in an activity that requires that you wear a helmet, you avoid hitting stuff with your head. It can be difficult to readily determine if a helmet has been damaged, and the protective capabilities compromised without a thorough inspection by a trained professional. Some manufacturers may provide this service or direct you to these others that can perform these inspections. The Foundation recommends that if you suspect your helmet may be compromised, then replace it. If the helmet has been involved in an impact while in use, replace it.


As always, there are alway things that you know and things that you don't. I take enough risks as it is. This is one area in which I can mitigate much of the risk, so why not do it?

Six jours

The shell of a bicycle helmet is too thin to "spread the impact" and does little to nothing to help absorb energy. Bicycle helmets made without a shell, like the original Giro, pass impact tests as well as thinshell designs. The shell exists for two purposes: to hold the helmet together after an impact cracks the foam, and to provide a more slippery surface to lessen torsional injuries.

Eventually UV might damage the shell to the point that it is more likely to fail to hold the foam together after an impact. I am not aware of any tests that have ever been done to confirm this. But such a severely damaged shell would not be "hidden". A close look will turn up any cracks or crazing, and you can use your fingers to determine if the shell has become brittle.

Beyond that, I am not aware of any tests of any sort which have ever been done to determine whether bicycle helmets lose any protective ability as they age. All we really have is the "suggestion" of the helmet manufacturers, and it amazes me how credulous some folks are WRT doing what the marketing department tells them.

<edit> A little more research shows that I was wrong about "aged" helmet studies:

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.

And

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.

Stucky

Soitenly! I'm familiar with Snell and motorcicle helmets. MC helmets are a differtent beast though. For instance: On some bicycle helmets, the outer shell is soft and flexible- it is not designed to offer much if any protection (Even the harder shells are pretty weak- if you have an old helmet, just give it a light whack with a blunt object, and see how easy it breaks)- whereas, with a motorcicle helmet, the outer shell is an integral part of the protection. Also....

The MC helmet fits differently; as it encapsulates a much larger portion of your head; and care must be taken with it's design and construction so that the helmet itself doesn't injure you in an accident.

Most of a MC helmet's protective structure is hidden from view- and thus, not readily inspectable after a crash/it's damage not obvious.

MC helmets must take much greater forces from much more severe impacts- they are just a totally different beast than a bicycle helmet.

For a MC helmet, I would buy one of the best available; and replace it immediately after anything but the most negligible impact.

Totally different story with a bicycle helmet though- which is far simpler; and whose structure is pretty open and inspectable; and which will more than likely be called upon to do it's duty at well under 30MPH.

A bicycle helmet is just some styrofoam which is held in place to encapsulate part of your head. A motorcycle helmet is far more complex.

Hey, if your worried about the OP's little tiny penetration......just think of how that pales in comparison to the huge openings called "air vents"..... (And notice how MC helmets don't have such holes....they could be certified if they did- which is indicatiove of just how different the two types of helmets are)

Stucky

Exactly! Just like the floating chlorinator in my pool: Every two years or so I have to replace it, because it starts to disintegrate from the UV. You can easily tell when it becomes brittle and weak. Whereas my old helmet's finish may be damaged from UV now...but the actual structure of the shell is still sound. (And it would likely take decades of occasional intermittent sun exposure to truly weaken it to the point of the chlorinator, which is in the sun constantly)

Corben

Helmets I read somewhere are designed to absorb impact but only once. Dispose of helmets after accidents involving the head. Dispose the helmet after throwing it violently on the ground because you lost the race. Never buy a second hand helmet.

Corben

Here's where I read it.

rommer25

Update: I went to the doctor on Monday. I had no head injury but now I'm in a sling. I tore some tendons. Doctor said six to eight weeks of therapy. She said I can ride as soon as I feel I can do it without pain.