HYPERR wrote:Ryethil wrote:First of all, the outer shell is usually a polycarbonate that degrades with time. Polycarbonates also don't react well to many chemicals that helmets come in contact with. This has a lot to do with various waxes and other chemicals might use to gloss your helmets. Forget paint. It might just be normal household chemicals that seem innocuous enough. The outer shell may look perfect to observation but it could shatter in a crash from age alone. I don't know anyone that can tell how well the shell is holding up from eyeballing alone.
The premium helmet manufacturers like Shoei and Arai do not use polycarbonate in their shells. They use an highly advanced FRP. You can wax the FRP shell anytime you want with no harm to it whatsoever. In fact the Shoei website highly recommends you do that.
That being said, lets now go back to the polycarbonate used in the less expensive helmets. Wax or any of the majority of household chemicals that your helmet may or may not come in contact with, will not harm polycarbonate. Polycarbonate is an incredibly tough plastic that is severely impact resistant and under normal useage will irrefutably maintain that characteristic for the life of the helmet owner and beyond; through drastic temperature variations as well.
You don't think polycarbonate is tough? Then consider that one of polycarbonates most famous incarnation is what is known as "bullet proof glass".
Polycarbonate's structual integrity cannot be compromised by coming in contact with most "household" chemicals including: Acetic Acid, Hydrochloric Acid, Citric Acid, Mercury, Methane, Ozone, Methane, Sulfur, Ammonia, Butane, Ethylene Glycol, and Ethanol.
The modern motorcycle helmet shell is not going to deteriorate to the point it will shatter from "old age" within a reasonable(or even unreasonable) time.
I already misunderstood a post today, so I'll try to be more to the point.
Shoei's website entry on helmet maintance:
http://www.shoei-helmets.com/Maintenance.aspx
I read their maintinace tips and didn't draw the same conclusions. They say to use a "specific" for helmets cleaner and wax. And they have always said to apply this helmet wax because ozone can attack the outer shell material.
As for FRP it is a type polycarbonate and this is a good thing. Previously used material was fiberglass and fiberglass doesn't deform and sends more shock through the outer shell. It also ages and shattered more easily.
What they said about care of the interior I know to be true and cleaning of the inner lining must be very carefully done with very "neutral" cleanser and sun dried. This hasn't changed for the inner lining is very subject to all sorts of chemical and excess sweat attacks.
Finally they said the possible accidental and not so accidental conditions that would effect the helmet's continued usefulness. They spelled it out pretty well. I think they left out two important conditions as well. I wear mine usually quite a bit for 7 days so it's usually soaking or drying all 7 days. The second one is how many times have I dropped it onto a surface of various hardness or bumped it carrying it around. I don't use it as a prop to keep my bike upright in soft ground but I'm not all that gentle when I'm carrying it or transporting it.
I religious maintain my helmets and yet I don't feel gualified to determine just by eyeballing a helmet what it's condition is.
I called the Arai rep and got him to admit that while they have made strides in creating new ways to have the helmet deform in a crash (YEA!) they really haven't changed the maintinace conditions that much in the last 10 -15 years.
I'm not going to talk about cheaper helmets except to say anything is better than nothing.
I guess the rest is up to you. In my job I've been at more than one accident site where the rider's hemet was seriously gouged to deep into the inner lining and others where the outer lining shattered. Not all of these were cheap and I have a better sense of which helmets I want.
Actually, none of this matters if you don't fall down. As for how long you keep you're helmet is how long you feel safe wearing it.
I'm not trying to burst your bubble but while 6 years of being a paramedic hasn't slowed down my own riding. I don't want to pickup some dead biker who just pushed it a bit to far. And like I said before, the helmet can protect the head which will look good in an open casket funeral. If the biker isn't wearing other things to keep his bod in one piece than he might as go around helmetless.
"On Monday it was fine to wear, but on Tuesday it wasn't safe any more... "
