Helmets - When to replace?

[Derf]

The issue is not about the type of styrofoam, but where it is.

On a snowboard, the imapct goes like this: ice/tree/whatever -> helemt (styrofoam) -> head

In a car: other car/wall/whatever -> bumper (styrofoam) -> bumper shocks -> frame -> seat/seatbelt -> you

When snowboarding, you helmet is your ONLY protection from the impact (unless you have a big high density afro). In a car, there are lots of things to absorb the impact. The quantity of styrofoam matters also. A helmet is maybe 1" thick and a bumper is 6"+ (I don't really know, just extrapolating).

So the role of the styrofoam is the key here.

[Maciek]

Folks,

Styrofoam in cars is not for safety. It is there to silence body that otherwise causes noises.

The real safety in bumper is bumper. Cover is for appearance, styrofoam is as a filler to fit snugly.

For example Acura has styrofoam in fenders (if you open doors you will see that black styrofoam surfaces.

You can think of it also as thermal insulation if you wish ;)

The actual constrauction of modeern car bumper is high density plastic absorbing impact (no bubbles - it is not a foam). Then there are metal reinforcement, subframe that absorb the rest.

As far as helmet I belive that outer plastic prevents punctures and inner styrofoam is to abosrb energy. However it is not even close to energy of car impact. A similar role of styrofoam as it is in helmet, in car is played by airbags.

Anyway that's science. My helmet wa used for 6 years and then 2 years spent in storage because I did not have chance to go to slopes. It is in acceptable condition, but I share point of view that what I se does not mean I would get. And yes it is better than nothing, but since we do not have snow here in TriState then why to wait with purchase or until I notice that: "I should have changed that helmet so I would not have that fracture". I will keep the old one for backup like you, guys, suggested... as long as I have room for all my backups for different activities :D

[dano]

Why replace helmet every five years?

The five year replacement recommendation is based on a consensus by both the helmet manufacturers and the Snell Foundation. Glues, resins and other materials used in helmet production over 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.

Most manufacturers now recommend that helmets be replaced after five years, but some of that may be just marketing. (Bell now recommends every three years, which seems to us too short. They base it partially on updating your helmet technology, but they have not been improving their helmets that much over three year periods, and we consider some of their helmets since the late 1990's to be a step backwards, so we would take that with a grain of salt.) Deterioration depends on usage, care, and abuse. But if you ride thousands of miles every year, five years may be a realistic estimate of helmet life. And helmets have actually been improving enough over time to make it a reasonable bet that you can find a better one than you did five years ago. It may fit better, look better, and in some cases may even be more protective.

This was informative too, but no info on "aging".

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V2X-48XCG8D-1&_coverDate=10%2F31%2F2003&_alid=503945567&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=5714&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=faaf01041a0a0a8aa6027f12a7b52f9a