Is It Time To Replace Your Bike Helmet?

How do I know when it’s time to replace my bike helmet?

Your bike helmet is the most important piece of protection you own.  According to the International Bicycle Fund, about 75% of bicycle related deaths come from head injuries.  We all understand that we should be wearing a helmet while riding, and I think most people are aware that they have to be replaced sometimes to ensure our safety.  However, there sometimes seems to be some confusion on just when exactly we need to replace our helmets, and why we would need to do so.

I like to tell people, as a rule of thumb, that if they are unsure of the condition or safety of their helmet, then they should just replace it.  If you can’t remember what has happened to your helmet over the years, then for peace of mind, just get a new one.

Have you crashed while wearing your helmet?

When most people purchase a helmet, they should be educated that they are only good for one crash.  The reason for this is that the EPS (Expanded Polystyrene) foam that modern bicycle helmets are made from absorbs impacts by allowing the walls of the foam cells within the foam to crush, slowing the head down and spreading the impact over a greater area.  Once the EPS foam has crushed, the helmet is no longer able to absorb more impacts.  This is the reason why we need to replace our helmet after we crash, and it is also the reason why we recommend EPS foam helmets.

Helmets that contain soft foam liners to protect the head will compress and store energy (picture a coil spring), rather than dissipate it.  On rebound, much of that energy is sent back into the head.  Though they do offer some protection in the form of a hard shell protecting the head from being wounded, they are detrimental to the rider by increasing risk of concussions.  If you are currently riding with that style of helmet, I recommend replacing it with an EPS foam one.

You probably won’t need a new helmet after every crash.  A tiny tap on the head won’t hurt much, but if the impact to your head was enough to make you feel that the helmet actually did something, then do yourself a favor and replace it before your next ride, even if the damage isn’t really visible.

Does my helmet have a best before date or shelf life?

You may have heard that helmets have a shelf life, or that they will need to be replaced based on their age alone.  This is good practice (better safe than sorry!) but is not actually based on fact.  Most manufactures will recommend that you replace their helmet after 3 to 5 years, but this is probably a very conservative figure.  The Italian helmet manufacturer MET has this to say on their website:

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*. 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!

* Unless the helmet is involved in an accident. In that case it should be replaced immediately.

So the truth may be, that as long as you have not mistreated your helmet, it will keep you safe.  In my personal practice, I replace my helmet once every two or three years, unless of course I have crashed in it.  I base my judgment on how I have treated my helmet, after having been kicked around and dropped a bunch, I always feel safer knowing my lid is fresh.  The Snell foundation knows a lot about helmets, and this is how they address the matter:

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.

What do the stickers inside your bicycle helmet mean?

Look inside your current helmet, and check to see what standards sticker it has inside.  If it does not have an CPSC, ASTM or Snell Approved Sticker inside, than throw it out and buy a new one.  Modern helmets that meet the ASTM or Snell requirements have been tested and deemed safe.  Believe it or not, you will find some helmets that are made of EPS foam and have a hard shell, and yet on the inside have a sticker saying simething like “Not a Helmet!” *, though most of the time their just won’t be a sticker at all.  These are helmets that were either tested and failed. or were never tested at all.  My advice would be to stay away from them

* My friend bought what he thought was a snowboard helmet at a local board shop that he thought looked good and fit well, but after wearing it few times noticed that there was a sticker on the inside stating that “This is not a helmet.”  By look and feel, it was just like any other helmet, but was clearly not approved by the required agency.  He returned it and bought an approved helmet.

Does your helmet fit properly?

Helmet fit is another very important factor in head safety.  Make sure your helmet fits, this is best done with the help of your local bike shop. General guidelines are that the helmet rests flat on the top of your head, and sits level.  Make sure the chin strap is in a proper position under your chin, and the strap splitters are resting just under each ear.  Some less expensive helmets are a “Universal Fit”  and adjust to any head size, others are sized Small, Medium, Large, etc.  Helmets should fit snug and not rock side to side when moving your head.

When testing helmet fit a test I always like to perform is, with the chin strap undone, tilt my head forward towards the ground.  It should stay on your head, even with out the chin strap done up.  If it slides forward and drops right off, than that helmet is probably no a good fit for your head.

Adults helmets should fit the same from one year to the next, but children’s heads are still growing, so parents should pay extra attention to how their child’s helmet is fitting and replace it as necessary.

Resources:

• Bicycle Helmet Safety Institute
• Snell Foundation
• International Bicycle Fund

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