| (The second in a series of 3) | | | | G's are transmitted to a head-form inside a helmet |
| Now that you've got an idea about how rigid you'd | | | | when dropped from varying heights at different |
| like your helmet to be. It's time to find which helmet | | | | weights. Basically, the harder helmets allow more |
| meets your requirements. | | | | G-force to be transmitted to your brain from a given |
| To do that, we have to know just a little bit about | | | | impact than a softer one. Snell 2005 allows up to |
| the various helmet standards, which one applies | | | | 300G's. The DOT limit is 250. The other two fall |
| where and how they compare to each other. | | | | somewhere in between, but I wasn't able to find |
| There are 4 common standards to which helmets | | | | anything that stated G limits. |
| can be held. In the U.S. it's the DOT FMVSS 218. In | | | | Interestingly enough, according to medical studies a |
| Britain it's the BSI 6658. The European Standard is | | | | brain subjected to 200G's for more than 2 |
| called ECE 22-05. These 3 are the government | | | | milliseconds is a potential problem. Depending on |
| mandated minimum standards helmets are legally | | | | personal factors such as age, health, etc., it probably |
| required to pass in those countries. A voluntary, | | | | wouldn't be fatal, but could cause permanent damage. |
| private standard is the recently updated Snell M2010 | | | | What determines how hard a helmet is, is what it's |
| which is used mostly in the U.S. as this is being | | | | made of. You can buy them with shells made of |
| written. However, changes adopted in the new | | | | plastic, fiberglass, carbon fiber or Kevlar. The shell's |
| M2010 take effect on Oct. 1, 2009 and make it | | | | job is to keep things from penetrating it and going |
| possible for manufacturers to meet both Snell and | | | | into your skull. The liner, though, is what has the |
| ECE requirements. Thus making those Snell certified | | | | most influence on how many G's your head gets |
| helmets legal for street riding in Europe. | | | | when it's hit. Liners are made of expanded |
| Each of these standards have different rigidity and | | | | polystyrene (EPS). The same "foam" your coffee cup |
| G-force requirements. Generally, from softest to | | | | is made of. It's job is to compress and give your |
| hardest you'd find DOT, then the ECE, the BSI and | | | | head that little bit of extra time (distance) to |
| Snell, which requires the hardest helmets. | | | | decelerate before coming to a complete stop. In |
| Most racing organizations will accept any of the | | | | other words, to reduce the G-force to your brain. |
| above certifications. The exception is that some | | | | At the end of the day, the best real indication of |
| European organizations don't allow DOT only | | | | how hard or soft a helmet will be is the certification |
| certification. Mostly, it's presumed, because the DOT | | | | sticker on the back of every helmet on a dealers |
| allows the manufacturer to certify their own helmets. | | | | shelf. Those that have a sticker corresponding to the |
| BFI, ECE an Snell each do their own testing. | | | | standard you've chosen are likely candidates for your |
| There is, and has been for a long time, a debate | | | | purchase. |
| about how much impact and what kind of impact a | | | | Now all you need to do is get one that fits properly. |
| helmet should be designed to absorb. One side says | | | | Fit is important not only for the sake of comfort, but |
| harder is better. The other side believes less hard | | | | for actual performance in a crash, too. I'll cover fitting |
| provides more of a cushioning effect (fewer G's | | | | a helmet in the last of these articles which will be |
| exerted on the brain) and is, therefore, safer. | | | | titled Buying a Helmet - Decision 3. |
| Helmet hardness or rigidity is shown by how many | | | | |