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