Bicycle Helmet Standards: A Summary
Summary: A basic explanation of bike helmet standards and what they can do for you.
How Do Standards Make a Difference?
Standards are useful to consumers to cover the performance you can't judge for yourself in a bike store--mostly impact management and strap strength. A standard sets minimum requirements, but does not tell you how far a manufacturer exceeds requirements. So a standard sticker inside a helmet does not necessarily tell you whose helmet is superior, but it tells you that the helmet always meets the minimum requirements.
2. Whose standard is best?
- The CPSC standard is a legal requirement for any helmet manufactured for the US market. It was adopted by the US Consumer Product Safety Commission, and is mandatory for all helmets manufactured for sale in the U.S. after 1999. It was based on the ASTM and Snell standards below. It requires dropping the helmet 2 meters in the flat anvil test.
- ASTM is the American Society for Testing and Materials, a standards setting organization. An ASTM sticker indicates an adequate helmet too. Some are certified by the Safety Equipment Institute, an independent non-profit, others only by the manufacturer. To meet ASTM a bicycle helmet also has to perform in a 2 meter drop on the flat anvil.
- The Snell Memorial Foundation sets a somewhat higher B-95 standard with a 2.2 meter drop, but most helmets with a Snell sticker meet only their earlier B-90 standard, with a 2 meter drop comparable to ASTM. Snell tests helmets independently to certify them and retests samples bought in stores.
- The old ANSI standard died some years back. It was too easy to meet. ANSI has replaced it by adopting the ASTM standard.
3. What does that mean for my promotion program?
On our Inexpensive Helmets page you will find inexpensive helmets that meet the CPSC standard. For more info on quality, check the latest Consumer Reports article. Any helmet certified to the CPSC standard meets the legally mandated U.S. Government standard. That should help to cover program organizers from the legal point of view.
4. What are the tests the standards are based on?
- Lab Drops: the helmet is strapped on a headform, turned upside down, and headform and helmet are dropped in a guided free-fall onto an anvil. Instruments in the headform measure how many g's of force the headform suffered when it came to a halt. At 400 g's you can expect permanent injury. At 300 g's you can expect to lose consciousness, and probably suffer some injury which hopefully will not be permanent. That is, assuming you are blessed with a brain with average resistance to shock.
- Strap Strength Jerk: a rod with a hook at the top is hooked over the helmet strap. A weight with a hole in the center slides up and down on the rod. For the test the weight drops down the rod for a measured distance until it impacts a stop at the bottom, giving a measured yank on the strap.
- Rolloff: The helmet is strapped on a headform. The headform leans forward as if the rider were looking down at the ground. A line with a hook on one end is hooked under the front edge of the helmet, running over the helmet, over a pulley behind it and down to a weight hanging at the other end. The weight is lifted and dropped, giving a measured yank on the helmet. The helmet must not come off. Bear in mind that this is a smooth magnesium dummy headform, not much like a real human head, so this test is not one of the better ones.
- Coverage: how much of the head does the helmet have to protect?
- Certification: Who certifies that the helmet meets the standard? Can you trust them?
5. How do they compare?
| Requirement | CPSC | ASTM F1447 | Snell B90A | Snell B95 |
|---|---|---|---|---|
| Drop height on flat anvil |
2.0m | 2.0m | 2.2m | 2.0m* |
| Drop height on hemi anvil |
1.2m | 1.2m | 1.3m | 1.3m* |
| Drop height on curbstone anvil |
1.2 | 1.2 | 1.2 | 1.3 |
| Drop rig mass for impact tests |
5kg | 3.1 to 6.1kg | 5kg | 5kg |
| Total energy** | 98 J | 90 J | 100 J | 100 J |
| Failure threshold |
300 | 300 | 300 | 300 |
| Coverage vs. CPSC | Same | Less | Same | More |
| Strap yank (Joules) | 24 J | 24 J | 24 J | 24 J*** |
| Rolloff test | Yes | Yes | Yes | Yes |
*Snell B-95 uses a more severe impact for initial certification than for follow-up performance testing,
2.2 for flat anvil and 1.5m for hemi and curbstone.
**adult test on medium headform, flat anvil. Certification
for Snell B95 is 110 J.
***Snell considers the B-95 strap jerk test to be roughly equivalent to the B-90A test, although parameters have changed.
We have lots of detail on each of these parameters on our long helmet standards comparison page
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