Bicycle Helmet Safety Institute
The Helmet Update
Volume 30, #4, October 1, 2012
All issues index
ASTM improves bike helmet standard
ASTM has published the improved version of F1447, Standard Specification for Helmets Used in Recreational Bicycling or
Roller Skating.
The new version is the first ASTM helmet standard to use variable mass headforms for impact testing. The drop assembly
that includes the smallest child headform now weighs 3.1 kg, while the assembly for the largest headform weighs 6.1 kg.
Formerly all sizes weighed 5.0 kg, a convenience for the test technician but woefully unrepresentative of head weights in
the real world.
The greatest significance of the change is that helmets made for toddlers will have to have less dense foam in their
liners. The lighter headform will not crush very dense foam, and would just stop immediately on impact, with a spike in g
levels that represents brain injury. The less dense foam in child helmets will hopefully reduce the incidence of
concussion.
The less dense foam will occur in three other sizes as well, but the drop assembly for the large and extra-large
headforms will weigh more than the old 5.0 kg. For those sizes manufacturers will have to either use denser foam or
thicker helmets, or a combination of both. Although there was concern about the denser foam option, those helmets will be
better able to handle the impact energy of a real-world large head.
Very few manufacturers now certify to ASTM F1447. All who sell in the US market use the legally-mandated CPSC standard.
We hope that CPSC will follow suit on the variable mass headform change, improving protection for the youngest helmet
users.
You can find a summary of the ASTM F1447-12 standard on
the ASTM site or
purchase it online for $36.
Our
standards comparison has been updated, as well as
the summary
chart.