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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.