The Helmet Update
Volume 42 - #6 - December 16, 2024
All issues index
ASTM F1447 Standard Revised to Lower Peak g to 275
In a victory for improvement of standards the ASTM F1447 standard for bicycle helmets has been revised to lower the peak g fail point from 300 g to 275 g.
According to George Snively, one of the founders of the Snell Foundation, the original 300 g level was picked in the 1950's because cadaver research at Wayne State University showed certain severe injury at 400 g, and "we backed off 25% to have a safety margin." Recognizing that the number was much too high, early manufacturers generally designed for 200 g or less. But that eroded over the years under market pressure to produce lighter, thinner and more ventilated helmets, as well as production by a very large number of small manufacturers all over the world who assumed the standard was their design parameter.
Although far higher than we wanted it set, 275 g was the best we could achieve given ASTM's consensus procedure. In addition to ASTM's variable mass headforms, it puts F1447 ahead of the CPSC standard adopted in 1999 and never updated since. The upcoming Snell bicycle standard revision uses 275 g for most headform sizes.
The most publicized efforts to improve impact standards are concentrated on standards for managing rotational energy. But progress has been slow as many elements remain to be pinned down, and results are often wildly variable when a given helmet is impacted at different sites.
Given a choice, BHSI would also like to see F1447 improved by lowering the test line, adding a low impact test, adding a rebound (COR) test. There is of course more on that
on our website.