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Helmets.org

CPSC Video Clip




Summary: The Consumer Product Safety Commission has produced a four minute streaming video clip on bike helmet testing and fit. We have the testing portion.




Here is the Consumer Product Safety Commission's video clip.

Features:

  • Marking a test line on a helmet

  • The rolloff test for helmet stability

  • Drop tests

  • Dynamic chin strap strength test

Some notes about the strap test in the video:

If you watch the chin strap test (starts at about minute 2) there are several interesting details. The test uses an unrestrained weight falling down a rod for a calibrated distance and hitting a steel stop at the bottom to jerk the rod and the strap it is hanging from. The clip gives some clues to why some labs break buckles that others do not.

CPSC uses a free hanging rod, as called out by their standard. Some labs use a machine that has a rod that is restrained so that it does not sway. In the video you can see clearly that the swaying of the unrestrained rod on impact stresses the strap on one side and then the other. In fact, you can see that the helmet also moves on the headform. That provides a slightly different test than one where the rod is restrained and does not sway. The helmet may also move in one lab but a different helmet with the same buckle may not move in another. Adjustment of the strap could add variability as well.

The second clue is that you can hear the full clank when the steel weight hits the steel stop at the bottom of the rod. CPSC has no pad on the steel stop, as called out by the standard. But some labs use a thin elastomeric pad to dampen the noise of the impact on the stop. That also affects the severity of the test.

For manufacturers the answer to always passing in any lab is probably less than 5 grams of additional plastic in the buckle to handle any test variations.

The quality of the clip is about the best you could expect from a 160 x 112 size video. It is best viewed with the screen set very small.

There is no explanation of the tests on the audio track, but you can find a transcript of the clip on the CPSC site.

System requirements are mostly for a setup that can play streaming video. That often will be Windows Media Player, a "free" part of most Windows installations. Microsoft has a page on that if you need background. Mac's would, as always, be different.



This page was reformatted on: April 28, 2015.
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