• At 25km an hour a helmet would fail, you'd would instead have an extended impact duration. Any decrease in the collision forces must necessarily be accompanied with a increase in impact duration. Plus the 30% increase in radius around the head would have exposed you to rotational forces that could have done serious damage. It's very lucky that you weren't wearing a helmet.

  • Sounds like in either case I'm very lucky to be alive and not done more damage than the cut to the top of my head.

    What about those expensive inflatable helmets?

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