&gt; I can&#x27;t find a reference with a short Googling, but as I recall helmets only help in a fairly narrow window, something like 18-23 mph or so<p>I&#x27;d really like a citation on that. I&#x27;m into motorcycles and while helmet design is different, every motoGP season has plenty of examples of riders tumbling at +100kph and walking away after.