Having been in oddly many very different bicycle accidents of varying levels of catastrophe, I have a hard time believing that rotational forces are a real prob

Having been in oddly many very different bicycle accidents of varying levels of catastrophe, I have a hard time believing that rotational forces are a real problem and not something made up by marketers trying to sell a new widget. Helmets are approximately half-spheres which bounce and skid. Protruding elements like visors are made to break away with minimal force so that nothing can catch. The contact surface is small and the external shell is hard and slick. So where is the rotational force coming from? If you watch the video at https://mipsprotection.com https://mipsprotection.com their test scenario is the most bonkers forced thing I've ever seen. Their idea of a collision is where you are completely upside down with your feet are straight up in the air and your head straight down and you're falling onto a 45 degree incline. Screenshot: https://imgur.com/kIFN1ds https://imgur.com/kIFN1ds And besides all of that, the MIPS people talk about "10-15mm relative motion". It's hard to imagine that any random bike helmet strapped to any random head doesn't already give 10-15mm of relative motion even without MIPS.