While I am no expert, as I understand it the real benefit to MIPs is that it lessens the impact of an “angular” (vs. “linear”) blow to the head. (Think of linear as a 12 o’clock [head-on] collision vs. angular as a 1,2, 10 or 11 o’clock collision). In a head on collision the interior of the helmet absorbs most of the energy and the brain is usually not displaced very much (remember the brain is suspended inside the head). But many crashes are angular blows where the effect on the brain is greater since there is more “rotational energy” that is not absorbed by the helmet. MIPs limits the amount of rotational energy transferred to the brain from those angular impacts. The MIPs layer inside is designed to allow a very small degree of rotation from the initiation of the blow which greatly reduces any rotational energy being transferred to the brain. This site can explain it better:
Hi, I just got a new helmet with MIPS and as far as I can tell it’s basically a second, thin plastic layer inside the helmet that’s separate from the foam of the rest of the helmet. This second layer is what contacts your head and is connected to the rest of the helmet by what appear to be a few short, thick rubber bands. These rubber bands allow the outer shell to slide around and rotate a little bit, the idea being that this will lower rotational forces on the head in the event of a crash.
I’m not sure how effective this is, (haven’t crashed yet) especially considering your scalp moves in the same way.
It is decent technology, and has been proven effective on motorcycle and race car helmets. Seeing as most bike helmets, especially non full face helmets, do not fit super tight and can move around a little anyway, I don’t see enough need for it with bikes to be willing to pay extra for it. Of course, if I was a down hill guy I would be getting all the protection I could afford.
Not to get off base from the OP’s topic, but the saying “you get what you pay for” exists for a reason. Personally I have zero doubt in my mind when bombing down the trail that my MIPS helmet was a better financial investment than a Walmart helmet. To each their own
rmap01 has the general idea although I wouldn’t call MIPS a “layer”. It’s a thin piece of plastic that supposedly allows your head to rotate a bit upon impact, thereby lessening the chance of injury somehow. I have MIPS but must admit I’m not 100% sure if I fully believe the concept. If you ask me the 6D helmets look like they truly have the best design for safety….but I could be completely be wrong. It’s happened before.