Christophe Noel
Expedition Leader
So I'm shopping for a helmet and I found one that I like but it is offered in MIPS and without. Having MIPS is $40 more and the guy at the bike shop didn't have much to say on MIPS added protection.
I almost always use a MIPS lid. It isn't universally loved, not that it has any negatives. Some argue it is a non-benefit. Others say that you can get the same effect with...a full head of hair of all things. In effect, it allows the helmet to rotate slightly on your head, which in turn mimics the fluid in your noggin between your brain and skull. It is intended to lessen rotational forces on impact which cause a lot of trauma to your brain.
Another think I have read over the years that makes sense, some manufacturers like POC try to keep their vent holes rounded and less likely to catch on intrusions in the ground on impact. That promotes a slide across the ground. If a helmet catches on the ground, you get more rotational force, more brain injury. Same reason some motorcycle riders wear suits made of materials that slide.
Lastly...now that I've worn and tested probably 50-75 helmets over the years, there are some things that matter to me. Visors - need to be solid, adjustable if possible, and dark in color on the under side. The ratcheting adjustment system needs to be one-handed and the contacts at the back of the head need to be adjustable up and down. The pressure points on the back of your head can be very sensitive so you want that retention system to be adjustable to move the contact point.