The Giro Aerohead MIPS is a superb bicycle helmet. By two orders of magnitude the best I've ever owned.It's light and fits extremely well. I hardly notice it being on my head; the main noticeable effect with the visor down is great eye protection. There's no drying of one's eyes from the cycling wind.The Aerohead is cool. I rode with it yday and today in 90 degree sunny weather and never felt hot. The airflow system works.Presumably, the Aerohead is indeed aerodynamic. Any objective exploration of aerodynamics in real-world conditions is an exercise fraught with complexity. Still. I ride a 2016 Lightning Phantom and a very much older P38/F40. So, SWB's with relatively upright seating position. I measured 0.5-1mph faster than usual on the Phantom on a known trail, on two consecutive rides.My P38/F40 aluminum seat is at a fabricator's for welding repairs of cracks. I will definitely try the Aerohead on the fully faired F40 as soon as I get the seat back; I expect its effects to be remarkable.(Keep in mind what 1mph really means. Air drag increases with the square of one's speed, and the power to overcome air drag increases with the CUBE of one's speed. For example, 22mph takes 15% more power than 21mph, for the same machine and rider. Conversely, one can decrease drag and go faster for the same watts output.)The visor feature on the Aerohead is a great idea. I've mostly ridden with it down over my eyes, with sunglasses on underneath. Yet more surface area protected from skin cancer! Yet the visor can be attached, via its very powerful magnets, to the helmet leaving one's face exposed. Might be cooler in extreme heat, and certainly useful if dusk descends towards the end of one's ride.This little beastie also looks RAD. Especially in white. Sort of a cross between an Imperial Storm Trooper helmet and a Ford Motor Company American Helmet Model No. 8.You may have to Google that last one ...