@@Championhelmets The RPHA 91 is much larger and heavier than the 90S. Also, the 90S is more aerodynamic. The RPHA 91 is slightly more comfortable to wear. But neck fatigue sets in fairly soon, and the helmet is not nice to wear after some time. I actually found a new carbon 90S that was on discount due to being discontinued. And am very happy with it. Helmets are getting too big and heavy due to the new ECE standards.