The other day on the news the weatherman was doing a study of colors in the heat. He found out that a white car was 40 degrees cooler than a black one. I guess this study would also do in clothing. Darker colors seem to absorb the sun and heat while white,yellow and other light shaded colors it does the opposite. Which is why they tell you to wear light colored clothing in the Summer. I heard that older model helmets work better at ventilating than the newer ones do. I have a outdoor hat that has a vent near the top of the hat,a mesh screen all around and it really lets the air in. Maybe the helmet makers can figure something out.