Originally Posted by
Dahon.Steve
+1
I was wearing a dark gray helmet during the summer and it was hot. I stopped by a local bike shop and purchased a white Giro and could not believe how much cooler it was compared to the less expensive gray helmet. It's also possible that Giro makes a better helmet but in my opinion, the color had a lot do with temperature. It's the reason people were white colors and not black in 100 degree temperature.
However, I did purchase my first black one this winter, a Bern helmet. This will be for winter riding only and not summer.
Less expensive buys less effective-venting.
I wear white on my skin (see my pic above with white sleeves); however, the black shell of the helmet is not on the skin... there's a inch or two of polystyrene between the shell and my skin. Polystyrene is the same material used to make insulated coolers - it's not going to transfer the heat from the black shell to your scalp.
The only time a black helmet is going to be hotter is when you're not moving, and if you're not moving, take off the helmet.