Originally Posted by
Retro Grouch
This topic comes up often enough that it would be interesting if somebody would do some controlled testing to determine if color, for example, really makes any internal difference in a bike helmet.
Measurements would be good. I would expect the difference to be near immeasurable however. The colored layer is separated from the head by a thick layer of "Styrofoam", an excellent insulator. With that, the wind going by the outer surface of the helmet and removing heat, and the air passing through the helmet removing heat, I don't think there'd be even a minute difference inside the helmet due to outer surface color.