I know in theory a white helmet should be cooler as it does a better job of reflecting the sun. Anyone tried both and noticed any significant difference?

The thickness of the polystyrene would insulate any effect of colour on the outer shell.

Thats what I was thinking. I’ve got a 5 year old black Giro Hex that need replaced. I love the fit but its really hot in the summer. I was going to get a white one but may get something better vented instead.

I’ve got one of each, worn in equal measure, makes no difference.

Giro hex doesn’t have the venting of the xc lids, I use a giro athlon most of the time in summer, and a xen when I am doing stuff more likely to end in tears.