Joined: Dec 2004
Posts: 12,560
Likes: 799
From: Middle of da Mitten
Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, Bacchetta Quattro, Catrike Speed
I haven't noticed that light helmets are any cooler than dark ones. There's enough foam insulation that it just doesn't matter. What matters more is ventilation.
The light ones might be more visible to traffic, though.