Yea, yea, yea, I've heard all that "cotton is rotten" folderol. 9 days out of 10, maybe more, I'm in A COTTON T-SHIRT. When I sweat, it stays wet and then the moisture evaporates. Evaporation cools. (And I look like a person who doesn't need no stinkin' jersey, that whole reverse snobbery thing... if you look like you're not even trying, then you can't fail, right?)

You're not doing a century, even if it feels like it in the heat :-)