I try to make a weekly women's ride after work on Mondays, so Sunday afternoon I fill my 100 oz LUXE up with water, wrap the bite valve in foil (so no germies from the freezer attach and freeze it. In the morning I just stuff the bladder in the pack (doesn't always zip). It sits in my black car in 100 degree temps all day but by wheels down at 6:00 it is still cool.

I never use Gatorade/Cytomax, etc in my Camelbak. Just good ol' tap water, not sure that may make a difference.