I'm sure people have talked about this before but i thought i'd post today's experience out on the trail with 2 polars i took with me..
Anyways I filled the blue logo polar bottle with 6 ice cubes (full cubes, not the thin ones) and then use cold water out of the water tank we have (it cools about 3 or 4 cups worth something like that).. Then i filled the red logo bottle with 4 ice cubes and pretty much room tempature water.. about 25 to 30 (maybe 35 minutes) into the ride the red bottle had no ice left, but the water was pretty cold/cool.. it wasn't the hottest day, about anywhere from 75 to 80 (the tempature gauge on my bike computer isn't the most accurate).. and i was in the sun for about 50% of the ride (the first half).. anyways at this time i checked the blue bottle, and it still had a GREAT deal of ice still in it.. So further on down the road about 1hour into , the red bottle was a little warmer, but the water was still cool, and definatley drinkable.. the blue one, still had a good amount of the cubes left, probably 3? at about half size.. Not bad!.. Anyways even later on i get to the 15 mile marker (about 1 hour and 20 minutes or so).. and the blue bottle has now pretty much melted the ice away.. but the water was still as cold as it was with the ice nearly.. at the 25 mile mark (5 mile away from home and about 1 hour and 40 minutes into it) the blue one was still pretty cool/cold.. both were extremely drinkable the whole way.. neither of them got NEARLY as warm as my old trasnparent water bottles..
Anyways I didnt max out how much ice i could put in these, i guess i thought it would keep them cooler and i wouldn't need much ice, and i didnt want to drink all the water and still have a bunch of ice in there i could drink.. That was not a problem at all.. These bottles are not magic, the ice does still melt.. but the BIGGEST factor here is make sure you put VERY cool water into them with the ice, it makes the ice last much much longer.. I can probably fit 8 maybe 10 icecubes into the bottles, and on an 80 to 85 degree day, i think that might make them last 1 or 2 hours.. I think this bottles do pretty much what they advertise, and make the water much more drinkable then regular bottles.. (my regular transparent bottles would have both the ice melted in the bottles (fully filled with ice that is) in less than 30 minutes.. and the water would be warm after 1 hour..
I definatley think these bottles are worth the 9 bucks a peice i paid for them (REI).. I also got the grey french one, isotype or something i cant remember the name, I haven't tested it yet.. its only 17 ounces of water wihch kinda blows.. but it might keep it cooler..
If you dont have one of these bottles i'd recommend at least 1.. and max it out with ice and ice cold water and it should last you at least 1 to 2 hours on a moderately hot day.. I have not tested these in the INTENSE heat since it never gets that hot here in washington, and i think the summer's starting to die off now.. but maybe next year
(best feature, the bottle doesnt sweat, so no more MUD on your hands when you go to pick it up!). Great nozzles, easy close easy open (with your teeth too! very great!) and good dispertion of water.. It works best if you squeese small amounts rapidly for me