Thanks for all of the information! My bike doesn't have room for anything on the seat post (would have to lose my seat bag)...really my only options are the Camelbak, a bottle in the cage, and a smaller one in my jersey pocket if needed. This works for me though
My OTHER bike, soon to come out of the shop, has three water cages - though I will likely still use the 'Bac as it works for me....