I read this in another forum...takes some getting used to but it does help!

Reach down and grab your bottle with the palm of your hand ensuring that the pinkie finger is on top (Look down at your right hand...looking at the back of the hand turn your hand so that your fingers are pointing to your left hand) this is how you want to grab the bottle, as you are bringing the bottle to your mouth, twist your hand around so that your can drink. This gives you a better angle of bottle to mouth and helps your drink more water with less effort. I sat on the couch with a water bottle for a while practiceing this move and it really is easier to drink this way on the bike.

It'll make sense after you try it a couple of times! Good Luck!!