Thats not a tough one. With a straw (and I got rid or the rigid one after the first ride) I can lift the tube and drink without getting out of my aero position even for a second. Just a little turn of the wrist. No other fluid replenishment solution allows a lower aero penalty, especailly since most racing orgs don't let you use IVs anymore (yeah someone tried it in a race).
Styrrell
Styrrell
Styrrell
Styrrell