This document describes aerodynamic water bottles for bicycles. In one aspect, an aerodynamic water bottle includes a curved front portion that includes an attachment mechanism. The attachment mechanism includes a first fastening member and a second fastening member opposite the first fastening member. At least one of the first fastening member or the second fastening member is configured to pivot away from the other of the first fastening member or the second fastening member to place the attachment mechanism in an open position. When in a closed position, the attachment mechanism includes an opening for a seat post of a bicycle to extend through. The opening is formed by a first curved surface of the first fastening member and a second curved surface of the second fastening member. A back portion includes a hollow interior vessel for storing a liquid, the back portion further comprising a spout.