Our Solution
 
Picking up from the problem of finding a cup that remains horizontal at all times, we can up with a solution of a drink holder mounted on gimbals. With a cup on gimbals, whether on a bike or in a car that turns and jumps, your drink will always stay inside its container. A gimbal is a pivoted support that allows the rotation of an object about a single axis. A set of two gimbals, one mounted on the other with pivot axes orthogonal, may be used to allow an object mounted on the innermost gimbal to remain vertical regardless of the motion of its support. Below : A solid works sketch of a gimbal