Damn near everything I've seen online for moments of inertia, as a reference, only includes moments of inertia that have the axis of rotation either through one end of the object, or through the center of mass. I'm trying to figure out how to find the moment of inertia for an object that is rotating about an axis that is outside of the body of rotation, like say, one that is attached to an axle by a massless, infinitely thin and rigid rod. What's the easiest way to calculate this for, say, a uniform cylinder or sphere where the center of mass is some distance away from the axis of rotation?