What is moment of inertia (or translational moment of inertia )?

An object’s moment of inertia determines how much it resists rotational motion. In this simulation, four objects are placed on a ramp and left to roll without slipping. Starting from rest, each will experience an angular acceleration based on their moment of inertia.

Four objects with identical masses and radii racing down a plane while rolling without slipping. From back to front: spherical shell (red), solid sphere (orange), cylindrical ring (green) and solid cylinder (blue). The time for each object to reach the finishing line depends on their moment of inertia.  Lucas V. Barbosa For even more bicycle specific information on MOI, look at this concise blog post by our good friend Ric Hjertberg at Wheelfanatyk.