The roller chain is a fundamental component in mechanical power transmission, especially in systems requiring strength, durability, and efficiency. Its origins trace back to Leonardo da Vinci, who sketched early chain concepts in the 15th century. However, the modern roller chain was first developed and patented in the late 19th century during the rise of industrial manufacturing.In 1880, the design was refined and standardized for use in bicycles, and later became a key transmission component in motorcycles, agricultural machines, and industrial conveyors. The invention of the bushing and roller design allowed for smoother movement, reduced wear, and better load distribution compared to earlier chain types. A roller chain consists of inner and outer links, bushings, and rollers that mesh with sprockets to transmit rotary motion. It is known for its mechanical efficiency, reliability, and long service life. The roller chain is a time-tested, highly efficient component that remains essential in modern mechanical systems. From industrial conveyors to motorcycles, its ability to deliver reliable power transmission under varying loads and speeds has made it a global standard for over a century.