Leonardo da Vinci designed an early ball bearing using wooden balls between two rings.
Around 1498, Leonardo sketched a bearing in which balls moved between two concentric rings. The rolling elements reduced sliding friction and helped keep the rings from rubbing directly against one another. His design is one of the earliest known attempts to use the basic arrangement of a modern ball bearing.
Leonardo's bearing was a concept for reducing friction in machines, not a modern sealed bearing made from precision steel. Wooden balls and Renaissance manufacturing limits would have restricted durability and accuracy. The idea is also separate from a wheel itself: a bearing supports rotation around an axle, while the wheel provides the rolling structure or transfers motion.