The youngest age at which someone can learn to ride a bike varies depending on the child's physical and cognitive development. Generally, children start learning to ride a bike with training wheels around the age of 3 or 4. By the age of 5 or 6, many children can begin riding a bike without training wheels. However, it's important to note that every child is different, and some may learn earlier or later than others.
As for learning to ride a motorcycle, the minimum age requirements differ across countries and jurisdictions. In many places, the minimum age to legally ride a motorcycle on public roads is around 16 or 17 years old. However, learning to ride a motorcycle at a young age is not recommended due to the physical and cognitive demands of operating a motorized vehicle. It's important to follow the legal age requirements and ensure that individuals have the necessary maturity, coordination, and understanding of road safety before learning to ride a motorcycle.
On the other end of the spectrum, there is no upper age limit for learning how to ride a bike or motorcycle. As long as a person is physically capable and willing to learn, they can start at any age. In fact, many adults learn to ride bikes or motorcycles later in life for various reasons, such as recreational purposes or transportation needs.