When your child reaches about 4'9" in height they're tall enough for an adult bike. These bikes will have 26", 27.5" or 29" wheels. Most kids this age want a bike that is versatile enough to ride on different surfaces and entry-level mountain bikes fit this bill. These bikes come sized from XXS frames for the shorter riders, to XXL for the tallest riders. Visit the store and we are happy to measure your child up for the appropriate size.