Get the NavParent app — Google Play · App Store NavParent Grow — for ages 3 to 12 Nine tracks on confidence, manners, money and gratitude. A short lesson for you, then something to do together. Start free → NavParent Verdict Do not buy by age. The same 16-inch cycle is sold to 4-year-olds and 8-year-olds depending on which listing you open. Measure the inside of your child's leg instead, and make sure both feet go flat on the ground when they sit on the seat. That takes t