The brackets are of many sizes and are easy to overlap, plus all bikes have different matching sizes (even if they have the same wheel size), so please take your child to your local bike shop for some fun test rides! Pro tip: If your child is over 12 years old or taller than 4’ 8″, you can start considering buying an adult bicycle.
The following are our recommended bicycle sizes for children of different ages:

Bicycle suitable for children 2-3 years old
Height: 3’ 0”-3’ 3”
Inner seam: 15″-18″
Wheel/bicycle size: 12” (balance bike or auxiliary wheel bike)

Bicycle suitable for children 4-6 years old
Height: 3’ 5”-4’ 0”
Inner seam: 16″-22″
Wheel/bike size: 16″

Bicycle suitable for children aged 5-8
Height: 3’ 9”-4’ 6”
Inner seam: 19″-25″
Wheel/bike size: 20″

Bicycle suitable for children aged 8-11
Height: 4’ 1”-4’ 11”
Inner seam: 23″-28″
Wheel/bike size: 24″

Bicycle suitable for children aged 10-12
Height: Up to 4’8″
Inner seam length: maximum 25″
Wheel/bike size: 26″

Buy adult bicycles for older kids
Many older and taller children can ride the smallest adult bicycles. When you look at adult bicycles, remember that they are sold by frame size, not by wheel size!