Wait until your child is one. They must sit independently and support their...

https://mega-wiki.win/index.php/How_Do_I_Keep_My_Toddler_from_Kicking_My_Back_While_I_Pedal%3F

Wait until your child is one. They must sit independently and support their head while wearing a helmet. Trailers provide the safest environment for infants, while front or rear seats suit active toddlers. Keep your first rides short and smooth.