Children who are old enough (12 months to 4 years) to sit well unsupported and whose necks are strong enough to support a lightweight helmet may be carried in a child-trailer or rear-mounted seat. A rear-mounted bicycle passenger seat must Be securely attached over the rear wheel

Most bikes are compatible with at least one type of child seat. For example, most mountain, road, and cruiser bikes will work with a rear-mounted child seat. On the other hand, a front-mounted seat typically won’t work with road or full-suspension mountain bikes. Some bikes are simply better suited for child seats.