Ready for a bike ride? Aim for 9–12 months when neck muscles support a helmet....

https://gregorywads092.lowescouponn.com/can-i-use-a-child-bike-seat-on-a-mountain-bike-a-pro-s-guide-to-trail-ready-parenting

Ready for a bike ride? Aim for 9–12 months when neck muscles support a helmet. If your baby sits upright unsupported, front or rear rack-mounted seats work great. Before that milestone, use a trailer with an infant insert. Prioritize neck stability!