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

https://www.wall-bookmarkings.win/most-babies-are-ready-for-a-bike-seat-around-12-months-your-child-needs-to

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!