This guide is for general information only and is not legal advice. Laws change — verify current rules with your state DOT or a licensed attorney before relying on this for any legal matter. Read full disclaimer.
New Mexico requires a bicycle helmet for every rider under 18 — in practice, every rider except adults aged 18 and over. The same rule extends to children carried as passengers in a child seat or trailer. NMSA § 66-3-707 requires every rider and passenger under 18 to wear a properly fitted, securely fastened helmet that meets CPSC, ANSI, Snell, or ASTM standards on any public road, sidewalk, bicycle path, or trail. The penalty is a civil infraction; the first offense is dismissed on proof of helmet purchase, with fines of up to $10 thereafter. See NMSA § 66-3-707 (Bicycle and recreational-vehicle helmets).
If you're 18 or older, New Mexico doesn't require you to wear a helmet by state law. Riders under 18 (and any child carried as a passenger) must wear a helmet that meets the CPSC, ANSI, Snell, or ASTM (a CPSC-certified helmet meets all four) standard.
Cities can be stricter than the state floor, and bike-share systems often require helmets regardless of age. If you're renting or commuting in a major city, confirm the local rule before you ride.