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.
Maine requires a bicycle helmet for any rider under the age of 16. The same rule extends to children carried as passengers in a child seat or trailer. 29-A M.R.S. § 2323 requires every operator and passenger under 16 to wear a properly fitted helmet that meets ASTM, Snell, or ANSI standards. A first violation results in a warning; subsequent violations carry a fine of up to $25, which a court may waive on proof of helmet purchase. See 29-A M.R.S. § 2323 (Bicycle and roller-ski helmets).
If you're 16 or older, Maine doesn't require you to wear a helmet by state law. Riders under 16 (and any child carried as a passenger) must wear a helmet that meets the ASTM, Snell, or ANSI (a CPSC-certified helmet meets these specifications) 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.