iron horse

plural iron horses

1. transportA railroad steam locomotive.
2. informalA motorcycle.

   Synonyms: steel horse

3. datedhumorousA velocipede; a bicycle.

   Run beside your iron horse, leading it, as it were, with your hand, so as to familiarize yourself with its movements : this will be an affair of a few minutes merely.

   1868 December 26, “Velocipedes”, in Supplement to the Courant, Hartford

   1 more example

   The rapid extension of the masses of bricks and mortar which constitute our enormous cities, makes it difficult to reach green fields or breathe fresh air by the use of the means of locomotion given to us by nature, but the happy possessor of a tricycle or bicycle, independent of distance, spins off on his iron horse, soon to reach green fields and pastures new.

   1882 March 1, “The "London Medical Record" on bicycling and tricycling”, in London Bicycle Club Gazette

1. A census-designated place in Plumas County, California, United States.