With the instant success of the Triumph vertical twin design, other manufacturers rushed their own versions into production. The Ariel Twin copied Triumph, with identical bore and stroke. This motor weighed only one pound heavier than their 500cc single despite the use of cast iron for the cylinder and head. For 1953 the motor was redesigned with an all alloy head and barrel. 1954 saw major changes: a "New" motor which was a BSA A10 disguised as an Ariel!