Rex, Rex Motorcycles, Rex-Acme, was a motorcycle company which began in Birmingham, England in 1900. Rex soon merged with a Coventry bicycle maker named Allard and then later in 1922 the company merged with Coventry's 'Acme' motorcycle company forming 'Rex Acme'. The company existed until 1933, and, in its heyday, was considered one of the greatest names in the British motorcycle industry.
Originally, Rex Motorcycles was founded in Birmingham by brothers William and Harold Williamson in 1899, merged with Allard, a Coventry bicycle maker, in 1902, the name remaining Rex. In 1904 they began making motorcycles. The founders were fired by the company in 1911. In 1919 Coventry Acme was taken over, and in 1922 the two companies were amalgamated to form Rex-Acme. Wal Handley then raced Rex-Acme motorcycles, making them famous, and even became a company director, but left in 1928 to ride different machinery. Handley rode Blackburne 173 cc singles, and, in 1926, ohv 498 cc V twins. The name began to fade, and in 1932 was taken over by side-car manufacturers, Mills-Fullford, who ceased manufacture of Rex-Acme motorcycles in 1933. Other famous motorcycle racers that rode Rex-Acme motorcycles were H. G. Tyrell Smith, Arthur Taylor, Charles Needham, Hans Hasenauer, Felice Bonetto, Karl Machu and Otto Cecconi.
Rex (1903 - 1922)
Around 1903 Rex produced motorcycles with engines above and driving, the front wheel. (the Werner engine position). The engines were Rex’s own, and included singles and V twins. In 1904 there was a 372 cc model which had the silencer cast with the cylinder in one piece. In 1905 the side valve Rex model was rated at 3.25 hp. When they stopped producing these, they used Blackburne engines of 532 cc and 896 cc with Roc patent gear hubs. When the company fired the founders in 1911, George Hemingway had in house engines made again, but models with other engines were still built. Rex made their first telescopic forks in 1906, used rotary-valve engines, and in 1908 were the first to put a downward angle on the top tube, lowering the riding position. In 1914 there was a 349 cc two stroke and 940 cc V twins.
After the First World War, the first bike, a 550 cc sv single, was soon dropped in favour of new Blackburne engined machines. These had a longer wheelbase sidecar version available. The singles now had 499 cc, the V twins 998 cc.
Rex Acme (1922 - 1933)
In the years that followed Rex-Acme motorcycles used engines from 173 cc to 746 cc. There were sv and ohv Blackburne engines, sv JAP engines and also a sleeve valve 348 cc Barr & Stroud. In 1928 there was a 346 cc ohv MAG engined model.
The 1929 Rex-Acme range consisted of 346 cc ohv models with two JAP versions, one with 74 mm bore x 80 mm stroke and the other with 70 mm bore x 90 mm stroke; also available as double port engines; 746 cc JAP engined V twin; 496 cc sv singles with JAP or Blackburne engines; 300 cc sv singles with cheaper frames and JAP or Blackburne engines and also similar 346 cc versions., the Speed King with 346 cc Blackburne ohv engines in two versions; and also two versions of a 496 cc Blackburne engined ohv single. There was also a 172 cc Villiers engined super sports model.
- "British Motorcycle Charitable Trust". Retrieved 5 November 2011.
-  IanChadwick.com Rex (Retrieved December 10 2006)
-  BMCT.org The Machines (Retrieved December 10 2006)
- Title: The Illustrated Encyclopedia of Motorcycles, Editor: Erwin Tragatsch, Publisher: New Burlington Books, Copyright: 1979 Quarto Publishing, Edition: 1988 Revised, page 260, ISBN 0-906286-07-7.