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Simplex Manufacturing Corporation

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Simplex Manufacturing Corporation

Simplex Servi-Cycle
Manufacturer Simplex Manufacturing Corporation
Also called Wizard[1]
Production 1935-1960
Assembly New Orleans
Class Lightweight standard
Engine Single cylinder two-stroke 7.9 cu. in. (130 cc)
Bore / stroke 2 x 2.53 inch
Compression ratio 6.5:1
Power 4 hp at 5000 rpm
Ignition type magneto (by Simplex) and dual spark plugs
Transmission 1935-1941: direct drive, no clutch
1941-1953: direct drive with clutch
1953-1960: variable-speed automatic
Frame type double-loop tube frame
Suspension Front: short rocker arms and two coil springs on top of suspension tubes
Rear: None, rigid
Brakes Front: None
Rear: 5 inch drum brake operated by pedal on right side.
Tires 26 x 2.50
Wheelbase 47 inch
Weight 135 pounds (dry)
Fuel capacity 2.5 gallons

Simplex Manufacturing Corporation was an American manufacturer that made motorcycles from 1935 to 1975. Between 1935 and 1960, Simplex made variations of the Simplex Servi-Cycle including the 1953–1960 Simplex Automatic. Simplex was the only motorcycle manufacturer located in the Deep South.


Simplex was founded by Paul Treen (father of United States Congressman and Louisiana Governor David Conner Treen) in New Orleans, Louisiana in the late 1920s with an initial investment of $25.[2] Treen had been a dealer in Harley-Davidson motorcycles and had pitched them the idea of making a lightweight motorcycle for young riders. When Harley-Davidson rejected the idea, Treen decided to enter the market himself and designed his Servi-Cycle.[3] The Simplex Servi-Cycle was introduced in 1935.[3]

Although Simplex Manufacturing Corporation produced motorcycles for over 20 years, the last Simplex Automatics looked almost the same as the company's original 1935 Simplex Servi-Cycle motorcycle. Paul Treen would often visit the factory's tool shop and work with the engineers on new ideas himself, result in continuous improvements to Simplex products instead of annual new model introductions.[2][4]

Western Auto sold Simplex motorcycles under the Wizard brand in the mid-1950s.[1]

Simplex's minimalist philosophy was maintained throughout the company's history, whose designs changed little after 1935. By the 1950s Simplex's designs were primitive, leading to the end of Servi-Cycle and Automatic production in 1960.[4][5] Simplex continued to make minibikes and karts using proprietary small engines[5][6] until 1975, when Simplex went out of business.[5] Treen had sold the company three years earlier, in 1972.[7] Simplex was the only motorcycle manufacturer located in the American South.[6]

A 1935 Simplex Servi-Cycle motorcycle is currently on display in the Smithsonian Institution's America on the Move exhibit.[8]


The two-stroke engine had a rotary valve[5][8] and an "overhung" crankshaft with only one main bearing.[5][9] A kick-starter was added by 1953.[10]

The Servi-Cycle was claimed to have a fuel economy of 100 mpg-US (120 mpg-imp; 2.4 L/100 km).[11]

The Servi-Cycle used a magneto of Simplex's own design, providing 6 volt electricity for the dual ignition and for the headlight, taillight and stoplight. The engine had dual spark plugs in its cylinder head.[7]


The original Servi-Cycle design had the engine drive the rear wheel by belt, with no transmission or clutch, requiring the engine to be shut off while the cycle is at rest.[8] In 1941, a pedal-operated clutch was added.[10]

In April 1953, Simplex added a variable speed automatic transmission[4] with centrifugal shoe-type clutch and belt-type automatic transmission. The ratio was changed by expanding and contracting the drive pulley, with a low ratio of approximately 18:1 and a high ratio of approximately 7:1. The transmission was belt-driven and drove the real wheel by belt, with automatic belt tensioning by jockey pulley.[7]

Simplex Automatic scooter

In 1956, Simplex began manufacturing a scooter based on the Simplex Automatic drivetrain. The scooter was not made in large numbers and was discontinued in 1960 along with the Servi-Cycle.[6]


  1. ^ a b Hatfield, Jerry (2006-02-08). "W". Standard Catalog of American Motorcycles 1898-1981: The Only Book to Fully Chronicle Every Bike Ever Buil. Iola, WI USA: Krause Publications. p. 446.  
  2. ^ a b Mitchel, Doug (1995). "1956 Simplex Automatic". Motorcycle Classics. Lincolnwood, IL USA: Publications International. pp. 82 83.  
  3. ^ a b Kolb, Carolyn (September 2010). "SIMPLY SIMPLEX – Affordable wheels for a generation". New Orleans Magazine (Magazine article). Renaissance Publishing. Archived from the original on 2012-11-04. Retrieved 2012-11-04. But, Harley-Davidson didn't take up the idea of adding smaller machines to its line, so Paul Treen decided to build and sell the small cycles himself. 
  4. ^ a b c Wood, Bill, ed. (July 1994). "Classics: 1957 Simplex Automatic". American Motorcyclist (Westerville, OH USA:  
  5. ^ a b c d e Wilson, Hugo (1995). "The Directory of Motorcycles". The Encyclopedia of the Motorcycle. London: Dorling Kindersley. p. 275.  
  6. ^ a b c Wilson, Hugo (1995). "The A-Z of Motorcycles". The Encyclopedia of the Motorcycle. London: Dorling Kindersley. p. 169.  
  7. ^ a b c Wollard, Gary (1956). "Motorbiking, the Simplex Way". Compressed Air. 
  8. ^ a b c "Simplex Servi-Cycle". America on the Move – Smithsonian National Museum of American History. Retrieved 2012-11-04. The single-cylinder, 2-cycle, 2-horsepower engine is air cooled and equipped with a rotary valve. 
  9. ^ Hunn, Peter (2005-06-13). "Chapter 2: Short Profiles of Manufacturers". The Small-Engine Handbook. Motorbooks Workshop. St. Paul, MN USA: MBI Publishing. p. 50.  
  10. ^ a b "c. 1946 Simplex Servi-Cycle". London, UK:  
  11. ^ How Stuff Works: 1956 Simplex Automatic

External links

  • 1956 Simplex AutomaticHowStuffWorks
  • article from American Motorcyclist, July 19941957 Simplex Automatic
  • article as printed in Cycle magazine copyright February 1956You Can Ride the Simplex Automatic
  • article from Walneck's Classic Cycle Trader, October 1995Motorbiking the Simplex Way
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