Sinclair C5

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Sinclair C5

The Sinclair Research C5 is a battery electric vehicle invented by Sir Clive Sinclair and launched by Sinclair Vehicles Ltd in the United Kingdom on 10 January 1985. The vehicle is a battery-assisted tricycle steered by a handlebar beneath the driver's knees. Powered operation is possible making it unnecessary for the driver to pedal. Its top speed of 15 miles per hour (24 km/h), is the fastest allowed in the UK without a driving licence. It is powered by a 200W or 250W motor. It sold for £399 plus £29 for delivery.

It became an object of media and popular ridicule during the 1980s in Britain and was a commercial disaster, selling only around 17,000 units. Sinclair claimed it remained "the best selling electric vehicle" as recently as 2010,[1] although it was overtaken in 2011 when the Nissan Leaf had sold over 20,000 units.[2]


Sir Clive Sinclair started to think about electric vehicles as a teenager, and it was an idea he toyed with for decades. In the early 1970s Sinclair Radionics was working on the project. Sinclair had Chris Curry work on the electric motor. However, the company focus shifted to calculators and no further work was done on vehicles until the late 1970s. Development began again in 1979 and progressed erratically until, in 1983, it became apparent new legislation would alter the market and make it possible to sell a vehicle closely resembling development efforts.

As time went on, the Sinclair Research C5 development cost gradually increased. In March 1983, Sinclair sold some of his shares in Sinclair Research Ltd and raised £12 million to finance vehicle development. In May a new company, Sinclair Vehicles Ltd, was formed out of Sinclair Research and a development contract entered with Lotus to take the C5 design to production. At the same time, the Hoover Company at Merthyr Tydfil contracted to manufacture the C5. This, together with the fact that the motors were made by Polymotor in Italy, started the urban myth that the C5 was powered by a washing machine motor.[3] In 1984, Sinclair Vehicles Ltd set up head office at the University of Warwick Science Park.


Despite promotion involving former Formula One racing driver Stirling Moss, the reaction upon its release was that the C5 was impractical in the British climate meaning it was only comfortably usable in northern England in the spring and summer, and possibly dangerous on busy roads.

On 13 August 1985, the Hoover Company announced the end of production. Only around 17,000 C5s had been sold.[1] Sinclair Vehicles was put into receivership on 12 October 1985.

Design problems[edit]

The C5 suffered from problems: cold weather shortened battery life, the driver was exposed to the weather, and because it was low to the ground, doubts were raised about its safety in traffic. The problems were addressed with a second battery, side screens for bad weather and a reflector on tall poles - all available as extras from the launch.[4] The problems were expressed in a cartoon showing a C5 and a juggernaut approaching each other at a blind corner, the C5 being occupied by lemmings.[citation needed] Users of recumbent tricycles and a study by the Department of Transport suggested visibility fears were largely unfounded, but the weight, lack of seat-to-pedal adjustment, lack of gears, short pedal cranks, and that the motor overheated on long hills were serious problems;[5] indeed the motor was essentially useless for climbing hills, with even mild gradients necessitating significant pedal assistance.

Modified C5s[edit]

Sinclair C5 displayed in Glasgow's Riverside Museum

A heavily modified C5 reached a top speed of 150 miles per hour (240 km/h) and accelerated from 0 to 60 mph in 5 seconds taking the speed record for an electric vehicle.[6] The C5 also became the world's first electric stunt vehicle when it was driven through a 70 ft tunnel of fire.[7] A "turbo conversion" converting the C5 to 24 volts and boosting the speed to 27–30 miles per hour (43–48 km/h) is available.[8]

During the Swiss Tour de Sol in the early 1990s, several C5s were solarised and modified to provide more range and speed. Plans were made available for these conversions, required to use the C5 legally in Switzerland.

Sinclair C5s have also been converted to jet engine power.[9]

In 2006, another Sinclair C5 was fitted with a hybrid rocket engine for an episode of Sky TV's Brainiac science show. After evaluating the performance of three different fast foods as rocket fuels (combined with nitrous oxide), the winning fuel was used to propel the C5 in a drag race with an electric scooter.[10]

Sinclair X-1[edit]

In November 2010, Sinclair told The Guardian he was working on a new prototype that should be launched within a year. "Technology has moved on quite a bit, there are new batteries available and I just rethought the thing. The C5 was OK, but I think we can do a better job now." He said the prototype was called the X-1.[11][12] The X-1 was meant to launch in July 2011 at a price of £595.[13] but so far there has been no confirmation of any release.

See also[edit]


  1. ^ a b "Sinclair Research - About Us". Sinclair Research Ltd. Retrieved 2011-07-18. 
  2. ^ Damon Lavrinc (2011-11-30). "Nissan sells 20,000 Leafs worldwide, 10,000 in U.S. by end of the year". AutoblogGreen. Retrieved 2011-11-30. 
  3. ^ Sinclair C5 Enthusiasts website. "The C5 uses a washing machine motor". Retrieved 2006-09-16. 
  4. ^ Sinclair C5 Enthusiasts website. "C5 Accessory Catalogue". Retrieved 2006-09-16. 
  5. ^ P.J. Milner and P. Newman. "The Sinclair C5 Electric Vehicle". Retrieved 2006-09-16. 
  6. ^ Sinclair Research. "Film Hire, The Sinclair C5 Test Car". Retrieved 2006-09-16. [dead link]
  7. ^ Sinclair Research. "Sinclair C5 Background Information". Retrieved 2006-09-16. [dead link]
  8. ^ Sinclair Research. "Sinclair C5 Modifications". Retrieved 2006-09-16. [dead link]
  9. ^ Pleiadean Media -
  10. ^ Celestial Mechanics, The Brainiac project
  11. ^ Simon Hattenstone, The Guardian (2010-11-13). "Whose bright idea was that?". London. Retrieved 2010-11-13. 
  12. ^ Sinclair Research X-1
  13. ^ Sinclair X-1 Official Web Site


  • Adamson, Ian; Kennedy, Richard (1986). Sinclair and the "Sunrise" Technology. London: Penguin Books. 224 pp. ISBN 0-14-008774-5.
  • Dale, Rodney (1985). The Sinclair Story. London: Duckworth. 184 pp. ISBN 0-7156-1901-2.

External links[edit]