Harley-Davidson Knucklehead Chopper: A two-wheeled icon


Born to be wild, the Chopper, a platform for artistic and mechanical expression, with extravagant use of chrome, wildly extended springer forks and brilliant paintwork on the tank, is now a piece of American history.

Installation view of ‘The Motorcycle: Design, Art, Desire’, Gallery of Modern Art (GOMA), Brisbane highlighting the Harley-Davidson Knucklehead Chopper on display / Photograph: Natasha Harth © QAGOMA

Harley-Davidson Knucklehead Chopper C.1973 (Engine: 1941)

The chopper is a type of customised motorcycle that emerged in California in the late 1950s. It is perhaps the most extreme of all custom motorcycle styles, often using radically modified steering angles and lengthened forks for a stretched-out appearance. They can be built from an original motorcycle which is modified (‘chopped’), or from scratch. Other characteristic features of choppers include: hardtail frames (frames without rear suspension); very tall ‘ape hanger’ or very short ‘drag’ handlebars; lengthened or stretched frames; and larger than stock front wheels. The ‘sissy bar’ — a set of tubes that connect the rear fender with the frame — is also a signature feature of many choppers.


RELATED: Read more about the bikes in ‘THE MOTORCYCLE’ exhibition

This Harley-Davidson chopper is built around a 1941 Knucklehead engine, a perennial favourite for chopper builders. At the top of the cylinders knobby covers are held in place by two large nuts — these are the rocker covers, and their knuckly contours gave rise to the nickname, which became popular among chopper builders in the 1960s and 1970s. The rest is the builder’s own imagination, played out in the chrome details, the forks, the high handlebars and pinstripe paint.

‘Where did you get the motorcycle?’
‘It’s not a motorcycle, baby, it’s a Chopper.’
Pulp Fiction 1994

Peter Fonda riding a Captain America chopper / Photograph: Brian Snelson / Image Courtesy: Wikimedia Commons

Custom Motorcycles

It was not until Honda revolutionised industrial production in the 1960s that motorcycles started to be built to exacting technical standards. Prior to that, in Britain, Europe and the United States, new machines might only be a ride away from having a part break or fall off — commonly referred to as a ‘shakedown ride’. Customisation was born from this need to repair and maintain new motorcycles, but went further, to make motorcycles better, faster, louder, brighter and different to factory-produced models.

So-called ‘cut-downs’ and ‘bob-jobs’, aimed at reducing a motorcycle’s weight, were the first customs to emerge in the United States in the 1920s and 1930s. After World War Two, the terminology changed: custom bikes were now ‘choppers’, with exuberant paintwork, indulgent chrome, wildly extended front forks and high, ‘ape-hanger’ handlebars, famously featured in Dennis Hopper’s 1969 film Easy Rider which gave central roles to two Harley-Davidson choppers, thereby enshrining the design in popular culture.

Harley-Davidson Knucklehead Chopper c.1973 (engine: 1941) / Private Collection / Photographs: Andrea Beavis


Country: USA
53 hp

Engine: 1207 cc OHV 45° V-twin
Production: Custom

Interesting facts

  • ‘Knucklehead’ is a word used by enthusiasts to refer to a Harley-Davidson motorcycle engine, named after the distinct shape of the rocker box covering for an overhead valve that resembles two knuckles on a clenched fist.
  • The spark plugs of a knucklehead fire at uneven intervals, contributing to its unique cadence, described as sounding like ‘potato, potato, potato’; ‘pop, pop, pause’; or the ‘snap, crackle, pop’ of the motor running.
  • On 27 January 1973 President Richard Nixon signed the Paris Peace Accords, ending direct US involvement in the Vietnam War. On their return, Vietnam veterans turned to the camaraderie, excitement, danger, speed and escapism of motorcycles and biker clubs. The huge success of the 1969 film Easy Rider instantly popularised the chopper around the world, and drastically increased demand for them. What had been a subculture known to a relatively small group of enthusiasts in a few regions of the US became a global phenomenon.

Film: Easy Rider (1969)

This now-classic road movie turned the B-movie youthquake into an international art cinema. Easy Rider 1969 tells the story of Captain America and Billy the Kid as they go looking for America. As they motor along to their inevitably tragic end, our heroes do drugs, have their rights violated, meet some interestingly allegorical groups of folks, and find themselves framed by László Kovács’s gorgeous cinematography.

Production still from Easy Rider 1969 / Director: Dennis Hopper / Image courtesy: Park Circus

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‘The Motorcycle’ exhibition was in Brisbane’s Gallery of Modern Art (GOMA) from 28 November 2020 until 26 April 2021.

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