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The extended frame of an Xtracycle allows a cyclist to carry large loads.

An Xtracycle or Xtrabike is a variety of load-carrying bicycle. An Xtracycle may be constructed by modifying an existing bicycle with an extension called a Free Radical,[1] or by custom-building an extended-tail bicycle frame. Xtracycles are promoted as a way to achieve a bicycle-centric transportation lifestyle.

Web forums and blogs often use the shorthand Xtra for Xtracycle, or simply X to refer to either the Free Radical extension or the entire extended bicycle. It is also sometimes described as a longtail or a longbike.

Differences from other load-carrying bicycles[]

While the Xtracycle is based on a standard hardtail diamond frame with 26-inch or 622 mm (700c) wheels, the Xtracycle differs from other load-carrying bicycles in that it does not employ a handlebar basket, panniers, or a bicycle trailer. Baskets are easy to attach and allow stowing of cargo in plain view. Panniers are often watertight or water resistant, and can be easily removed from their racks and carried as luggage. Trailers come in many shapes, sizes, designs, and qualities, and allow a bicycle to pull a significant amount of cargo. In contrast, an Xtracycle employs an extended frame on which large containers are suspended, allowing for more stowage capacity on the bicycle itself. Xtracycles are also called "sport utility bicycles" for their ability to carry larger loads than a normal bicycles having baskets or panniers.

History and Spinoffs[]

The Free Radical was conceived by Ross Evans at Stanford University and developed during his work in the mid-1990s managing a "Bikes Not Bombs" project in Nicaragua, where having a bicycle enhances a person's employment opportunties. In 1998 Evans and his friend Kipchoge Spencer created Xtracycle Inc to manufacture and market the invention, as well as a nonprofit organization, Worldbike, devoted to encourage a bicycle-centric lifestyle and culture.[2]

Despite the fact that the Free Radical qualifies as an aftermarket bike accessory, its growing acceptance has sparked an Xtracycle aftermarket not formally connected with Xtracycle Inc: varieties of specialized kickstands, electric-assist motors, and even bike-mounted blenders have come to market, even though each requires the prior purchase of a Free Radical to function properly.

Big Dummy[]

Xtracycle Inc has also entered into negotiations with various bicycle manufacturers to build purpose-built extended bicycles compatible with their accessories. The first to actually produce and market an integrated Xtracycle frameset known as the Big Dummy, was Surly Bikes, presently available in bicycle retail outlets.[3]. XInc hopes to form similar covenants with manufacturers in all price ranges to the end of making the Xtracycle less of a niche product and more mainstream. XInc is also working on Free Radical attachments sized for children's and youths' bicycles on the theory of "catch 'em young and train 'em right."

Other applications for the Free Radical have included linking two Xtracycles to support a mobile stage for use in parades and street fairs, and a computerized chalkpowder-printer device to be mounted on an Xtracycle that leaves dot-matrix trail of messages on the street.[4]


In 2009 the Radish was launched by Xtracycle. It is a full frameset like Big Dummy with the same Free Radical frame.

See also[]


  1. Xtracycle Inc manufactures the Free Radical kit and associated accessories.
  2. Retherford, Brittany. One step at a time: Duo's film, innovations geared to a healthier world. The Union, (2006-01-12).
  3. Template:Cite web
  4. Kinberg, Joshua. Bikes Against Bush "Maiden Voyage" Video, (2004-08-01).

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