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An Eccentric-hub scooter is a two-wheeled human powered vehicle with an off-centered hub on the large rear wheel and is powered by the rider making a bouncing motion on the platform.
An Ingo-bike is a vehicle similar to a kick scooter, with a large rear wheel, mounted off-centre. The vehicle is propelled by the user bouncing up and down or rocking backwards and forwards on the platform to drive the rear wheel around the eccentric hub. One early inventor described the vehicle as a 'galloping scooter' and the rider's motion does resemble a horse-rider's motion. Although the motion produced is impact-free, it is reportedly less efficient than a conventional bicycle and will not propel the vehicle uphill.
Exercycle / Ingo-Bike
Although several patents for eccentric-hub cycles exist from 1928   , the most popular incarnation was made from 1934 by brothers Phillip and Prescott Huyssen and called the "Exercycle"  . It was produced by the Ingersoll Steel & Disc Co. (a division of Borg-Warner Corp.), from 1934–1937, under the name "Ingo-bike". A large number of publicity events and promotions popularised the bike and a group of Ingo-bikers in the late 1930s traveled from Chicago to Miami in 30 days. Production ceased when the factory re-tooled to begin producing armaments prior to the Second World War. Phillip Huyssen continued designing variations until at least the 1970s.  In the Three Stooges movie Yes, We Have No Bonanza  , Curly rides up to a saloon bar on an Ingo-Bike. 
Apparently re-introduced as a children's scooter in the 1960s with the name "kangaroo scooter", kangaroo scooters were built in Taiwan for a company based in Concord,California. They had the eccentric rear wheel and a front caliper brake,chrome fenders and a kickstand.
Another device also called the Kangaroo Scooter has been designed and sold by Ron and Johnny Knox's company, Knoxcooter Inc., of Weyburn, Canada since around 2004. This variant includes a one-sided rear wheel support, disk brakes and uniquely a clutched rear hub; which allows the user to coast for periods without bouncing up and down. Contrary to popular belief, the Eco-Fav (Frequency Accelerated Velocipede) scooter is efficient enough to ride uphill. Many users prefer to ride it on an incline to increase their workout resistance.  
A similar concept is the 'Bounce-Bike' which has an eccentric front wheel and a small rear wheel.
Variants have been produced since the 1990s and called "whymcycle", by inventor/substitute teacher Peter Wagner. The term 'Whymcycle' Wagner coined by taking the common word 'whimsical', which means imaginative, fanciful or eccentric; socially eccentric, that is. Also, the Ingo-style bike he makes has an eccentric rear axle for propulsion, as well as being a rather fanciful mode of transport. To complete the trifecta of this bike's nomenclatural origins, Wagner's middle name is William, which he abbreviates as 'Wm.'. Hence the bikes he makes are:
- Wm.'s cycles
- whimsical - imaginative,
- whimsical - eccentrically powered and socially off-center to boot.
Twenty five years of production has resulted in 125 'Whymsies', thus far. The term has come to apply to all of the styles of creative cycles he makes, from handcycles for riders with leg disabilities, to assorted cycles: front wheel drive, recumbent bikes and trikes, quadracycles, tall bikes, high wheelers- big and small, as well as tandems and sociable trikes of various stripes. Kinetic Sculptures, that is, all-terrain amphibious human -powered machines, which have been built and raced on the West Coast since 1969, are also some of the machines Wagner builds. See 'That's A Mower, Eh?', 'Kinetic Choo Choo', and his race car tired amphibious Whymcycle, #115 in fact, 'Bounce For Glory'.
|Wikimedia Commons has media related to Eccentric-hub scooters.|
- Richard Rutherford's Scooter Patent US1664864, Rutherford, Richard, "Scooter", issued 03/04/1928 https://www.google.com/patents/US1664864
- Rollie Faegol's "Galloping Scooter" Patent US1679819, Fageol, Rollie, "Toy Vehicle", issued 07/08/1928 https://www.google.com/patents/US1679819
- Huysens' Self-Propelling Vehicle Patent US2125568, Huyssen, Philip & Prescott Huyssen, "Self-Propelling Vehicle", issued 02/08/1938 https://www.google.com/patents/US2125568
- Miller, Mary (1979). "The Incredible Ingo". Dave's Vintage Bicycles. Dave Stromberger. Retrieved 2012-07-17.
- The Three Stooges (1939-03-19). Yes, We Have No Bonanza (Film). Columbia Pictures.
- Curly on an Ingo-Bike from Yes, We Have No Bonanza https://www.youtube.com/watch?v=36kD4m7duEE
- The Kangaroo Scooter http://www.kangarooscooter.com
- "Bouncer Bike". New Ideas For Living. Retrieved 1 August 2012.