Mostrar código-fonte de Shimmy

'''Wobble''', '''shimmy''', '''tank-slapper''',<ref>{{Cite book |last=Hough |year=2000 |first=David L. | author-link=David_L._Hough |title=Proficient Motorcycling: The Ultimate Guide to Riding Well |edition=2nd |publisher=BowTie Press|location=USA | url=http://books.google.com/books?id=yeAIAIxS-cgC |isbn=1889540536 |page=253 |chapter=Glossary |quote='''tank slapper:''' a speed wobble so severe that the handlebars bang alternately against the sides of the fuel tank }}</ref> '''speed wobble''', e '''death wobble''' são palavras para descrever um rápido movimento que acontece nas rodas de veículos como [[carro]]s e [[motocicleta]]s devido a oscilações  (geralmente entre 4 e 10&nbsp;Hz) ou por falta de ajuste na [[cambagem]] (em carros), ou por [[ângulo de caster]] muito alto (em motos), podendo causar a queda do piloto ou até mesmo um acidente grave. O efeito também pode ser observado em [[jipe]]s, [[skate]]s, [[patins]] e em qualquer veículo que possuem como guia, uma roda.<ref name="Wilson">{{cite book
| title = Bicycling Science
| edition = Third Edition
| last = Wilson
| first = David Gordon  
| coauthors = Jim Papadopoulos
| year = 2004
| publisher = The MIT Press
| isbn = 0-262-73154-1
| pages = 263–390}}</ref><ref name="Cossalter">{{cite book
| title = Motorcycle Dynamics
| edition = Second Edition
| last = Cossalter
| first = Vittore  
| year = 2006
| publisher = Lulu.com
| isbn = 978-1-4303-0861-4
| pages = 241–342}}</ref>

<!--
== Theory ==
Sustained oscillation has two necessary components: An '''underdamped second order or higher system''' and a '''[[positive feedback]] mechanism'''. An example of an underdamped second order system is a [[damping|spring and mass system]] where the mass can bob up and down (oscillate) when hanging from a spring.

== In bikes ==
Wobble or shimmy begins when some otherwise minor irregularity accelerates the wheel to one side. The restoring force is applied in phase with the progress of the irregularity, and the wheel turns to the other side where the process is repeated. If there is insufficient [[steering damper|damping]] in the steering the oscillation will increase until system failure. The oscillation frequency can be changed by changing the forward speed, making the bike stiffer or lighter, or increasing the stiffness of the steering, of which the rider is a main component.<ref name="Wilson" /> While wobble or shimmy can be easily remedied by adjusting speed, position, or grip on the handlebar, they can be fatal if left uncontrolled.<ref>{{cite news
| title = Crash kills cyclist
| last = Kettler
| first = Bill 
|date=2004-09-15
| work = Mail Tribune
| url = http://www.mailtribune.com/archive/2004/0915/local/stories/01local.htm
| accessdate = 2006-08-04
}}</ref>

Since shimmy frequency is independent of bike speed, gyroscopic effects "are clearly not essential to the phenomenon."<ref name="Wilson" /> The top five influences on wobble have been found to be lateral stiffness of the front tire, steering damper, height of bike center of mass, distance of bike center of mass from rear wheel, and cornering stiffness of the front tire.<ref name="Cossalter"/>

An academic paper that investigated wobble through physical experimentation and computer modeling, concludes "the influence on wobble mode of front tyre characteristics, front frame inertia and chassis stiffness were shown. In particular, it shows that increasing front tire inflation, stiffness chassis, and front frame inertia about steering axis and decreasing sideslip stiffness of front tire, wobble mode damping is improved, promoting vehicle stability."<ref>{{cite conference  | first = Salvador  | last = Mauro  | authorlink =   | coauthors = Fabris, Davide  | title = Study of stability of a two wheeled vehicle through experiments on the road and in laboratory  | date = May 27-28, 2004  | location = Modena, Italy  | url = http://www.dinamoto.it/DINAMOTO/papers%20MDRG/_MDRG%20Papers%20in%20PDF%20format/2004_04%20Study%20of%20stability%20of%20a%20two%20wheeled%20vehicle%20MODENA.pdf  | format = [[PDF]]  | doi =   | id =   | accessdate = 2008-08-31}}</ref>
-->
== {{Ver também}} ==
* [[Ângulo de caster]]
* [[Cambagem]]

{{Ref-section}}

== {{Ligações externas}} ==
* [http://www.sheldonbrown.com/brandt/shimmy.html Bicycle speed wobbles]
* [http://www.flyingsnail.com/Sprung/tankslapper.html Video de um motociclista sofrendo o shimmy]
* [http://www2.ee.ic.ac.uk/cap/cappp/projects/2/files/wobble_0_65.avi Animação de um shimmy]
<!--*[http://www.youtube.com/watch?v=i5Dapy1xUq0&mode=related&search= Video de um acidente de bike, devido o shimmy]
* [http://www.youtube.com/watch?v=wj9PNNChVm4 Video de um acaminhão com shimmy] youtube não permitido-->

[[Categoria:Motociclismo]]
[[Categoria:Automobilismo]]