Editing Countersteering (section)

==Countersteering by weight shifting==
With a sufficiently light bike (especially a [[bicycle]]), the rider can initiate a lean and turn without using the handlebars by shifting body weight, called '''counter lean''' by some authors.<ref name="fajans">{{cite journal
| journal = American Journal of Physics
| volume = 68
| issue = 7
|date=July 2000
| last = Fajans
| first = Joel
| title = Steering in bicycles and motorcycles
| url = http://socrates.berkeley.edu/~fajans/pub/pdffiles/SteerBikeAJP.PDF
| access-date = 4 August 2006
| pages = 654–659
| doi = 10.1119/1.19504
| bibcode=2000AmJPh..68..654F}}</ref><ref name="evangelou">Evangelou, S, 2004 "The Control and Stability Analysis of Two-Wheeled Road Vehicles", PhD Thesis, Imperial College London</ref><ref name="Cocco">
{{cite book
| title = Motorcycle Design and Technology
| last = Cocco
| first = Gaetano
| publisher = Motorbooks
| year = 2004
| page = 25
| isbn = 978-0-7603-1990-1}}</ref><ref name="Foale">{{cite book
| title = Motorcycle Handling and Chassis Design, the Art and Science
| edition = 2nd
| last = Foale
| first = Tony
| publisher = Tony Foale Designs
| year = 2006
| pages = 4–7
| isbn = 978-84-933286-3-4}}</ref>
Documented physical experimentation shows that on heavy bikes (many [[motorcycle]]s) shifting body weight is less effective at initiating leans.<ref name="code">{{cite magazine
| url = http://www.popularmechanics.com/outdoors/outdoors/1277436.html
| access-date = 7 August 2006
| title = STEER GEAR So how do you actually turn a motorcycle?
| last = Gromer
| first = Cliff
| date = 1 February 2001
| magazine = Popular Mechanics
| archive-url = https://web.archive.org/web/20100126033625/http://www.popularmechanics.com/outdoors/outdoors/1277436.html
| archive-date = 26 January 2010}}</ref>

The following is done when countersteering using weight shifting to turn left:

* The rider applies a momentary torque, either at the seat via the legs or in the torso that causes the bike itself to lean to the right.
* The combined center of mass of the bike and rider is only lowered and not moved out, but if the front of the bike is free to swivel about its steering axis, the lean to the right will cause it to steer to the right by some combination of gyroscopic precession, ground reaction forces, gravitational force on an off-axis center of mass or simply the inertia of an off-axis center of mass depending on the exact geometry and mass distribution of the particular bike and the amount of torque and the speed at which it is applied.<ref name="fajans"/><ref name="Brandt">{{cite web
| title = What keeps the bicycle upright?
| url = http://www.sheldonbrown.com/brandt/gyro.html
| last = Brandt
| first = Jobst
| date = 16 September 1997
| publisher = sheldonbrown.com
| access-date = 17 October 2007}}</ref>
* This countersteering to the right causes the ground contact to move to the right of the center of mass, as the bike moves forward, thus generating a leftward lean. Finally the front end steers to the left and the bike enters the left turn.

The amount of leftward steering necessary to balance the leftward lean appropriate for the forward speed and radius of the turn is controlled by the torque generated by the rider, again either at the seat or in the torso.

To straighten back out of the turn, the rider simply reverses the procedure for entering it: cause the bike to lean farther to the left; this causes it to steer farther to the left, which moves the wheel contact patches farther to the left, eventually reducing the leftward lean and exiting the turn.

A [[National Highway Traffic Safety Administration]] study showed that rider lean has a larger influence on a lighter motorcycle than a heavier one,<ref>{{citation|title=Motorcycle Safety Improvement |volume=2 |author=Anil V. Khadilkar |author2=R. Nichols |author3=R. Schwarz|publisher=United States Department of Transportation, National Highway Traffic Safety Administration|year=1977|chapter=Analytical results: influence of rider lean angle|page=4-24<!-- four-dash-twenty-four is a single page-->|chapter-url=https://books.google.com/books?id=7tIyB8kL81EC&pg=SA4-PA4}}</ref> which helps explain why no-hands steering is less effective on heavy motorcycles. Leaning the torso with respect to the bike does not cause the bike to lean far enough to generate anything but the shallowest turns. No-hands riders may be able to keep a heavy bike centered in a lane and negotiate shallow highway turns, but not much else.

Complex maneuvers are not possible using weight shifting alone because even for a light machine there is insufficient control authority.<ref name="evangelou"/>
Although on a sufficiently light bike (especially a [[bicycle]]), the rider can initiate a lean and turn by shifting body weight,<ref name="fajans"/> there is no evidence that complex maneuvers can be performed by bodyweight alone.<ref name="code"/>