3,693
edits
(10 intermediate revisions by 2 users not shown) | |||
Line 109: | Line 109: | ||
===Once lean is achieved=== | ===Once lean is achieved=== | ||
As the desired angle is approached, the front wheel must then be steered into the turn to maintain that angle or the bike will continue to lean with gravity, increasing in rate, until the side contacts the ground. This process usually requires little physical effort, because the | As the desired angle is approached, the front wheel must then be steered into the turn to maintain that angle or the bike will continue to lean with gravity, increasing in rate, until the side contacts the ground. This process usually requires little physical effort, because the geometry of the steering system of most bikes is designed in such a way that the front wheel has a strong tendency to steer in the direction of a lean. | ||
The actual torque the rider must apply to the handlebars to maintain a steady-state turn is a complex function of bike geometry, mass distribution, rider position, turn radius, and forward speed. At low speeds, the steering torque necessary from the rider is usually negative, that is opposite the direction of the turn, even when the steering angle is in the direction of the turn. At higher speeds, the direction of the necessary input torque often becomes positive, that is in the same direction as the turn.<ref name="Cossalter">{{cite book | The actual torque the rider must apply to the handlebars to maintain a steady-state turn is a complex function of bike geometry, mass distribution, rider position, turn radius, and forward speed. At low speeds, the steering torque necessary from the rider is usually negative, that is opposite the direction of the turn, even when the steering angle is in the direction of the turn. At higher speeds, the direction of the necessary input torque often becomes positive, that is in the same direction as the turn.<ref name="Cossalter">{{cite book | ||
Line 127: | Line 127: | ||
===At low speeds=== | ===At low speeds=== | ||
At low speeds countersteering is equally necessary, but the countersteering is then so subtle that it is hidden by the continuous corrections that are made in balancing the bike, often falling below a | At low speeds countersteering is equally necessary, but the countersteering is then so subtle that it is hidden by the continuous corrections that are made in balancing the bike, often falling below a just noticeable difference or threshold of perception of the rider. Countersteering at low speed may be further concealed by the ensuing much larger steering angle possible in the direction of the turn. | ||
===Unconscious behavior=== | ===Unconscious behavior=== | ||
Countersteering is indispensable for bike steering. Most people are not consciously aware that they employ countersteering when riding their bike any more than they are aware of the physics of walking. They have learned to subsconciously apply the required countersteering. | Countersteering is indispensable for bike steering. Most people are not consciously aware that they employ countersteering when riding their bike any more than they are aware of the physics of walking. They have learned to subsconciously apply the required countersteering. | ||
===Gyroscopic effects=== | ===Gyroscopic effects=== | ||
One effect of turning the front wheel is a roll | One effect of turning the front wheel is a roll moment caused by gyroscopic precession. The magnitude of this moment is proportional to the moment of inertia of the front wheel, its spin rate (forward motion), the rate that the rider turns the front wheel by applying a torque to the handlebars, and the cosine of the angle between the steering axis and the vertical.<ref name="Cossalter"/> | ||
For a sample motorcycle moving at 22 m/s (50 mph) that has a front wheel with a moment of inertia of 0.6 kgm<sup>2</sup>, turning the front wheel one degree in half a second generates a roll moment of 3.5 Nm. In comparison, the lateral force on the front tire as it tracks out from under the motorcycle reaches a maximum of 50 N. This, acting on the 0.6 m (2 ft) height of the center of mass, generates a roll moment of 30 Nm.<ref name="Cossalter"/> | For a sample motorcycle moving at 22 m/s (50 mph) that has a front wheel with a moment of inertia of 0.6 kgm<sup>2</sup>, turning the front wheel one degree in half a second generates a roll moment of 3.5 Nm. In comparison, the lateral force on the front tire as it tracks out from under the motorcycle reaches a maximum of 50 N. This, acting on the 0.6 m (2 ft) height of the center of mass, generates a roll moment of 30 Nm.<ref name="Cossalter"/> | ||
Line 182: | Line 180: | ||
| accessdate = 2009-12-31}}</ref> and is summed up in a simplified way as "Push the right-hand bar to steer right; push the left-hand bar to steer left". | | accessdate = 2009-12-31}}</ref> and is summed up in a simplified way as "Push the right-hand bar to steer right; push the left-hand bar to steer left". | ||
==The Wright Brothers== | ==The Wright Brothers== | ||
Wilbur Wright explains countersteering this way: | |||
{{Quote| | {{Quote| | ||
Line 208: | Line 204: | ||
==External links== | ==External links== | ||
*[http://www.tonyfoale.com/Articles/Balance/BALANCE.htm Balance and Steering], by | *[http://www.tonyfoale.com/Articles/Balance/BALANCE.htm Balance and Steering], by Tony Foale | ||
*[http://www.superbikeschool.com/machinery/no-bs-machine.php "No B.S. Machine"] physical experimentation | *[http://www.superbikeschool.com/machinery/no-bs-machine.php "No B.S. Machine"] physical experimentation | ||
[[Category:Motorcycle riding techniques]] | [[Category:Motorcycle riding techniques]] | ||
[[Category:Motorcycle | [[Category:Motorcycle physics]] | ||
[[Category:Motorcycles]] | |||
[[Category:Mopeds]] | [[Category:Mopeds]] |
edits