On Wed, 12 Feb 2014 17:41:25 -0500, KC wrote:

On 2/12/2014 5:14 PM, Poco Loco wrote:
On Wed, 12 Feb 2014 16:21:26 -0500, KC wrote:

On 2/12/2014 3:52 PM, Poco Loco wrote:
On Wed, 12 Feb 2014 15:15:41 -0500, KC wrote:

On 2/12/2014 12:35 PM, Poco Loco wrote:
On Wed, 12 Feb 2014 11:44:07 -0500, KC wrote:

On 2/12/2014 11:20 AM, Poco Loco wrote:
On Wed, 12 Feb 2014 10:33:01 -0500, KC wrote:

On 2/12/2014 10:06 AM, Mr. Luddite wrote:
On 2/12/2014 9:42 AM, Poco Loco wrote:
On Wed, 12 Feb 2014 09:06:41 -0500, BAR wrote:

In article ,
__ says...

Mr. Luddite wrote:
On 2/9/2014 6:25 PM, Poco Loco wrote:
On Sun, 9 Feb 2014 15:03:40 -0800 (PST), Tim
wrote:

On Sunday, February 9, 2014 4:30:04 PM UTC-6, John H. wrote:
On Sun, 9 Feb 2014 13:31:40 -0800 (PST), Tim
wrote:



On Sunday, February 9, 2014 7:31:31 AM UTC-6, F.O.A.D. wrote:

I'd love to have one of these...







http://www.youtube.com/watch?v=U7mTwM7afQA





how about something like this?



http://thekneeslider.com/1937-front-...cle-prototype/







Looks like something Moto Guzzi made during the war.

"Goose" probably tries something like that too, but this is French,
and the French at that time were known to be great tinkerers, with
results to match.

Yeah, I should have said it looks like something Guzzi *could* have
made during the war. Something
like this:

http://www.youtube.com/watch?v=4cOlS_ShXf4



Here's an idea for Scott: (warning - contains boating content)

http://www.elrellano.com/videos_online/8146/barca-a-motor.html


No steering unless that rowboat has a bow thruster.

Just like a motor cycle, you just lean into the turn to make it go
that way.

No, leaning doesn't make it turn. Leaning enables the motorcycle to be
kept more vertical when
turning. Pushing on the handlebar makes you turn. Push left, go left.
Push right, go right.
Countersteering.


Heh. I just mentioned to Scott about that. Those who don't ride will
think it's weird. They think it should turn like a car.



Yes, counter steering but again, it's not the fastest way around the
corner

It's the only way around the corner, at speed, on a motorcycle.


I am beating myself up and I can't think of any place on the track where
counter steering is faster...

https://www.facebook.com/photo.php?fbid=10202016412913497&set=a.10202016402 113227.1073741828.1281248494&type=3&theater

Here is Jess setting up for a corner... notice she is turning left, and
her bars are slightly left.. If she let her back tire slide out more
(blowing the corner) the bike would have to stand back up and the back
tire come back in line to get out of the corner... don't know if that
makes any sense. I have a video I could find later of two riders me and
Jess study. One came though the corner right (her mentor) and the guy
behind counter steered through and lost two seconds in the corner...

Letting the back tire 'slide out more' is not a method of riding for anyone but dirt bikers. When
she initiated the turn to the left, she did it by pushing on the left bar or pulling on the right
bar. Once the bike started leaning (and turning) she can slide all she wants.

I think what she is doing in the picture is coming out of a turn. So she's pushing on the right bar
to straighten the bike up (or pulling on the left bar). Looking at the tracks in the dirt also shows
that she's through the turn.


That picture is in the first 30 feet of the turn.. and no. She doesn't
have to push the left down to initiate the turn. Some turns she comes
into airborne and she already has the bars turned in the direction of
the turn... I see completely what you guys are talking about. I have had
a mc licence since '76 and always thought that way... Until I started
training Jess. She comes into a corner and throws her weight over the
bike.. but pushes both bars down... the outside bar further... never the
inside bar, never let that rear tire get outside of the radius of the
front tire...... Just the way it is. Again, if she pushes down on the
inside bar, the rear tire kicks outside the radius of the inside tire.
now you have thrust pushing askew from the direction of the bike... we
calle it "wash out" or "blowing the berm".. draw it out, put arrows for
thrust.. You will see...

Uh-huh. I just hope Jess, while on pavement going at speed, doesn't ever push left to go right.
Something will get broke.


OK, let's go from there.. When you are countersteering on the street, by
design the thrust of the rear tire and front tire are not in sync with
the direction of the turn.. So which tire do you slide?

Just so you don't think I'm lying to you:

http://en.wikipedia.org/wiki/Countersteering

Countersteering is the technique used by single-track vehicle operators, such as cyclists and
motorcyclists, to initiate a turn toward a given direction by momentarily steering counter to the
desired direction ("steer left to turn right"). A more accurate term is deliberate countersteering
when employed by a rider, though it is often shortened to just countersteering. To negotiate a turn
successfully, the combined center of mass of the rider and the single-track vehicle must first be
leaned in the direction of the turn, and steering briefly in the opposite direction causes that
lean.[1] This technique does not apply to conventional multiple-tracked vehicles such as trikes or
sidecar-equipped bicycles and motorcycles.

How it works[edit]

A single-track vehicle such as a bicycle or a motorcycle is an inverted pendulum—it will fall over
unless balanced.
The technique used by cyclists and motorcyclists to initiate turning in a given direction is to
first apply a steering torque in the opposite direction. For example, if a turn to the left is
desired, it is started by applying a torque on the handlebars to the right. This causes the front
wheel to rotate about the steering axis to the right and the front tire will generate forces in the
contact patch to the right. The machine as a whole steers to the right briefly, and because the
forces in the contact patch are at ground level, this pulls the wheels "out from under" the bike to
the right and causes it to lean to the left. Then the rider, or in most cases, the inherent
stability of the bike provides the steering torque necessary to rotate the front wheel back to the
left and in the direction of the desired turn. Finally, the bike begins a turn to the left.[11] It
is often boiled down to "push left to go left".
While this appears to be a complex sequence of motions, it is performed by every child who rides a
bicycle. The entire sequence goes largely unnoticed by most riders, which is why some assert that
they do not do it.
It is often claimed that two-wheeled vehicles can be steered using only weight shifts. While this is
true for small "trim" inputs to direction, complex maneuvers are not possible using weightshifting
alone because even for a light machine there is insufficient control authority.[12] Although on a
sufficiently light bike (especially a bicycle), the rider can initiate a lean and turn by shifting
body weight,[6] there is no evidence that complex maneuvers can be performed by bodyweight alone.[9]
It is also important to distinguish the steering torque necessary to initiate the lean required for
a given turn from the sustained steering torque and steering angle necessary to maintain a constant
radius and lean angle until it is time to exit the turn. The initial steer torque and angle are both
opposite the desired turn direction. The sustained steer angle is in the same direction as the turn.
The sustained steer torque required to maintain that steer angle is either with or opposite the turn
direction depending on forward speed, bike geometry, and combined bike and rider mass distribution.
Deliberate countersteering is necessary to adjust the angle of lean of a bike and works in the
opposite sense to the handlebar input while conventional steering in the direction of the turn is
used to negotiate the turn.
Need to lean to turn[edit]
A bike can negotiate a curve only when the combined center of mass of bike and rider leans toward
the inside of the turn at an angle appropriate for the velocity and the radius of the turn:
\theta =\arctan \left({\frac {v^{2}}{gr}}\right)
where v is the forward speed, r is the radius of the turn and g is the acceleration of gravity.[6]
Higher speeds and tighter turns require greater lean angles. If the mass is not first leaned into
the turn, the inertia of the rider and bike will cause them to continue in a straight line as the
tires track out from under them along the curve. The transition of riding in a straight line to
negotiating a turn is a process of leaning the bike into the turn, and the most practical way to
cause that lean (of the combined center of mass of bike and rider) is to move the support points in
the opposite direction first.[13] The rider can shift his weight of course, but any force used to
move one way laterally pushes the bike laterally the opposite direction with equal force. That makes
the bike lean (and can affect the steering), but it does not change the combined center of mass of
bike and rider.
Lean by countersteering[edit]
When riding a bicycle or a motorcycle, deliberate countersteering is a method of initiating a turn
by a small, momentary turn of the front wheel, usually via the handlebars, in the opposite (counter)
direction. This moves the pivot point (the wheels' contact patches) out from under the center of
mass to establish the lean angle for a turn. While exploitable at all speeds, the need to
deliberately countersteer becomes more noticeable as speed increases.
Hence, to turn to the right, the rider first throws the bike off balance by momentarily pointing the
front wheel slightly to the left. The center of mass of the bike plus rider will continue in a
straight line, but the contact patches of the tires move to the left with respect to this straight
line.
Once lean is achieved[edit]
As the desired angle is approached, the front wheel must usually 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 often requires little or no 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, tire properties, 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.[14]
Adjusting or exiting a turn[edit]
Once in a turn, deliberate countersteering is again required to make changes to its shape. The only
way to decrease the radius at the same speed is to increase the lean angle, and the most effective
way to increase the lean angle, is again to momentarily steer opposite to the direction of the
curve. To the untrained, this can be extremely counter-intuitive.
To exit a turn, a deliberate countersteer by momentarily steering further in the direction of the
turn will tilt the bike back upright.
At low speeds[edit]
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.
Unthinking behavior[edit]
Countersteering is indispensable for bike steering. Most people are not aware that they employ
countersteering when riding their bike any more than they are aware of the physics of walking. They
have learned to apply the required countersteering without thinking.
As is well known in bicycle racing, the countersteering phenomenon becomes evident when there is an
obstacle preventing the wheel from countersteering (e.g., when closely overlapping wheels or riding
very close to a curb). In these situations, the way to initiate a turn with the handlebars away from
the obstacle is to countersteer towards obstacle to avoid crashing into it.[13] Lack of
understanding of this principle leads to accidents in novice bicycle races.
Gyroscopic effects[edit]
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.[14]
For a sample motorcycle moving at 22 m/s (50 mph) that has a front wheel with a moment of inertia of
0.6 kgm2, 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.[14]
While the moment from gyroscopic forces is only 12% of this, it can play a significant part because
it begins to act as soon as the rider applies the torque, instead of building up more slowly as the
wheel out-tracks. This can be especially helpful in motorcycle racing.[14]
No hands[edit]


Oh, so it's something you do once in a while.. I get it.. So, I can push
my right bar to turn left if I want to... got it...

Yeah, when you want to turn. The rest of the time you don't do it.

Hey, you're cool. Try turning right by pushing right.