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Counter Steering | The interesting physics behind it - YouTube
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- [Narrator] Countersteering
is an amazing technique
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used by many bike riders
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and is very useful in making a quick turn,
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and doing some bike stunts like this.
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At first, countersteering
looks counter-intuitive.
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You turn the handlebars to the left,
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but the motorcycle makes
a quick right turn.
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What are the physics behind
this strange phenomenon?
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Let's explore.
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Before understanding the
physics behind countersteering,
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we need to understand the physics
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behind normal motorcycle steering
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and no-slip wheel condition.
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First, let's explore what is meant
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by this no-slip condition.
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The wheels are always trying
to attain a non-slip condition,
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which means that the wheels
should have no relative motion
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with the road.
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Since the road is at rest,
the wheel contact point
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should have zero velocity.
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But how is zero velocity
possible for a moving wheel?
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It is possible because the
wheel has two kinds of motion,
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a translational motion
along with the vehicle
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and a rotational motion on its own axis.
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You can see that it is possible
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to make the resulting velocity
zero at the contact point,
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since the translational
and rotational velocities,
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are in opposite directions.
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In normal steering, to make a right turn,
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what we do is just turn the
handlebars towards the right
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and lean the motorcycle inwards.
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Let's analyze the normal
steering operation
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in a step-by-step manner,
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to understand the physics behind it.
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Assume that even after
turning the handlebars,
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the vehicle moves straight ahead.
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Here, if you check the front wheel,
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it will not meet the no-slip condition,
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since the wheel and vehicle velocities
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do not cancel each other out.
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The only way to solve this problem
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is by making the translational
velocity inclined as well.
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This is possible when the
whole motorcycle makes a turn
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around an instantaneous center.
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The instantaneous center
should be at the intersection
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of both the wheels' normal lines.
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It's clear that when the
motorcycle makes a turn
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in this manner, both the
wheels easily satisfy
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the no-slip condition.
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In short, the no-slip condition
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forces the motorcycle to make a turn.
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However, a centripetal force is needed
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for any object to make a turn.
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This centripetal force is
provided by the frictional force
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between the tire and the road.
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Let's do the torque
balance of the motorcycle,
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at one point during the turn.
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You can see that the vehicle
is not stable in this position.
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The torque produced by
the frictional forces
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will turn the motorcycle down.
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The only way to balance this torque
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is by leaning your motorcycle inwards.
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You can see how the gravitational
and normal forces act
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in the inclined motorcycle position.
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This will produce another
torque, which can counter
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the torque formed by
the centripetal force.
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This is the way you
normally turn the vehicle.
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You turn the handlebars to
balance the torque produced
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by the centripetal force,
just lean the motorcycle.
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Here, the rider has to
adjust his body position
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to achieve the lean of the motorcycle.
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Note that the handlebars turning
and the leaning operation
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happen simultaneously and
are in perfect balance.
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How is countersteering
different from normal steering?
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In countersteering, you
turn the handlebars,
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however, you do not lean the motorcycle.
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Obviously, this is an unstable condition.
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The torque produced by
the centripetal force
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will topple the motorcycle
in the opposite direction.
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In short, the motorcycle achieves a lean
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in the opposite direction for a moment.
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This lean is sufficient
to achieve a perfect turn
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in the opposite direction.
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One thing to be noted here
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is that during the lean operation,
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the driver cleverly adjust
the angle of the handlebars
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so that it is suitable for
a perfect no-slip condition.
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In short, in normal steering,
the lean of the motorcycle
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is achieved by shifting your body weight.
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In counter steering, the lean is achieved
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by the motorcycles instability
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caused by the centripetal force.
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Obviously, countersteering
is a quicker operation
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but slightly risky.
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If you don't steer the handlebars
back to the proper angle
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during the leaning operation,
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you are going to fall down.
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This is why proper practice is needed
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to master this instability steering trick.
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Countersteering is quite handy
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to avoid sudden obstacles in the road.
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Let's see how it works in practice.
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- The trick of countersteering
is that you turn the handle,
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but don't lean.
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Also practice it well.
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(upbeat music)
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- [Narrator] It is clear
from this demonstration
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that by turning the
handlebars to the left,
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the rider was able to shift the motorcycle
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to the right side.
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Obviously, the counter
steering is a quicker method
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to avoid sudden obstacles.
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We hope you have enjoyed the
science behind countersteering
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and wish you all the best
in mastering this art.
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Please don't forget to support us
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by clicking the help button.
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Thank you.
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