CounterSteering

Countersteering

The definition I’m going to use for countersteering is: If you turn the handlebars while the bike is in motion to the left the bike will rotate clockwise and if you turn the handlebars to the right the bike will rotate counterclockwise. This rotation is around the motorcycle's Center of Gravity (CG) not around the tire's contact patch. This has nothing to do with leaning left or right, although that’s what happens if you started from an upright position. It works at high speed and it works at low speed, it works the same way at all speeds, it’s just that you can see it easier at lower speeds. I’m also going to define something I’ll call "The Contact Patch Axis"(CPA) as being the line between where the front tire touches the ground and where the rear tire touches the ground and I’m going to define leaning to the left as the situation where the (CG) is to the left of the CPA and leaning to the right as the situation where the CG is to the right of the CPA. Straight up will be the situation where the CG is in that precariously unstable position directly above the CPA. Because the CG is directly above the CPA when driving straight down the road the force moving the tire to the right when you turn the handlebars to the right causes a torque that rotates the motorcycle counterclockwise. This is like you standing on a rug and having someone pull it out from under you towards your right. You would lean to the left. If you leave the motorcycle in this state it will eventually fall all the way over onto it’s left side. To prevent this you must move the handlebars to the left until the front tire is pointing to the left. As the front tire passes the straight ahead position the bike stops its counterclockwise rotating due to countersteering but because it is now leaning to the left it would continue to fall to the left due to the pull of gravity on the CG . Sooooo you must turn the wheel past the center position and to the left to create the same effect that caused the lean in the first place (countersteering). Only this time the force you create causes the bike to rotate clockwise. However, since you didn’t start from a balanced upright position there is the force of gravity still pulling the bike down in a counterclockwise rotation. When you have the proper amount of left turn input to the handlebars the force of gravity rotating the bike counterclockwise will be offset by the countersteering that is now rotating the bike clockwise and you are now in a steady state turn to the left which you can hold until you run out of road.

At the end of the turn when you wish to bring the bike back to an upright position from it’s current left leaning condition you move the handlebars more to the left than is necessary to balance the bike in the turn and that countersteering generates a rotation in a clockwise direction. When the bike is upright again you straighten the handlebars so the front tire is pointing straight ahead and the bike will continue straight ahead. If you do not straighten the handlebars and continue to hold them pointing to the left the bike will pass over the upright position and continue to rotate clockwise and you will start a lean to the right and the beginnings of a right turn.

Steady State Turning

In order to turn you bike to the left the front tire must be turned to the left. In order to turn to the right the front tire must be turned to the right. Once you've established your lean angle, your bike can only go in the dirction that the front tire is pointing. Turning to the left doen't mean turning your front wheel to the right and holding that position. If the front wheel is held to the right you would continue to rotate counterclockwise until your left foot peg, left knee, left handlebar, left shoulder, etc, etc, hit the ground and you crashed on your left side. You do not just turn your front wheel to the right in order to go to the left. You turn your front wheel to the right in order to lean the bike to the left and when it is leaning enough you must turn your front wheel to the left in order to continue on a steady state left turn.

Gyroscopes

The gyroscopic effect of the front wheel has nothing to do with steering a motorcycle. As shown above, you start turning a motorcycle to the left by turning the front wheel to the right to begin leaning the bike counterclockwise. Once you've reached the desired lean angle you must turn the front wheel to the left in order to create a countersteering effect in a clockwise direction to offset the force of gravity that is pulling your bike in a counterclockwise direction. But if gyroscopic effect had caused the bike to lean to the left when you moved the front wheel to the right then gyroscopic effect would cause to bike to lean to the right when you move the front wheel to the left to continue making the left hand turn. But the bike doesn't stand up, it just continues turning to the left while leaning to the left. Gyroscopic effect of the front wheel turning left and right doesn't have any effect on whether the bike is leaning left or right. The only thing that gyroscopic effect of the front wheel will affect is how hard it is to turn the wheel left and right. A heavier wheel will take more force to turn, tiring you out sooner that a lighter wheel would.

Another case that proves that gyroscopic effect isn't causing a bike to rotate left and right is a high speed tankslapper. If gyroscopic effect made the bike rotate then having your handlebars move from full lock left to full lock right and back to the left would make your motorcycle rotate left and right. But it doesn't. The bike just keeps going straight down the road because during a tankslapper the tire doesn't make full contact with the road, just a light contact that generates enough force to move the wheel in the oposite direction from where it's pointing when it hit the road. This is due to the trail that the bike has.

Another case againt gyroscopic force rotating a bike is when poping a wheelie and turning the front wheel. The bike doesn't rotate. Gyroscopic effect has no affect on the leaning of a bike at all.

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