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Old 06-22-2013, 07:20 AM   #721
lnewqban
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Quote:
Originally Posted by joexr View Post
Your #2 is backwards. I think you're forgetting what the rake and trail are doing.
I cannot forget because I am not thinking.

My bike just rolls to the left each time I go to full left lock and lift my feet up from stopped vertical position.

Just try it and report back
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Old 06-22-2013, 07:41 AM   #722
Fajita Dave
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Quote:
Originally Posted by lnewqban View Post
I cannot forget because I am not thinking.

My bike just rolls to the left each time I go to full left lock and lift my feet up from stopped vertical position.

Just try it and report back
Due to the geometry of a motorcycle when you turn the handlebars left the tire's contact patch moves to the left of the CG. Because of this there is less weight being supported on the motorcycle right side. So the motorcycle will lean right when you turn the handlebars left even at a dead stop.

Being completely stopped and trying to balance 300+ pounds on a round surface with a 150+ Lbs lump of meat moving it around makes it extremely difficult to tell whats going on. If you lift one foot up a fraction of a second sooner than the other, the results will not be accurate. Not to mention your influence on the handlebars, if you pushed off slightly with one foot and which cheek of your back side you prefer to sit on (hardly anyone sites exactly centered on their seat). Its much easier and more accurate to look at what is mechanically going on which I explained in the first paragraph.

And yes I have tried it.
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Old 06-22-2013, 09:42 AM   #723
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Quote:
Originally Posted by Fajita Dave View Post
Due to the geometry of a motorcycle when you turn the handlebars left the tire's contact patch moves to the left of the CG. Because of this there is less weight being supported on the motorcycle right side. So the motorcycle will lean right when you turn the handlebars left even at a dead stop.

Being completely stopped and trying to balance 300+ pounds on a round surface with a 150+ Lbs lump of meat moving it around makes it extremely difficult to tell whats going on. If you lift one foot up a fraction of a second sooner than the other, the results will not be accurate. Not to mention your influence on the handlebars, if you pushed off slightly with one foot and which cheek of your back side you prefer to sit on (hardly anyone sites exactly centered on their seat). Its much easier and more accurate to look at what is mechanically going on which I explained in the first paragraph.

And yes I have tried it.
Thanks , I agree. I didn't have to try it to see either , I understand the geometry.
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Old 06-22-2013, 09:42 AM   #724
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Quote:
Originally Posted by lnewqban View Post
I cannot forget because I am not thinking.

My bike just rolls to the left each time I go to full left lock and lift my feet up from stopped vertical position.

Just try it and report back
What the hell are you doing this on?
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Old 06-22-2013, 12:41 PM   #725
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Quote:
Originally Posted by Fajita Dave View Post
Due to the geometry of a motorcycle when you turn the handlebars left the tire's contact patch moves to the left of the CG. Because of this there is less weight being supported on the motorcycle right side. So the motorcycle will lean right when you turn the handlebars left even at a dead stop........
Sorry, Dave, that is not how it works for my bike.
It is very evident, no hesitation or doubt, the bike falls on the left side each time, if it is close to vertical.

If you reconsider the steering geometry, you could see that the trail means that the contact patch is aft the steering axis a few inches and that it rotates off center the bike, but in the opposite direction toward which the handlebar steers.
As the front contact patch remains planted on the ground, the steering head column moves a little sideways toward the direction in which the handlebar steers.
It happens in cars as well.

http://www.dinamoto.it/dinamoto/8_on...ave/wobble.gif

For any bike, the CG remains aligned with the frame of the bike (between rear contact patch and the ground's projection of the axis of the steering column).

Playing with the handlebar is how Police riders can keep balance at extremely low speeds.

Not trying to prove you wrong, Sir, just making you take a closer look.
I have agreed with all your previous posts that I have read in this forum; there is no reason for not agreement on this point, IMHO.

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Old 06-22-2013, 02:24 PM   #726
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Quote:
Originally Posted by lnewqban View Post
Sorry, Dave, that is not how it works for my bike.
It is very evident, no hesitation or doubt, the bike falls on the left side each time, if it is close to vertical.

If you reconsider the steering geometry, you could see that the trail means that the contact patch is aft the steering axis a few inches and that it rotates off center the bike, but in the opposite direction toward which the handlebar steers.
As the front contact patch remains planted on the ground, the steering head column moves a little sideways toward the direction in which the handlebar steers.
It happens in cars as well.

http://www.dinamoto.it/dinamoto/8_on...ave/wobble.gif

For any bike, the CG remains aligned with the frame of the bike (between rear contact patch and the ground's projection of the axis of the steering column).

Playing with the handlebar is how Police riders can keep balance at extremely low speeds.

Not trying to prove you wrong, Sir, just making you take a closer look.
I have agreed with all your previous posts that I have read in this forum; there is no reason for not agreement on this point, IMHO.
You car falls over when you turn the wheel?
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Old 06-22-2013, 03:31 PM   #727
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Tried this on my Weestrom and 640 adventure. Both bikes seemed to have a 50/50 chance of falling toward or away from the direction I turned the bars when balancing at a standstill. Nothing consistent or obvious.
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Old 06-22-2013, 03:43 PM   #728
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Quote:
Originally Posted by Boon Booni View Post
Tried this on my Weestrom and 640 adventure. Both bikes seemed to have a 50/50 chance of falling toward or away from the direction I turned the bars when balancing at a standstill. Nothing consistent or obvious.
I tried it in the car , but it doesn't want to fall over either way. There's the possibility we're not drinking enough.
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Old 06-22-2013, 09:05 PM   #729
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Quote:
Originally Posted by lnewqban View Post
Sorry, Dave, that is not how it works for my bike.
It is very evident, no hesitation or doubt, the bike falls on the left side each time, if it is close to vertical.

If you reconsider the steering geometry, you could see that the trail means that the contact patch is aft the steering axis a few inches and that it rotates off center the bike, but in the opposite direction toward which the handlebar steers.
As the front contact patch remains planted on the ground, the steering head column moves a little sideways toward the direction in which the handlebar steers.
It happens in cars as well.

http://www.dinamoto.it/dinamoto/8_on...ave/wobble.gif

For any bike, the CG remains aligned with the frame of the bike (between rear contact patch and the ground's projection of the axis of the steering column).

Playing with the handlebar is how Police riders can keep balance at extremely low speeds.

Not trying to prove you wrong, Sir, just making you take a closer look.
I have agreed with all your previous posts that I have read in this forum; there is no reason for not agreement on this point, IMHO.
I'm all for constructive conversations! Arguing never gets anywhere.

Everything you said is absolutely right but I still see it as causing a "counter-steer" type reaction. As you said if you turn the handlebars right the steering column moves right. Due to the laws of inertia that movement alone would cause the motorcycle to lean left. An object at rest tries to stay at rest. If you move the steering column right but the chassis of the motorcycle tries to stay at rest, it will offset how the weight is being distributed from being centered (before steering movement) to offset to the left (after turning the handlebars right). This causes the motorcycle to lean left when the handlebars are turned right even at a stand still.

The link you provided of the bicycle is leaving out one very important aspect which is tire profile. When the steering is straight the contact patch of the tire is centered in the middle of the tread and in line with the wheel's axle. Because of the rake angle built into a motorcycle when you turn the handlebars the tire leans over and the contact patch is now offset from center. If you turn the handlebars right, the contact patch now moves off of center and to the right of the tire tread. This changes the center of gravity slightly because the contact patch is no longer centered with the wheel axle. This isn't a perfect analogy but I can't think of a better one right now. Imagine balancing a horizontal beam at its center. If you push the beam off that balance point from the right side, the beam will fall to the left.

There is something I could be missing or wrong about. I'm an experience mountain biker and doing track stands from a rolling stop differ from your experience. If I feel my balance falling to the right, I turn the handlebars right which cause the bike to lean back left extremely slightly to hold balance.
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Old 06-23-2013, 05:30 AM   #730
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Quote:
Originally Posted by joexr View Post
You car falls over when you turn the wheel?
No, no, Joe !!!
I referred to the little yaw of a car body when the tires are turned all the way to the left.
That is the whole reason of the trail in bicycles, shopping carts, tractors, cars, motorcycles, etc.: to naturally bring the contact patch of the tires to be in line with the axis around which they rotate to steer, so the vehicle has some directional self-stability.

You may not bother reading more about it, but for whoever else is interested:
http://en.wikipedia.org/wiki/Caster_...il_or_trailing

Quote:
Originally Posted by Fajita Dave View Post
.......There is something I could be missing or wrong about. I'm an experience mountain biker and doing track stands from a rolling stop differ from your experience. If I feel my balance falling to the right, I turn the handlebars right which cause the bike to lean back left extremely slightly to hold balance.
I understand your explanation, Dave, and I appreciate it.

Quote:
Originally Posted by Boon Booni View Post
Tried this on my Weestrom and 640 adventure. Both bikes seemed to have a 50/50 chance of falling toward or away from the direction I turned the bars when balancing at a standstill. Nothing consistent or obvious.
Thanks, Boon.
It seems that it does not work the same for every bike then.

Quote:
Originally Posted by Rucksta View Post
Has anybody figured out the geometry parameters that control the transition speed between
steering and counter steering and what affects the overlap between the two?

Even if you haven't figured it out it may be entertaining to hear some different theories.

It works as I described for my Ninja 250, reason for which I stand behind the concept that I tried to share via that little experiment, responding post #690 quoted above.

Starting moving from full left lock and vertical position, my bike tends to roll to the left first and then, while the speed increases, it rolls to the right.
If I keep moving it slow enough, there is no counter-steering effect.

That has been my experience; however, according to other posters, it seems to happen in a different way for heavier bikes with wider tires, I don't know.

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Old 06-23-2013, 12:38 PM   #731
David R
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Riding my motorcycle coming to a stop. Right foot on the brake, left foot as landing gear.

IF the bike does not want to lean to the left so my left foot can catch it, I TURN TO THE RIGHT so the bike falls to the left. Do not speculate go ride the bike and see for your self.

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Old 06-24-2013, 08:42 PM   #732
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Sitting in my normal riding position on a KTM 500 EXC with supermoto setup (that's 17" wheels for the most part) ... balance, pick my feet up, turn left, bike falls 50/50 left or right. If I sit forward or lean forward, balance, pick my feet up, turn left, bike falls left. Sit back or lean back, balance, pick my feet up, turn left, bike falls right.



Think Im going to unsubscribe from this thread before my wife divorces me because Im in the garage acting out scenarios trying to settle an argument between me and myself.
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Old 06-25-2013, 02:44 PM   #733
Fajita Dave
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Quote:
Originally Posted by lnewqban View Post


Starting moving from full left lock and vertical position, my bike tends to roll to the left first and then, while the speed increases, it rolls to the right.
If I keep moving it slow enough, there is no counter-steering effect.

That has been my experience; however, according to other posters, it seems to happen in a different way for heavier bikes with wider tires, I don't know.
This will probably sound like a snide remark but answer me this. If the underlined statement is what you're experiencing then at what point does turning the handlebars do absolutely nothing?

From your experience at some point there needs to be a transition from direct steering to counter-steering. This means if you were to ride right in that transition point, steering will do absolutely nothing.
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Old 06-25-2013, 07:28 PM   #734
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[From your experience at some point there needs to be a transition from direct steering to counter-steering. This means if you were to ride right in that transition point, steering will do absolutely nothing.[/QUOTE]This is a classic.
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Old 06-26-2013, 07:54 AM   #735
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Quote:
Originally Posted by Fajita Dave View Post
This will probably sound like a snide remark but answer me this. If the underlined statement is what you're experiencing then at what point does turning the handlebars do absolutely nothing?

From your experience at some point there needs to be a transition from direct steering to counter-steering. This means if you were to ride right in that transition point, steering will do absolutely nothing.
Now you know why so many inexperienced riders -including some that have been riding for decades- go virtually straight in a turn that is to them unexpectedly tight.
They were all riding at that transition point, no amount of steering could get them through that turn.
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