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Old 06-18-2013, 06:58 AM   #691
lnewqban
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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.
That is something that anyone can find experimentally:

1) From total stop, balance the bike vertically, put both feet up on the pegs.
From that position, if you don't turn the handlebar, the bike will fall to either side.
Repeat and verify: the bike has no preferred side to fall onto.


2) From total stop, balance the bike vertically, put both feet up on the pegs.
From that position, turn handlebar all the way to the left (full lock), the bike will consistently fall to the left side.
Why?: You have moved the CG of the bike left and is now off the line that joins the contact patches of the front and rear tires.
That is steering for you, and will work for standing still and for low speeds.


3) Next, let's find out what are those low speeds for which steering works and counter-steering doesn't.
Repeat the #2 procedures, but start moving the bike really slowly, using the clutch.
If you do it slow enough, the bike keeps leaning onto the left side.
Little by little increase that speed, noticing that the tendency to left-lean is less and less as the speed increases.
If you control is fine enough, you will find a speed for which the bike stays vertical while it turns.
That is the critical speed below which steering works.
Why?: The CG of the bike remains left-off the line that joins the contact patches of the front and rear tires, however, the circular movement induces a centrifugal force over the same CG that perfectly compensates for the off-center weight and keeps the bike balanced vertically.


4) Next, let's find out what are the speeds for which steering doesn't work anymore and counter-steering does.
Repeat the #2 procedures but keep both feet down sliding over the pavement, but start moving the bike at about the critical speed that we have just found, using the clutch.
If you do it fast enough, the bike starts leaning onto the right side (careful here, right foot ready to support the bike and hand ready to clutch-in).
Little by little increase that speed, noticing that the tendency to right-lean is more and more as the speed increases.
Why?: The CG of the bike remains left-off the line that joins the contact patches of the front and rear tires, however, the circular movement induces a centrifugal force over the same CG that overcomes the off-center weight and rolls the bike to the right.
That is counter-steering for you, and will work for any speed above that critical speed that we found earlier.


Now, that critical speed will be higher for less dramatic turn angles of the handlebar.

This link explains it better than me:

http://www.tonyfoale.com/Articles/Balance/BALANCE.htm

lnewqban screwed with this post 06-18-2013 at 10:02 AM
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Old 06-18-2013, 07:32 AM   #692
Rucksta
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Quote:
Originally Posted by lnewqban View Post
That is something that anyone can find experimentally:

.
You're right anyone could figure that.
Tony Foale probably figured it long ago and has been struggling explain it since.

What I want to figure is what changes do I make to increase the speed at which steering still works and / or reduce the speed that countersteering kicks in.

I figure trail, fork offset, rake & wheelbase as well as CoG are in play as I've modified those factors chasing other handling characteristics.
A marked change in the steering options available was noticed.
The 15-25 kph range is interesting as I seem to have both types of steering available.

I suspect wheel diameter and tyre width have a bearing on the equation but those are fixed in my application.

Thanks for the tip on speed of turning the bars on the srteering mode test.
I'm probably auto correcting with body & throttle and haven't factored that in as a variable.
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Old 06-18-2013, 08:41 AM   #693
Andyvh1959
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Quote:
Originally Posted by Milosh View Post

You self-aggrandizing "instructors" are trying to teach something anyone on a motorcycle instinctively knows.

Read this: http://www.superbikeplanet.com/2009/Jan/090102b.htm

As "instructors," you might learn something.

But probably not. You're like Health and Safety for Motorcyclists.
Fine, but unless you've spent hours upon hours teaching thousands of newbies and "experienced" riders about it, you can't make a statement like "something anyone on a motorcycle instinctively knows". No way. I have had many students that didn't know squat about how to MAKE a motorcycle handle, much less be instinctive about it. If that were the case we'd have far less than 40% of cycle crashes being a motorcycle crashing on its own, loosing control in a curve, failing to negotiate a cuve, etc. We may know it well, but MOST riders do not.

Oh, and by the way, I do enjoy grinding down the edges of my tucked in riding boots on the curves. Gotta wear off those chicken strips.

But,....I also LOVE agrandizing discussions!!! Because, you know, I AM so self important!!
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Old 06-18-2013, 01:29 PM   #694
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Quote:
Originally Posted by Rucksta View Post
What I want to figure is what changes do I make to increase the speed at which steering still works and / or reduce the speed that countersteering kicks in.
If you are moving on a motorcycle and you turn. You counter-steered in some way... 1 mph or 60 mph.

There is no magic speed when it "kicks in" other than moving/not moving.
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Old 06-18-2013, 03:05 PM   #695
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Oh, and this: http://www.superbikeplanet.com/2009/Jan/090102b.htm

Very true, in respect to highly educated people learning to ride even at the basic level we teach in the MSF. I failed my orthopedic surgeon in the MSF BRC he was in. He's a very intelligent, bright educated man. But he simply would not "accept" the method of countersteering. I finally told him NOT to think it, just DO IT, feel it, and use it. Still would not let his brain accept it, and he failed the class on the swerve and evasive manuevers.

Later I coached him separately and he eventually got his license and is still riding today, ten years later. But, intuitive? For him, no way.
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Old 06-18-2013, 05:29 PM   #696
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Quote:
Originally Posted by Jedl View Post
What is it that causes the bike to lean in the direction you want to turn ?
Who says the bicycle has to lean??? I can do track stands on my bike, remaining motionless. If I can remain motionless and upright, I can go .5, or 2 mph, and remain upright... no lean.

As I said, I aggressively counter steer on my street bike, dirt bike, and supermoto track bike. VERY aggressively. But I believe (and I may be wrong) that you can turn a moto at some very low speed, and not counter steer. Again, I can do track stands on my motorcycle almost as well as I can on my mountain bike, no leaning involved at that speed, same same for .5 mph, 2mph, but I know at 20 mph I am fo sho counter steering. In between is a mystery.

Barry
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Old 06-18-2013, 06:24 PM   #697
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Quote:
Originally Posted by Barry View Post
Who says the bicycle has to lean??? I can do track stands on my bike, remaining motionless. If I can remain motionless and upright, I can go .5, or 2 mph, and remain upright... no lean.

As I said, I aggressively counter steer on my street bike, dirt bike, and supermoto track bike. VERY aggressively. But I believe (and I may be wrong) that you can turn a moto at some very low speed, and not counter steer. Again, I can do track stands on my motorcycle almost as well as I can on my mountain bike, no leaning involved at that speed, same same for .5 mph, 2mph, but I know at 20 mph I am fo sho counter steering. In between is a mystery.
The physics of how the bike or moto operates (balances and steers) is the same irrespective of speed. The two in-line wheels and the geometry define the physics.

What does change with speed are the tactile and visual cues that the rider perceives. You don't feel the effect of angular momentum (the product of the front wheel's moment of inertia and its angular speed) on the steering at slow speeds because those forces are speed dependent. As you go faster (the rotational speed of the wheel increases) the angular momentum increases. As the rotational speed approaches 0.0 mph, the angular momentum approaches zero (0). So the sensation of the steering being stiff at speed goes away as you slow down until the only forces left are everything except the angular momentum of the spinning front wheel. Bicycles always seem to have "lighter" steering because their front wheels have a lower moment of inertia. But if you could get the bicycle going fast enough, you'd feel the same "stiffening" of the steering operating as you do on a moto.

The same is true relative to trail-induced front wheel self-centering because those forces are speed and trail dependent. As the speeds go down the forces approach zero.

As you slow down the required movement of the CoG as well as the angle of lean required for turning are reduced as well. Those requirements are still present they are just very small as the speeds approach zero.

Since countersteering is only about controlling the relative location of the CoG in preparation for a lean into a turn, the sensations that we feel approach zero as the speeds decrease. But the physics remain and are still operating even if we cannot "feel" them at slow speeds.

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Old 06-18-2013, 06:27 PM   #698
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Quote:
Originally Posted by Andyvh1959 View Post
Very true, in respect to highly educated people learning to ride even at the basic level we teach in the MSF. I failed my orthopedic surgeon in the MSF BRC he was in. He's a very intelligent, bright educated man. But he simply would not "accept" the method of countersteering. I finally told him NOT to think it, just DO IT, feel it, and use it. Still would not let his brain accept it, and he failed the class on the swerve and evasive maneuvers.
Of course to attribute the slow learning of physical skills to being highly educated, is equally inaccurate. There are many different and divergent methodologies that various people use for learning something new. Some people rely on a cognitive method that is not based on sensation or physical / body awareness. Often these types of learners find learning by reading and thinking very productive and perform quite well in a purely academic setting. But not so much when they are forced to make sense of how physical sensations relate to real world effects. Education systems often cater to this type of learner and so they are encouraged to continue learning in that system and via that methodology - becoming highly educated in the process.

But that is just one type of learning methodology. The trick to being a good instructor, IMHO, is to assess the student's learning style and deliver the material in a manner that the student can process. Some people learn by doing and talking about it is useless, even counterproductive for them. Others only learn by watching other people perform and nothing but seeing it done will work for them. Other people have to figure it out for themselves and won't even hear the words when someone tries to explain it. There are more types and combinations of learning types than I could list. It's certainly NOT a matter of one-size-fits-all.

cheers,
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Old 06-18-2013, 08:19 PM   #699
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Quote:
Originally Posted by lnewqban View Post
That is something that anyone can find experimentally:

1) From total stop, balance the bike vertically, put both feet up on the pegs.
From that position, if you don't turn the handlebar, the bike will fall to either side.
Repeat and verify: the bike has no preferred side to fall onto.

2) From total stop, balance the bike vertically, put both feet up on the pegs.
From that position, turn handlebar all the way to the left (full lock), the bike will consistently fall to the left side.
Why?: You have moved the CG of the bike left and is now off the line that joins the contact patches of the front and rear tires.
That is steering for you, and will work for standing still and for low speeds.

3) Next, let's find out what are those low speeds for which steering works and counter-steering doesn't.
Repeat the #2 procedures, but start moving the bike really slowly, using the clutch.
If you do it slow enough, the bike keeps leaning onto the left side.
Little by little increase that speed, noticing that the tendency to left-lean is less and less as the speed increases.
If you control is fine enough, you will find a speed for which the bike stays vertical while it turns.
That is the critical speed below which steering works.
Why?: The CG of the bike remains left-off the line that joins the contact patches of the front and rear tires, however, the circular movement induces a centrifugal force over the same CG that perfectly compensates for the off-center weight and keeps the bike balanced vertically.

4) Next, let's find out what are the speeds for which steering doesn't work anymore and counter-steering does.
Repeat the #2 procedures but keep both feet down sliding over the pavement, but start moving the bike at about the critical speed that we have just found, using the clutch.
If you do it fast enough, the bike starts leaning onto the right side (careful here, right foot ready to support the bike and hand ready to clutch-in).
Little by little increase that speed, noticing that the tendency to right-lean is more and more as the speed increases.
Why?: The CG of the bike remains left-off the line that joins the contact patches of the front and rear tires, however, the circular movement induces a centrifugal force over the same CG that overcomes the off-center weight and rolls the bike to the right.
That is counter-steering for you, and will work for any speed above that critical speed that we found earlier.

Now, that critical speed will be higher for less dramatic turn angles of the handlebar.

This link explains it better than me:

http://www.tonyfoale.com/Articles/Balance/BALANCE.htm
Your # 2 is backwards. If you turn left the bike will fall right.
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Old 06-18-2013, 10:26 PM   #700
Rucksta
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Quote:
Originally Posted by joexr View Post
Your # 2 is backwards. If you turn left the bike will fall right.
Did you try it?
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Old 06-18-2013, 10:30 PM   #701
Rucksta
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Congratulations.

Quote:
Originally Posted by DAKEZ View Post
If you are moving on a motorcycle and you turn. You counter-steered in some way... 1 mph or 60 mph.

There is no magic speed when it "kicks in" other than moving/not moving.
This is probably the first time you been wrong in over 18,000 posts.
Almost as good as Supershaft.
Pretty good average.
Well done.
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Old 06-19-2013, 12:04 AM   #702
Dirty in all
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Quote:
Originally Posted by Rucksta View Post
This is probably the first time you been wrong in over 18,000 posts.
Almost as good as Supershaft.
Pretty good average.
Well done.
I think he is speaking from the view of countering the center of gravity which you are always doing regardless of speed in order to balance. If you don't steer to counteract gravity, you will fall.
On the other hand if you look at it from the steering point of view. At one point your were steering in the direction you want to go and at a certain speed you begin to counter-steer in relation to direction.

Might have to give him his gold star back.
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Old 06-19-2013, 06:32 AM   #703
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perhaps an inmate would care to try this experiment i just thought up and report back.
rig a steering stop so the bars will not turn past dead straight in one direction. lets say can turn left only.
next put an electronic protractor on the bike to determine true vertical
have a helper hold the bike true vertical while the rider gets moving.
rider attempts left turn
report back with results
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Old 06-19-2013, 06:33 AM   #704
Rucksta
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Stu beat me to it sort of.

Quote:
Originally Posted by Dirty in all View Post
I think he is speaking from the view of countering the center of gravity which you are always doing regardless of speed in order to balance. If you don't steer to counteract gravity, you will fall.
On the other hand if you look at it from the steering point of view. At one point your were steering in the direction you want to go and at a certain speed you begin to counter-steer in relation to direction.

Might have to give him his gold star back.
There are ways other than / in addition to handlebar input to balance gravity including but not limited body positioning, throttle opening and arc of turn.

Stand beside your bike, left hand on the left grip, right hand on the grab rail and move the bike forward while maintaining full left lock.
No homework or questions to answer just make your own obsevations.

I'm not a big fan of Tony Foale's explainations.
Link is to the a diagram only just in case you've never seen the experiment.

http://www.tonyfoale.com/Articles/Balance/Img00003.gif

Many staunch countersteering sceptics who have held the wheel have an epiphany.
Sometimes you can actually see the penny dropping by the expression on their faces.
Thing is if you spin the wheel really slowly the forces just are not present.

And so the argument goes round and round - just like the bicycle wheel. The faster you spin it the stronger it gets.
To me those who insist countersteering is the only way to turn a motorcyle are missing out on as much as those who instist countersteering is a myth.


Maybe my question belongs in a different thread away from the zealots and sceptics.
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Old 06-19-2013, 06:49 AM   #705
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Quote:
Originally Posted by Rucksta View Post
You're right anyone could figure that.
Tony Foale probably figured it long ago and has been struggling explain it since.

What I want to figure is what changes do I make to increase the speed at which steering still works and / or reduce the speed that countersteering kicks in.

I figure trail, fork offset, rake & wheelbase as well as CoG are in play as I've modified those factors chasing other handling characteristics.
A marked change in the steering options available was noticed.
The 15-25 kph range is interesting as I seem to have both types of steering available.

I suspect wheel diameter and tyre width have a bearing on the equation but those are fixed in my application.

Thanks for the tip on speed of turning the bars on the srteering mode test.
I'm probably auto correcting with body & throttle and haven't factored that in as a variable.
Way, WAY overthinking this.

Countersteering does not make the bike turn. It handles the centrifugal force so you can stay on the bike while it turns. A couple of postings above also make this point. The bike wants to go straight (due to the trail built into the front). If we lean the bike the front end falls into the turn, plus with the bike leaned over we can stay on the seat. If we turn the bike without leaning it, if the centrifugal force is sufficient (product of velocity and radius), we get thrown off the seat and into the weeds. If the centrifugal force is very minor at slow speed we can counteract the centrifugal force with body weight shifts.

As noted above, don't think it. Feel it. Do it. Thinking is slow and tiring. Do it enough hundreds of times that new neural connections are formed in your brain and the movement becomes automatic.
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