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Yesterday, 06:58 AM   #691
lnewqban
Ninjetter

Joined: Jan 2012
Location: Florida
Oddometer: 70

Quote:
 Originally Posted by Rucksta 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 Yesterday at 10:02 AM

Yesterday, 07:32 AM   #692
Rucksta
Chronic Noob

Joined: Oct 2008
Location: Gold Coast
Oddometer: 2,304
Quote:
 Originally Posted by lnewqban 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.
__________________
If the Earth is flat why are my tyres round?

Yesterday, 08:41 AM   #693
Andyvh1959

Joined: Feb 2012
Location: Da frozen tundra, 1.5 mile west of Lambeau
Oddometer: 154
Quote:
 Originally Posted by Milosh 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!!
__________________
When life throws you a curve,.....lean into it!

Andyvh1959 screwed with this post Yesterday at 02:57 PM

Yesterday, 01:29 PM   #694
DAKEZ

Joined: Mar 2007
Location: U-gene, OR.
Oddometer: 18,067
Quote:
 Originally Posted by Rucksta 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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"Be who you are and say what you feel, because those who mind don't matter, and those who matter don't mind."
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 Yesterday, 03:05 PM #695 Andyvh1959 Cheesehead Klompen     Joined: Feb 2012 Location: Da frozen tundra, 1.5 mile west of Lambeau Oddometer: 154 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. __________________ When life throws you a curve,.....lean into it!
Yesterday, 05:29 PM   #696
Barry
Just Beastly

Joined: Oct 2002
Location: Fredericksburg, Va.
Oddometer: 6,482
Quote:
 Originally Posted by Jedl 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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Yesterday, 06:24 PM   #697
Jedl

Joined: Jun 2010
Location: New England
Oddometer: 82
Quote:
 Originally Posted by Barry 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.

cheers

Yesterday, 06:27 PM   #698
Jedl

Joined: Jun 2010
Location: New England
Oddometer: 82
Quote:
 Originally Posted by Andyvh1959 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,

Yesterday, 08:19 PM   #699
joexr

Joined: Jan 2011
Location: Dunedin ,Florida
Oddometer: 1,059
Quote:
 Originally Posted by lnewqban 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.

Yesterday, 10:26 PM   #700
Rucksta
Chronic Noob

Joined: Oct 2008
Location: Gold Coast
Oddometer: 2,304
Quote:
 Originally Posted by joexr Your # 2 is backwards. If you turn left the bike will fall right.
Did you try it?
Static bike!
__________________
If the Earth is flat why are my tyres round?

Yesterday, 10:30 PM   #701
Rucksta
Chronic Noob

Joined: Oct 2008
Location: Gold Coast
Oddometer: 2,304
Congratulations.

Quote:
 Originally Posted by DAKEZ 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.
__________________
If the Earth is flat why are my tyres round?

Today, 12:04 AM   #702
Dirty in all

Joined: Apr 2012
Location: Connecticut
Oddometer: 102
Quote:
 Originally Posted by Rucksta 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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