Talk:Countersteering/Archive 1

Archive 1

Archive 2

Archive 3

Definition

You push in the direction you want to turn. The "counter" part refers to the fact that you are actually turning the handlebar in the opposite direction when you do that, so that is probably what is was intended to say by that change that was made. I remember from the Motorcycle Safety Foundation course that pushing in the direction you want to turn makes it more intuitive and therefore easier to remember. I have corrected the article back to my original and merged counter-steering into this article.Spalding 04:13, Dec 8, 2004 (UTC)

Isn't the first thing to do to clear up the difference between the geometric steering that is used in a car and the force-based steering on a motorcycle/bicycle? I'm going to give that a go. Black bird blue (talk) 11:10, 5 December 2008 (UTC)

I don't think the cleanup tag is justified - between my explanation and the external link, I think it is clearly and logically explained. Spalding 17:10, 4 February 2005 (UTC)

Text from counter-steering article

The following text from User:Manning Bartlett has been copied from the counter-steering article to merge it into this article:

I sat down with all good intentions of writing this article. But as soon as I began to research the various web-pages, I quickly realised that I was out of my depth physics wise.

So here are some links that may benefit a proper physics person to explain this baffling phenomenon. The pages all seem to disagree with each other as to what causes it.

[1] [2] [3] --85.231.166.15 (talk) 20:48, 31 March 2008 (UTC)

Angle vs Camber Angle

I took out camber angle as it is defined as "the angle made by the wheel". While this is true, it is insignifigant in this context. It is the angle of the entire vehicle that matters: specifically the angle made between a horizontal plane and the plane defined by the two wheel contact points and the combined center of mass of the rider and vehicle. AndrewDressel 14:12, 6 June 2006 (UTC)

Language

• Tried to make it sound less like a motorcycle riding school lecture.
• Removed mention of "conventional steering" as it contradicts the assertion that "At low speeds countersteering is equally necessary, but the countersteering is so subtle then that it drowns in the continuous corrections that are made in balancing the bike."
• Softened the distinctions between bicycles and motorcycles and focused more on the increased need to consciously countersteer as speed increases.

AndrewDressel 13:30, 14 June 2006 (UTC)

Walking speed

125.209.173.112 added "above walking pace", but I know of no reason why the physical requirement for countersteering is bounded. Unless someone can find a reference that has shown by physical experiment or some mathematical calculation that countersteering becomes unnecessary, this addition should be reverted. -AndrewDressel 01:37, 23 August 2006 (UTC)

-No reference found, so addition removed. -AndrewDressel 00:37, 25 August 2006 (UTC)

Motorcycles and bicycles are "inverted pendulums" and must be balanced laterally regardless of speed. The fact that many do not notice it at lower speeds is akin to people not noticing how their body balances itself when walking or standing on a line, and then make the leap that it must not exist.

Further, if such a transition speed did exist (say 8mph) where below which one steers and above which one countersteers, no one has stated how the bike is turned AT 8mph, which direction, how quickly (roll rate), and how tightly. — Preceding unsigned comment added by 68.95.127.246 (talk) 07:03, 22 February 2007 (UTC)

Better not give two different explanations for one thing

In the current version of the article it is stated:
"Otherwise the bike and rider's inertia or centrifugal force (depending on your frame of reference) will tip the bike over towards the outside of the curve."
I propose to replace that with:
"Otherwise the bike and rider's inertia will tip the bike over towards the outside of the curve."

The remark about dependency on the frame of reference is unhelpful, I think. It suggests there are two different explanations for the tipping over: either inertia or centrifugal force. But the expression 'centrifugal force' is just a very roundabout way of talking about inertia.

If the bike plus rider fails to lean sufficiently inward, then the center of mass of the bike will follow a less sharp curve than the wheels, and consequently the bike will tip over to the outside of the curve. --Cleonis | Talk 05:53, 25 August 2006 (UTC)

After reading the centrifugal force article, I'd lean towards "Otherwise centrifugal force will tip the bike and rider over towards the outside of the curve." From the point of view of the rider, centrifugal force, psuedo or not, is straight forward and easy to understand. I'd leave the wrangling about inertia to other articles. -AndrewDressel 22:35, 25 August 2006 (UTC)

I favor saying things in a straightforward and consistent way. Don't add unnecessary complexity. Take the example of braking: if a front wheel has a lot of stopping power, a motorcycle may flip over when the rider brakes too hard. The cause of flipping over is twofold: the grip of the front wheel, and the inertia of the motorcycle. It would be very weird to claim that the motorcycle, braking too hard with the front wheel, is flipped over by "the forward force". It's the motorcycle's inertia. The straightforward thing to say about steering into a curve without enough lean is that the danger of flippng over is due to the inertia of the motorcycle. --Cleonis | Talk 00:29, 26 August 2006 (UTC)

Well, there we disagree. In the case of braking, in the initial explanation, it is enough to mention the front wheel's stopping force. In the case of turning, I prefer to mention only centrifugal force. It is the two-word phrase commonly used to represent the effect of inertia of an object in circular motion, as explained in the centrifugal force article. It is especially a concept that "those inside the car will often find natural". -AndrewDressel 02:53, 26 August 2006 (UTC)

If it helps to clarify, the combined mass of the bike+rider will continue in a straight line as the tires' contact points track out and away from under that mass along the curve. Using the term "centrifugal" implies "center-fleeing" and thereby that the rider+bike track along a curve opposite that of the wheels, a common mis-perception that should not be perpetuated no matter how common it is -- that's the point of Wikipedia, no? Inertia does not TIP the bike so much as countersteering TRIPS the bike like pulling the rug out from under one's feet.

I think you are refering to something else. The above discussion was about how to explain why it is necessary to lean in a turn. Your comments appear to be about how that lean is initiated. -AndrewDressel 02:38, 22 March 2007 (UTC)

Very low speed

I have removed the sentence "So at very slow speeds, the bike can be steered while completely upright like a car, involving no countersteering." added by 82.47.85.24

The assertion of "completely upright" is simply wrong because by being in a turn at all, a bike and its rider will experience centrifugul force that must be counteracted by leaning. There are no exceptions.

That the lean angle is very small or that the handlebars are turned far in the direction of the desired turn does not mean that the momentary countersteering necessary to initiate that lean can be skipped. -AndrewDressel 14:52, 3 October 2006 (UTC)

I'm a farily experienced (motor)bike rider, and at very low speed, say walking pace, you do not countersteer (or at least it's optional), even to lean. Dave 04:23, 28 October 2006 (UTC)

How then do you create the necessary lean? -AndrewDressel 03:13, 29 October 2006 (UTC)

At the lowest speeds, you don't lean. Dave 17:01, 29 October 2006 (UTC)

Then how do you counter the Centrifugal force? -AndrewDressel 19:54, 29 October 2006 (UTC)

I don't see why it needs countering - tyre sidewalls should surely take it, as far as I know there's no reason why resultant force on the bike need be vertical (with respect to the bike). Dave

The reason the resultant force (sum of all forces) needs to be vertical with respect to the the bike (exactly coincident with the plane defined by the two wheel contact points and the combined center of mass of the bike and rider) is to keep the bike from falling over. I don't know what you mean by "tyre sidewalls should surely take it." -AndrewDressel 22:01, 29 October 2006 (UTC)

On reflection, as counter intuitive as it seems you must be right, as I can't see any other way there wouldn't be a resultant moment around the centre of mass. Dave 13:34, 30 October 2006 (UTC)

I think what trips us all up is how at lower and lower speeds the necessary but decreasing countersteering becomes overwhelmed by growing adjustments required simply to maintain balance. We are able to unconsciously take advantage of random, minute leans in the desired direction. I guess one could argue, in that case, that conscious countersteering becomes unnecessary. However, in the ideal case of well maintained balance, as I argued with you, there is not a point at which all countersteering become unnecessary. -AndrewDressel 18:21, 31 October 2006 (UTC)

Very simply, a bike is an "inverted pendulum" which must be balanced laterally (side to side) regardless of speed. Personally, I easily have over 200,000 miles on motorcycles on various surfaces (paved, dirt, gravel, grass, snow, ice), won numerous slow races (>1mph races where the goal is to be the LAST one to cross the finish line with out leaving your narrow lane nor putting a foot down) and also teach motorcycle classes.

When executing a tight U-turn from a straight line on level ground in fresh snow at dead slow speeds (due to the vey limited traction), the evidence of countersteering can still be seen in the tracks where the front wheel always tracks first to the side of the straight line AWAY from the desired direction of turn. This can also be done with wet tires on dry pavement and the use of a chalk line snapped onto the ground. Though the amount of countersteering decreases with slower speeds and wider turns, it remains present though often overlooked.

—Preceding unsigned comment added by 68.95.127.246 (talk • contribs) 08:13, 22 February 2007 (UTC)

(above)I think you are confusing tracking with counter steering. Counter steering is an input function with a physical explination. What you describe about slow turns would apply to all vehicles would it not?

Also to say a bike is an inverted pendulum relates directly to the speed, as soon as a bike moves it no longer acts like a pendulum at all. —Preceding unsigned comment added by Bennett366 (talk • contribs) 03:59, 16 April 2008 (UTC)

Track is proof of countersteering. If the front tire track goes right before turning left, it is because the bike was steered to the right before turning left. Three and four wheeled vehicles have no need to lean in a turn and so have no need for the front wheel(s) to track to the opposite direction in order to create that lean before steering in the direction of the turn.

All that happens when a bike moves is that the pivot point of the inverted pendulum can now be moved in order to keep the pendulum in balance. Gravity still pulls it in the direction it leans. -AndrewDressel (talk) 13:49, 16 April 2008 (UTC)

There is a "very low speed" control regime described by Robinson ("Motorcycle Tuning: Chassis") in which large steer inputs rotate the whole machine in the direction of the turn due to the trail in the steering geometry. For these inputs the CG is no longer above a line joining the two contact patches. The resulting roll moment can be shown to balance a very low speed turn. This effect is one of several mountain bike riders use to balance when performing "track stands". It is also, however, utterly trivial and vanishes above walking pace. See also SAE 950199 : "A Servo Rider for the Automatic and Remote Path Control of a Motorcycle". Black bird blue (talk) 12:54, 5 December 2008 (UTC)

Possible inter-Wiki Link

This technique is also used in 4 wheel motorsport but is termed "Scandinavian flick". Perhaps a link to the Wiki article would be relevant? 203.46.95.243 00:55, 13 February 2007 (UTC)

The only thing in common between the two is the momentary turn in the opposite direction. It doesn't appear to be for the same reason or work in the same way. Is it ever refered to by the same name? Otherwise, I'd say a link would not be relevant. -AndrewDressel 05:03, 13 February 2007 (UTC)

Hello Andrew. I've mentioned in the "Scandinavian Flick" page that perhaps it should be mentioned or merged into the "Opposite Lock" page. I have had the term "Scandinavian Flick" used by a motorcycle instructor trying to explain the countersteering concept to me, as I do 4-wheel motorsport, but I can see your point: "Opposite Lock" page link is much more appropriate here. Thanks for the suggestion. 203.46.95.243 01:37, 19 February 2007 (UTC)

Fascinating bit of OR

This article is clear, lucid, well referenced, and just plain wrong. While no-one denies that countersteering does work, it is not a necessary, and not even a normal, technique for steering a light bike at any speed, and, indeed, it becomes easier to steer without countersteering as speed increases. This is easily demonstrated by experiment.

Take any bicycle. Tie a piece of string from the seat post to the extremity of one handlebar, so that the steering can be straight or can turn to that side, but not even slightly to the other side. Ride the bike. If countersteering were necessary, the bike would be unridable. However, it is perfectly easy to ride - but you must eventually turn to the side where the string is. That turn is initiated without counter-steering, since counter-steering is not possible.

The normal technique for steering any light bicycle at more or less any speed above walking speed is to move the pelvis to one side while moving the shoulders to the other. This initiates a lean of the bicycle, which automatically turns into the lean. No countersteering is required. Simon Brooke 10:30, 20 February 2007 (UTC)

Just two questions:

1) Can you cite any reputable source for this claim?

2) In the expiriment you describe, how is the system center of mass leaned to the inside of the turn? Moving the hips one way and the sholders another merely lowers the center of mass. Wilson and Papadopoulos, in the 3rd edition of Bicycling Science state categorically that for the leftward lean necessary for a leftward turn "the support point must first move to the right of the system center of mass to create the lean." (Emphasis added by original authors). With the steering prevented from turning right, how can the support point move to the right? If I had to guess, I'd say that, especially at slow speeds, a very small turn is necessary, and a string tied between the seat and handle bar is insufficiently stiff to prevent such a small turn.

-AndrewDressel 15:08, 20 February 2007 (UTC)

Guess not. -AndrewDressel 18:05, 22 February 2007 (UTC)

Okay, since Simon Brooke appears to have gone missing, or cannot answer either of my two questions and won't say so, I would like to make it perfectly clear to anyone who might stumble upon this discussion. His claim above that this article (as it appears on March 1, 2007) as being "just plain wrong", is completely bogus. He will not be able to find a reputable source to back up his claim because one does not exist. His described experiment is completely refuted by the published work of David Jones (Physics Today, 1970) "the ridability of a bicycle depends crucially on the freedom of the front forks to swivel". Brooke's explanation completely misses the point of the need to move the combined center of mass and suggests a grave misunderstanding of basic physics and mechanics. -AndrewDressel 15:20, 1 March 2007 (UTC)

Countersteering when riding no-hands

I can turn shallow corners on my bike, then straighten up, without having my hands on the handlebars. How do I manage unconscious countersteering? 125.236.197.192 00:30, 11 October 2007 (UTC)

But can anyone do anything meaningful with no hands? Actually negotiate a defined path, rather than just wobble along a wide road? God, this is all so maddening it's untrue. Black bird blue (talk) 12:57, 5 December 2008 (UTC)

Good question. The article should address this point.

The way countersteering can work when riding no-hands goes like this. In order to turn left, apply a momentary torque, either at the seat via the legs or in the torso that causes the bike itself to lean to the right. The combined center of mass of the bike and rider is only lowered, of course. However, if the front of the bike is free to swivel about its steering axis, the lean to the right will cause it to steer to the right by some combination of gyroscopic precession, ground reaction forces, gravitational force on an off-axis center of mass, or simply the inertia of an off-axis center of mass, depending on the exact geometry and mass distribution of the particular bike, and the amount of torque and the speed at which it is applied.

This countersteering to the right causes the ground contact to move to the right of the center of mass, as the bike moves forward, thus generating a leftward lean. Finally the front end steers to the left and the bike enters the left turn. The amount of leftward steering necessary to balance the leftward lean appropriate for the forward speed and radius of the turn is controlled by the torque generated by the rider, again either at the seat or in the torso.

To straighten back out of the turn, simply reverse the procedure for entering it: cause the bike to lean farther to the left; this causes it to steer farther to the left which moves the wheel contact patches farther to the left, eventually reducing the leftward lean and exiting the turn.

The reason this no-hands steering is less effective on heavy bikes, such as motorcycles, is that the rider weighs so much less than the bike that leaning the torso with respect to the bike does not cause the bike to lean far enough to generate anything but the shallowest turns. Riders may be able to keep a bike centered in a lane and negotiate shallow highway turns, but not much else. -AndrewDressel 13:55, 12 October 2007 (UTC)

No-hands steering

While there is documented physical experimentation showing that leaning a motorcycle is ineffective for steering, it is well known that bicycles can be steered quite effectively by leaning and without touching the handlebars. See "Bicycling Science" the third edition by Wilson for a brief explanation. -AndrewDressel 14:24, 3 April 2007 (UTC)

Suggested Addition to Introduction

I think it should be made more clear in the introductory paragraph that countersteering is a technique that is learned intuitively rather than theoretically. Considering the phenomenon exclusively in its physics based components is going to give people the wrong idea that countersteering is something that needs to be consciously mastered.

Something became clear to me in a physics course, where simple actions like throwing a baseball were deconstructed into its basic physical components - eventually turning a familiar act into unintuitive mathematical concepts. To me, it proves how great the human mind acts as a subconcious calculator. Humans can apply conscious thought into perfecting a physical task, but success ultimately relies on teaching the subconscious, through pratice and human intuition.

People, especially motorcyclists, like to make countersteering into something greater than it is. It's great that the article explains the concept in detail, but I think without an explicit disclaimer it is going to give people the wrong idea. It did for me when I first came across the concept, until I learned its realistic application to single track vehicles from someone more grounded. LostCause 11:23, 23 August 2007 (UTC)

Quote: ...countersteering is a technique that is learned intuitively rather than theoretically.

Not true. The MSF motorcycling course explicitly teaches countersteering and in my experience it has to be consciously practiced and mastered. The more intuitive approach to motorcycle cornering is to just 'lean' the bike with body english (some people push with their thighs or lean their torsos over); countersteering, however, is far more efficient (in terms of speed and body movement) aa well as more effective. --Bk0 (Talk) 12:30, 23 August 2007 (UTC)

The only way to make a bike turn????

Before I make a change and have it removed: "the only way a rider can cause a single-track vehicle to turn" This seems to be a point of contention however this is untrue. At anything like a reasonable speed (say 10mph or above) countersteering is how you steer, I certainly agree. However during low speed manovers you steer as you would expect, push on the left handlebar and you turn right, the tyres behave as in a car.

The difference is the lean angle, because at low speed you do not lean the contact patch doesn't move therefore the countersteering does not occur. If you lean during slow manovers you will lose balance and drop the bike. Is it worth producing a video to demonstrate this? Rufty 22:45, 13 September 2007 (UTC)

If it were true that "at low speed you do not lean", then by what other means do you balance the centrifugal force (or inertia, if you prefer) due to the turn, and what calculation can you use to determine at what speed leaning become unnecessary? The equation currently provided in the article produces a non-zero lean angle for any non-zero forward speed. I don't believe a video would help. At low speed, the lean angle is small and difficult to see. The fact that you eventually steer in the direction of the turn does not contradict the fact that you countersteered to initiate the turn. -AndrewDressel 13:24, 11 October 2007 (UTC)

I don't know the maths, I can only perform the experiments. I usually trust experimental proof over mathematical proof, but then people would argue I'm not an impartial observer and that original research isn't allowed on wikipedia ;-) I only know that at approx walking pace I turn the handlebars in the direction I want to go, and much above that I counter steer(turn opposite to the direction I want to go).

Again I have experienced that counter-steering comes into effect at lower speeds on my motorbike than on my push-bike.

I'm sure anyone who has ridden a bike has experienced that it is easier to maintain balance when going faster. There is no clear point when the rider is controlling the balance (as at slow speeds) and when the bike itself is doing the balancing (as at high speeds). If I understand the physics correctly it is this self balancing/uprighting effect that makes countersteering necessary. Therefore the need for countersteering goes away when it is the rider who is providing the balance control.

I don't disagree that countersteering is the major force at a significant speed, however I do insist that at low speeds where the lean angle is not significant, that the lean required for countersteering means that the more traditional - turn the tire the way you want it to go - is the required solution.

Every where else I investigate countersteering it discusses countersteering taking over from between 5mph and 20mph e.g.:

http://www.survivalskills.clara.net/riding_skills_10.htm

http://www.msgroup.org/TIP048.html

Note the tire does turn in the direction of the turn on http://uk.youtube.com/watch?v=OLzB5oriblk

From http://www.ottawamotorcycle.ca/totm24ctsr.shtml "turn the handlebars left, and the bike leans right, and then goes right. So the bike goes in the opposite direction to the turn of the handlebars", it then goes on to say, "At very slow speeds (creeping into a parking space, slipping the clutch in 1st gear) the amount of lean induced by the handlebars is not significant, and motorcycles steer like tricycles. ". Now re-watch the above video, when the handlebars are turned right, at low speed he does turn right. Repeat it at high speed and the other effect noticed in the video, that turning to the right causes the bike to lean to the left and you will turn to the left.

So unfortunately I can't provide the maths, but I can provide the experiments to preform for yourself (ride any bicycle at low speed), multiple independent documented evidence and an explanation.Rufty 17:32, 24 October 2007 (UTC)

If steering is so geometric at low speed, why on earth did it take so long for you to learn to ride a bicycle as a child? Really, this stuff about "I don't trust maths" wears very thin. If you don't trust maths then read and understand some of the extensive experimentation that has been done on the topic. Balancing a bike is simply an inverted pendulum problem. Black bird blue (talk) 13:19, 5 December 2008 (UTC)

I believe the problem is in confusing countersteering, used only briefly to initiate or alter a turn, with the torque and steering angle required during the rest of the turn. In a sharp turn at low speed, the brief countersteer is miniscule compared to the large steer angle in the direction of the turn necessary for the remainder of the turn. The fact that there is a large steering angle in the direction of the turn does not mean that countersteering did not occur at the begining. The fact that the bike does not fall over during the turn, no matter how slow, means that the bike is leaning into the turn, and the only way to make that happen without some outside influcence is to countersteer. The sources you quote say lean is "not significant", but they do not say it is not present. The article already says "although at low speeds it can be lost or hidden in the minute corrections made to maintain balance."

The statements "it is this self balancing/uprighting effect that makes countersteering necessary. Therefore the need for countersteering goes away when it is the rider who is providing the balance control." Are not correct. The need to lean the bike into a turn so that it doesn't fall over toward the outside of the turn is what makes countersteering necessary. Therefore countersteering is necessary no matter how balance control is implemented. -AndrewDressel 18:57, 24 October 2007 (UTC)

Steering no hands, alternate explanation

<Alternate theory removed, since there seems to be ample evidence that it was wrong!>

A couple of points:

1. There already are two references in the steering no hands section: Steering in bicycles and motorcycles by J. Fajans, published in Am. J. Phys., Vol. 68, No. 7, July 2000 and What keeps the bicycle upright? by Jobst Brandt, published on SheldonBrown.com. Both agree that when riding no-hands "the bicycle must be leaned away from the preferred lean angle and direction of a curve so that the turn can be initiated."
2. I suspect the flaw in the above theory is that the small, momentary sideways force a rider is able to generate with their feet is overwelmed by other factors such as the weight of the rider which, when combined with the mechanical trail of the front wheel, results in a torque on the front wheel in the direction that the bike leans; and gyroscopic precession of the front wheel which also results in a torque on the front wheel in the direction that the bike leans.

I hope this helps. -AndrewDressel (talk) 14:37, 30 March 2008 (UTC)

Thanks for the very quick feedback! Well, I would very much like to read those references, but the links are dead. You don't happen to know if they're hosted somewhere else as well?

I still don't understand why you have to start _leaning_ to the right in order to go left. Steering to the right, I can understand. But not leaning. But of course, me being unable to understand it, doesn't mean it's wrong :-). In fact, if there are solid references to the lean-right-first-to-go-left school, I'm willing to accept bicycles being even more complex than I thought :-) --Avl (talk) 20:49, 31 March 2008 (UTC)

I found one of the references: http://ihpv.free.fr/myihpv/pdf/SteerBikeAJP.pdf . It seems I was totally wrong! :-)

Sorry about the broken links, I formated them incorrectly when I pasted them above. I fixed them, just tested them, and they both work now. Yes, bikes are quite tricky. -AndrewDressel (talk) 21:16, 31 March 2008 (UTC)

Is a counter-steer really necessary to turn a bike?

Everyone seems to agree that in order to maintain course on a bike, as the bike tends to fall/lean to one side or the other, a subtle steer in the direction of each fall/lean is required to straighten it up (bring it back into balance). Presumably, if the rider over-corrects, the bike will go beyond the balance point and begin to fall to the other side, while if the rider under-corrects, the bike will approach the balance point but will remain just this side of it, and will again begin to fall/lean to the same side. In theory, a very precise cyclist should be able to maintain course by only using corrective steering to one side, by never correcting so much that the bike begins to fall/lean in the opposite direction. This is why it is so difficult, but at least theoretically possible, to ride a bike next to a curb. If the curb is on the cyclist's right, as long as it always falls/leans to the left, the cyclist only has to turn away from the curb -- but not too much -- to bring the bike (almost) upright, until it begins to fall to the left again. I suppose multiple corrections to the left, and none to the right, will cause the bike to move away from the curb, but it should work for a while.

With the above in mind, consider a ridden bike (not next to a curb this time) falling to the left repeatedly, and being corrected/uprighted/balanced repeatedly by turning to the left (but again not quite enough to bring it beyond the brink of balance so that a corrective steer to the right would be required). To turn this bike left, the bike must first lean left. The article claims that the only way to do this is to counter-steer right. But isn't it possible to just let this bike fall/lean to the left without correcting it, before turning into the turn? If so, where is the counter-steer? It's not there, neither from a push of the hands nor a shift in the hips.

In other words, one should be able to even take a 1,000+ lbs Harley in an empty parking lot, ride it in a straight line, and, when it starts to fall to one side or the other, instead of immediately turning into the fall to correct it, wait a moment until the lean is far enough down to make a good turn, then turn into the fall. Presto, a turn without a counter-steer. What am I missing?

You're missing that in general we try and follow a specific path. Black bird blue (talk) 13:26, 5 December 2008 (UTC)

This is not just idle theoretical pondering. I am convinced I often get my lean not by counter-steering, but by simply not correcting for a natural fall that happens to be going in the desired direction, and allowing the fall to continue so that I have the lean desired for my turn, then turning into it. One might argue that the last "corrective steer" must have been in the opposite direction, and that's my counter-steer, but I would argue that it's just as likely that my last corrective steer was in the same direction of the desired turn, but just wasn't quite enough to bring the bike past the brink of balance, so that it again fell to the same side.

I don't really care what you are convinced about. Your convictions disagree with a body of peer-reviewed literature. Get over it. Black bird blue (talk) 13:26, 5 December 2008 (UTC)

So while I definitely agree that an initial lean to a given side is required in order to be able to turn a bike in that same direction and maintain its balance against centrifugal forces through the turn, and that a counter-steer is probably the most effective way to produce a lean in the desired direction, I don't see why a counter-steer is necessarily required to initiate a lean. When appropriate, it seems to me that skipping a subtle corrective steer in the same direction, without counter-steering, will produce the same result. --Serge (talk) 06:48, 5 August 2008 (UTC)

This would only be possible at "low" speed, where the maximum speed value is determined by the bike's geometry and mass distribution. Otherwise the bike itself will steer to correct for the lean.

I guess the current text

because there is no other way to cause the bike and rider to lean short of some outside influence such as an opportune side wind, although at low speeds it can be lost or hidden in the minute corrections made to maintain balance.

could be tweaked like this

because there is no other way to cause the bike and rider to lean short of some outside influence such as an opportune side wind, although at low speeds it can be lost or hidden in the minute corrections made to maintain balance or the rider can simply wait until the bike starts to lean in the desired direction because of some random perturbation.

-AndrewDressel (talk) 12:28, 5 August 2008 (UTC)

I understand that when I give an unmounted bike a good push by the saddle, it steers itself for a while, until it slows down. But how does a bike with handlebars controlled by the rider's hands and arms steer itself? A rider does not merely influence the turning of the bars/wheel and thus the steering of the bike, he controls it. The self-steering torque of a 20 lbs bike is negligible compared to the torque applied by the rider (which is why bikes with no rake that do not self-steer are just as easy to ride/balance). Sure, you can choose to let go and allow the bike to steer itself, but nothing requires the rider to relinquish this control. Since a rider can control which way the bike leans and how much, and whether it maintains or changes course, I don't see why the rider cannot control the lean of CM such that it remains to one side or the other of "ideally balanced".

Yet again, the control of a motorcycle is not achieved by positionally controlling the handlebars. Black bird blue (talk) 13:26, 5 December 2008 (UTC)

And even if such side-biased control were not possible, there is nothing to prevent the rider from neglecting to correct for the next fall/lean, allowing it to fall/lean far enough to sustain a turn in that direction when he eventually turns the bars in that direction, without any counter-steer. An explicit counter-steer is not necessarily required to initiate the lean required to turn a bike (or even a heavy motorcycle). I think the article should be clear on this point. --Serge (talk) 18:34, 5 August 2008 (UTC)

1. If the rider is on the bike, then the rider's mass must be included with that of the bike, and it generates a lot more torque, via the lever arm of trail, than just the bike alone.

2. It is completely unclear how precisely a rider controls the position of the handlebars, especially when a turn of less then a degree is significant. The handlebars are at 'arms length' and the torque applied by the bike is continuously changing and invisible.

It's not at all unclear. The steering degree-of-freedom is free - it is not position-controlled. The rider applies a biasing torque to it. The Evangelou PhD and everything by Sharp all testify to the same thing. If we can stop endlessly referring to internet sources that lack credibility and go back a couple of decades to properly peer-reviewed stuff there is loads of it all in agreement. The motorcycle is an inverted pendulum with roll acceleration being applied via steering torque with a negative gain. Why all this agony? Black bird blue (talk) 13:33, 5 December 2008 (UTC)

Well, welcome to the discussion. I won't try to respond to all your recent posts, but I find this one interesting. I don't know what internet sources you are referring to, but I try to get the most I can out of Cossalter and Wilson's books, and the paper in the Proceedings of the Royal Society. Besides the actual experiment showing that gyroscopic forces are unnecessary and the notoriety it got from being published in Physics Today, Jones' article, that you mention elsewhere, isn't very helpful because it is "based on qualitative dynamics discussions that are too reduced to capture the ability of an uncontrolled moving bicycle to balance itself." Evangelou is already cited in the Bicycle and motorcycle dynamics article. Some of your comments appear to be in response to very old comments. I like your point about bikes being force controlled instead of position controlled. Perhaps we could pick one place to continue and move all these related articles forward. How about on the Bicycle and motorcycle dynamics talk page? -AndrewDressel (talk) 15:13, 5 December 2008 (UTC)

3. If you can provide a reliable source to cite, by all means, let's get it into the article.

-AndrewDressel (talk) 19:01, 5 August 2008 (UTC)

The fact that a bike that does not self-steer can never-the-less be easily steered/controlled/balanced by the rider is already cited and established. Therefore the effect of the self-steering torque on a bike that does self-steer cannot be that significant, and is definitely not at all significant on a bike that does not self-steer. What needs to be sourced is not this, but the claim made in the second sentence of the article: "[Countersteering] is the only way a rider can cause the lean that a single-track vehicle must have in order to negotiate a turn successfully." Can you provide a reliable source to cite to support that assertion? --Serge (talk) 21:44, 5 August 2008 (UTC)

Wilson, in Bicycling Science, says "the support point must first move to the right of the system center of mass to create the [leftward] lean." The emphasis is Wilson's. Fajans, in Am. J. Phys., Vol. 68, No. 7, July 2000, says essentially the same thing, but he doesn't call countersteering when it is done no-handed. Cossalter, in Motorcycle Dynamics, uses "countersteering" to mean something else, hence the short section at the end of the article on other uses, but illustrates "you turn left to go right". I cannot find any author that provides an alternate method for generating the lean required to negotiate a turn. -AndrewDressel (talk) 22:08, 5 August 2008 (UTC)

No one disputes that if, from a normal upright maintaining-course position, you briefly turn the bars left, the bike will immediately begin to turn left, but also will make the CM lean right, and then you have to steer right (or allow it to self-steer right), and thus turn the bike right, to keep it from falling over. Therefore "you turn left to go right". That doesn't mean the only way to induce that lean is with a counter-steer. The point is that if the CM begins to tend to the right of balanced for some reason other than a counter-steer to the left, that lean to the right is just as useful for the right turn as is one induced by a counter-steer to the left. That is, there is nothing magic about a lean induced by a counter-steer, and it is the lean that is essential to making a successful turn, not the counter-steer.

I wouldn't have a problem with the article pointing out that briefly steering in the direction counter to the intended turn is the most common, most practical, most precise, etc., way to induce the lean required to successfully execute a turn, soon followed by steering into the lean/turn, but I have a problem with the absolute wording, "the only way".

Imagine pushing off on a bike with the headset locked in the straight-ahead position so that it cannot be steered. You might be able to ride it for a few feet, maybe, but very soon you would helplessly fall, right? Now imagine that the headset is not totally locked, but only locked from turning left of straight-ahead; the bars can only be turned to the right (and back to straight-ahead). Can this bike be ridden round and round in right-hand circles in an empty parking lot, or not? I submit it can be ridden not only in circles, but in oval-like figures where you're going almost perfectly straight along the long stretches. This is a bike that would be prevented by design from counter-steering left of straight-ahead, yet could be made to turn right (by steering right) all day long. Hence, turning (right) without counter-steering (to the left of straight-ahead) must be possible. I wish I had a study to cite for this, but I just thought of it myself. --Serge (talk) 23:20, 5 August 2008 (UTC)

The article already states "It is the only way a rider can cause the lean" and "there is no other way to cause the bike and rider to lean short of some outside influence such as an opportune side wind". Perhaps you want to enumerate other outside influences. It may be a matter of semantics, but I don't consider "waiting until some outside influence leans the bike in the desired direction" as a way for "a rider to lean the bike in the direction of the intended turn."

I don't see what you are trying to show with your example. Increasing or decreasing the radius of a turn by countersteering is already described in the article in the section titled Adjusting or exiting a turn. Countersteering "to the right" in order to increase the leftward lean once already in a left turn doesn't mean "to the right of straight ahead". It means "to the right of the steering angle necessary to maintain the original steady-state left turn" which could certainly be to the left of straight ahead. However, the moment your example bike becomes vertical, it has a 50/50 chance of falling uncontrollably to the left. -AndrewDressel (talk) 02:56, 6 August 2008 (UTC)

Exactly! Even if the bike becomes vertical (balanced equally side-to-side), the chance is still 50/50 that it might lean/fall to the right, even with no countersteer to the left. So, there is a 50/50 chance that no countersteer to the left is required to initiate the lean/fall to the right in order to turn the bike to the right! Therefore, a counter-steer is not necessarily required to cause the lean that a bike must have to negotiate a turn successfully. This is especially true if the cyclist manages to keep the bike from going fully vertical, but remaining slightly biased to the right, following, say, the circumference of a circle with a hundred mile radius. So, the claim made in the second sentence of the article, that "[countersteering] is the only way a rider can cause the lean that a single-track vehicle must have in order to negotiate a turn successfully" is nonsense. Maybe it's the only reliable/precise way, but luck of the 50/50 draw is another way to cause the lean that a bike must have to negotiate a turn successfully. I, for one, believe I happen to use this technique unconsciously about (not coincidentally) half the time I need to turn. --Serge (talk) 03:29, 6 August 2008 (UTC)

It appears that you and I have different definitions of the word cause. I use it as a verb to mean make something happen. I do not consider waiting for a 50/50 chance of something to happen to be causing that thing to happen. When I flip a coin that I hope comes up heads, I don't say that I caused it to come up heads if it does. Do you? -AndrewDressel (talk) 14:19, 6 August 2008 (UTC)

Ah, I see your point. Well, first of all, cause does not necessarily imply intent. One may inadvertently cause something, for example. Secondly, a bike is constantly on the verge of falling one way or the other, and thus the cyclist is constantly engaged in making minor corrective steers, one way or the other. So it's not a matter of waiting for something to happen. Every moment you unconsciously know whether you need to correct to the left or the right (in order to maintain course/balance). If at a given moment when you want to initiate a lean for a right turn you also sense it's a moment to correct for a lean beginning to the left, then you go ahead and correct for the left lean (thus initiating a lean to the right - with a counter-steer to the left). But it's just as likely that at the moment you need to initiate a lean to the right you also sense it would be time to make a corrective steer to the right if your intent would be to continue maintaining course and upright balance (because of your sense that the bike is starting to lean to the right). So you simply omit making that corrective steer to the right, thus causing the lean needed for the right turn by not doing anything to nip the right lean in the bud, if you will, but in any case you're not counter-steering to the left and yet causing (making it happen) the initiation of the lean to the right required to make the upcoming steer/turn to the right. --Serge (talk) 04:29, 7 August 2008 (UTC)

One last point (well, we'll see, won't we.) The bike is constantly on the verge of falling one way or the other only at "low" speed. Once it is moving at a speed in its stable range, if such a range exists, or higher, the bike is quite actively correcting for any lean by itself. In fact, I would argue, though I do not have a source, that the bike will be better at it than any rider could be because it does not suffer from the delayed response that the rider cannot avoid (detect lean, formulate response, transmit signal to muscles, etc.). -AndrewDressel (talk) 13:58, 7 August 2008 (UTC)

Again, I think it's established fact that a bike without the rake to self-steer is still easy to ride/steer/balance, so I think that's grounds to dismiss the significance of the self-steering effect. I'd love to see a 180 lbs weight (like a sack of sand) attached -- balanced laterally -- to the top of the saddle of a road bike that is pushed up to 20 mph and released. Do you really think the bike will sustain balance and maintain course until it slows to a speed below its stable range? That's hard to imagine (but I'd like to see it actually tested). I think the rider's input - though unconscious - correcting for leans initiated to one side or the other is almost constant. Surely you've observed other riders that you ride with often... don't you agree that the way the bike behaves is much more a function of the rider than the bike geometry? Some riders are constantly over-correcting in each direction, resulting in a distinctive track of repeated S's, while others are rock-solid-straight and appear to be riding on an invisible rail, and this is the case no matter which bike these riders ride, and when the speed is well into the bikes' "stable range". Now, note that here I'm talking about bicycles - where the rider's top-heavy weight is a significant factor in creating a high center of mass, as opposed to a motorcycle where the center of mass is much lower and the bike/rider weight ratio is much higher (say 4:1 vs. 1:8). So, yeah, I bet a motorcycle propelling itself at 20 mph with a 180 lbs weight might be able to maintain balance and course for quite a while, but not a 16 lbs road bike with narrow tires and 180 lbs top-heavy mass... food for thought... Oh, and as to the rider's "delayed response" (compared to the bike's), I think the unconscious mind - which is what balances a bike and makes the corrections - can be very quick. This is exactly what it learns to do when one learns to "ride a bike" (as a matter of fact, if the bike's self-steering was more significant than constant rider corrective input, then there would be very little for the unconscious mind to learn when learning to ride a bike once the bike is moving more than a few mph - into the "stable range" - which is not the case). I think you might be conflating the corrective steering input that a rider unconsciously constantly provides (whether directly while riding hands-on or indirectly when riding "no hands") with the bike "self-steering" due to its geometry. --Serge (talk) 18:02, 7 August 2008 (UTC)

Proposed change to first paragraph

Currently the first paragraph is as follows:

Countersteering is the name given to the counter-intuitive technique used by cyclists and motorcyclists to turn corners. It is the only way a rider can cause the lean that a single-track vehicle must have in order to negotiate a turn successfully.

What I propose it states instead:

Countersteering is the technique used by cyclists and motorcyclists to initiate the process of turning toward a given direction by first steering to the side counter to the desired direction ("steer left to turn right"). In order to negotiate a turn successfully, the center of mass of the rider and his single-track vehicle must be leaned to the side in the direction of the turn, and a steer to the opposite side causes a lean in the desired direction. Once sufficient lean is established to sustain the desired turn, the rider then steers into the turn to actually cause the bike to turn in the desired direction.

The main reason I propose this is to clearly define the meaning of countersteer in the first paragraph, which I believe this does. I think it's also important to make clear very early in the article that the countersteer alone does not cause the bike to turn, but that a steer in the direction of the turn is also required (once the lean is established). I also want to avoid the "only way to cause" language for the reasons I explained in the previous section.

Are there any objections or recommended modifications to this proposed change? Thanks. --Serge (talk) 05:04, 7 August 2008 (UTC)

I suggest these slight tweaks:

Countersteering is the technique used by cyclists and motorcyclists to initiate turning toward a given direction by first steering counter to the desired direction ("steer left to turn right"). In order to negotiate a turn successfully, the combined center of mass of the rider and the single-track vehicle must first be leaned in the direction of the turn, and steering momentarily in the opposite direction causes that lean. Once sufficient lean is established to sustain the desired turn, the rider, or in many cases the bike itself, then steers into the turn to cause the bike to turn in the desired direction and stop the lean from increasing.

I tried to simplify the language by leaving out some phrases that I don't think are necessary. I added mention that steering in the direction of the turn may just as well be done by the bike, as the graphs I've added demonstrate. It appears that we leave open the option of taking advantage of 50/50 chance discussed above at length. I guess given the lack of sources either way, that is the best option for now. If this works for you, go ahead and put it in. -AndrewDressel (talk) 13:50, 7 August 2008 (UTC)

I like your changes. Thanks. Done. --Serge (talk) 18:07, 7 August 2008 (UTC)

More on necessary countersteer: 2nd Paragraph...and 'Need to lean to turn'

Sentences in both these locations still indicate that countersteer is necessary to cause a lean. The above lengthy discussions not withstanding, I believe this is false.

I'll be embarrassed if I'm wrong here, but it seems an element of physics that shows how countersteer is not the only (non-trivial) way to initiate a lean in a 2-wheeled vehicle has been forgotten. Namely, friction between the bike tires and the ground.

Problems in article:

2nd paragraph: "The physical phenomenon always occurs, because there is no other way to cause the bike and rider to lean short of some outside influence such as an opportune side wind, ..."

Need to lean to turn subsection: "The transition of riding in a straight line to negotiating a turn is a process of leaning the bike into the turn, and the only way to cause that lean (of the combined center of mass of bike and rider) is to move the support points in the opposite direction first.[3] The rider can shift his weight of course, but any force used to move one way laterally pushes the bike laterally the opposite direction with equal force. That makes the bike lean (and can affect the steering), but it does not change the combined center of mass of bike and rider."

Discussion: There is another way to cause the bike and rider to lean. Moving the support points (?) in the opposite direction first is not the only way to cause the lean. And the last sentence (and the one before it) is wrong: a force used to move the body one way can change the CM of the bike-rider system, if done in a certain way.

Assume the initial conditions are a rider is in an upright, non-leaning, position. If the rider "shifts his weight" laterally, i.e. leans, to one side, and simultaneously exerts a downward force on the handle bar on the same side as the lean, and exerts an upward force on the handle on the opposite side (by pulling up), the bike will be used as a lever to push against the ground, via friction, and move the center of mass to the side of the lean. The force used to move the rider's body one way will not tilt (push) the bike laterally in the opposite direction.

Here's another way to think of it. Assume you don't exert any forces on the handle bars and move your body left. The bike will tilt to the right, just as the article currently indicates. Observe the angle between the plane of the bike frame and the plane through your body's CM and the bike's horizontal bar (or seat). It's acute. Now do it again the way I indicated above, pulling on the handlebars. You'll essentially be trying to prevent that angle from becoming acute. This has the approximate effect of turning the body-bike system into a rigid 90-degree lever, with you moving a mass (your body) along the horizontal member away from the vertical member. You are able to do this because the bottom of the vertical member (the bike tires) are in contact with the ground. You're pushing your body away from the point on the ground that was formally beneath you, while keeping the bike in the same upright position.

The essential element that has been forgotten is the ground (and friction with it). If the bike-body system is maintained in the correct (dynamic) configuration (as indicated above), its CM can be moved because the ground will provide the appropriate counter-force, external to the bike-body system, that is necessary.

Now, at high speed, with heavy motorcycles (or other heavy 2-wheelers), I'd believe it if you claimed a rider's weight will have difficulty exerting enough force to overcome the spinning-wheel-induced net torque that provides self-stability. But that involves different forces and would be another discussion.

Suggestions for correction:

1. Remove indicated sentence in 2nd paragraph, or rewrite.

2. Remove last 2 sentences, and "and the only way to cause that lean (of the combined center of mass of bike and rider) is to move the support points in the opposite direction first.", in subsection Need to lean to turn.

3. Make corresponding edits in the related article Bicycle and motorcycle dynamics.

Metafax1 (talk) 07:50, 2 December 2008 (UTC)

Without a credible source, this is all just unsubstantiated hypothesizing. The points you question, with templates are already footnoted. Read the conditions for disputing the accuracy of an article or section. The current article "content is from verifiable reliable sources and that it is unbiased and contains no original research."

I expect that you will not be able to find a credible source for your theory because it is flawed. The net response of a system does not depend on how individual internal forces and torques are applied, but only on their resultant. The friction between the wheels and the ground is the same in both scenarios you describe and merely prevents the wheels from moving sideways in both cases. While it may generate a small lateral acceration of the combined center of mass of the bike and rider as the torque is applied that causes the rider to pivot with respect to the bike, that is countered by equal and opposite reactions as torque is applied to slow and stop the pivoting motion at the end of its travel. -AndrewDressel (talk) 14:14, 2 December 2008 (UTC)

No answer, so I'm taking out the disputed banners. -AndrewDressel (talk) 02:49, 6 December 2008 (UTC)

Definition 2

The article currently claims that “steering momentarily in the opposite direction causes that lean. Once sufficient lean is established to sustain the desired turn, the rider, or in many cases the bike itself, then steers into the turn to cause the bike to turn in the desired direction and stop the lean from increasing.”

This is poorly written IMHO. Countersteering, except at low speeds, in not a "momentary" action nor do you ever "then steer into the turn." You countersteer throughout the turn and only change the amount of countersteering to adjust your lean and hence the amount of turn.

The way it is currently written makes it appear that you only contersteer to start the lean, but once leaning, you then steer like you would a car, i.e., steer into the turn. —Preceding unsigned comment added by Rmeigs (talk • contribs) 23:40, 19 March 2009 (UTC)

By 'countersteer', do you mean the direction of the front wheel with respect to the rear frame, or the direction of the torque applied to the handlebars?

• If you mean the direction of the front wheel with respect to the rear frame, then it is almost always in the direction of the turn. Cossalter, in his Motorcycle Dynamics, Foale, in his Motorcycle Handling and Chassis Design, and Cocco, in his Motorcycle Design and Technology, are all very clear on this point. This is described in the text you quote in your first paragraph.
• If you mean the direction of the torque applied to the handlebars, then it depends on the particular bike and the forward speed. Cossalter explains that on motorcycles it is preferably negative, opposite the direction of the turn, but usually turns positive, in the direction of the turn, at sufficient speed. This is described in the fourth paragraph of the article.
• Perhaps you are using the alternate definition of the term, as mentioned near the end of the article, describing the steer angle necessary "to maintain control in response to significant rear wheel slippage."

The current article tries to address all these cases. If you find it unclear, perhaps you can suggest an improvement. -AndrewDressel (talk) 02:10, 20 March 2009 (UTC)

steering geometry

I have looked at the three articles of the three links above. All three of them are in perfect agreement, but the third article discusses the physics in much greater depth.

To expand the wikipedia article, the dynamic behavior of the steering geometry would have to be discussed. The forefork designs of bicycles are little miracles of engineering: if the proportions are just right the steering geometry makes for a forgiving balance behavior of the bike, and it enables smooth steering. By contrast, a bicycle with a vertical steering column would be an absolute nightmare to steer.

Actually, experiment proves otherwise. See The Naïve Bike easily capable of being ridden AndrewDressel 00:01, 19 May 2006 (UTC)

To some motorcyclists it may appear as if their front wheel reads their mind, steering in the direction they want to go. Generally motorcyclists feel that they are thinking themselves through a curve.

A bike is steered by shifting its balance; the front wheel follows these shifts.

Direct experimentation by California Superbike School suggests the opposite. AndrewDressel 03:20, 19 May 2006 (UTC)

Keith Codes "no bs machine" apparently has a very small amount of trail so that particular bike can't be counter-steered indirectly via body leaning. However Keith states that it can be easily done on his dirt bikes. An off-road motorcycle will easily steer by pressing down on the inside peg - although leaning would probably work just as well, since the idea is for the rider to lean inwards causing the bike to lean outwards, which causes the front wheel to be steeered outwards due to the steering geometry (trail). Jeffareid (talk) 09:11, 1 August 2009 (UTC)

Interesting point. First, don't neglect the rest of his quotation, which includes still not what I would call good control. Second, his guess as to why this is also includes small contact patch on knobbies or dual sport tires. Third, the article already lists bike weight as an important factor in the effectiveness of hands-free steering, and even the big Honda 450cc water-cooled motocross bike weighs in at a paltry 234.8 pounds, barely more than many riders, while the small Honda 600cc sport bike weighs nearly twice as much, and easily twice as much as the average rider, at 410 pounds. Yes, the motocross bike has more trail, 4.5" vs 3.8", but only 18% more, while the sport bike weighs 75% more. I suspect that's all the back-of-the-envelope analysis we're going to be able to do. What change to the article would you suggest? -AndrewDressel (talk) 14:10, 1 August 2009 (UTC)

The balance is manipulated with well-timed, minute turns of the front wheel. --Cleon Teunissen | Talk 20:31, 10 Mar 2005 (UTC)

Contradiction

Anyone notice that paragraph two, about gyroscopic effects, appears to be contradicted by the rest of the article?

"Motorcycles turn corners using the gyroscopic roll reaction force of the spinning front wheel."

vs

"If a biker wants to turn to the right, he first throws the bike off balance by a well-timed jolt to the handlebars, momentarily pointing the front wheel slightly to the left. The center of mass of the bike plus rider will continue in a straight line, but the contact patches of the tires move to the left with respect to this straight line."

So, is it one, the other, or both? AndrewDressel 03:28, 19 May 2006 (UTC)

Not to mention that precession rate is inversely proportional to spin rate. That means that if "gyroscopic roll reaction" is really the mechanism, it happens twice as slow at 60mph as it does at 30mph. That doesn't sound desirable. Does anyone have a reference to someone who has done the math? AndrewDressel 13:10, 19 May 2006 (UTC)

I don't know about the mathematics involved, but I have experience of large capacity bikes ridden at speed, and the two gyroscopes bolted to the frame make it impossible to perform any sort of major directional changes. The bike wants to keep on going, as can bee seen in some bike races when the rider is unseated and the bike sometimes goes on its merry way without him.92.11.4.171 (talk) 16:18, 10 January 2009 (UTC)Lance Tyrell.

Since the section about the "gyroscopic roll reaction force" remains unsupported, I've taken it out. I also removed the assertion that countersteering is actually "push steering". Perhaps is it "also known as" or "might better be thought of", but it certainly isn't "actually push steering" any more than it is "actually pull steering". AndrewDressel 12:53, 23 May 2006 (UTC)

There are at least 3 different concepts involved in the actions that lead to cornering a bike at a reasonable speed. 1.) Gyroscopic forces, turn the bars to the right and gyroscopic forces pull the bike via the forks and therefore the frame,left. The steeper the steering angle the more leverage involved (GP bikes vs Cruiser bikes, which turn quicker?) 2.) The displacement of the tracking of the front wheel away from the centre of gravity of the bike. 3.) the conical shape of the motorcycle tyre. The outer section may 'bite' as it is leaned because if the shape of the surface of the tyre was to continue it would to a point and create a cone. If you push a cone on the ground what does it do? It goes around.

Also a bike can be steered at speeds of upto 30-40mph without countersteering, but it does make for very bad riding and usually relates to new riders who have yet to 'switch on' to countersteering. Countersteering can be taught to new riders or they will eventually switch on to it within a few months of riding on their own. —Preceding unsigned comment added by Bennett366 (talk • contribs) 03:38, 16 April 2008 (UTC)

I don't understand the point you are making about countersteering with the three concepts you mention above above:

1. Gyroscopic forces: I believe this only further explains the need for countersteering. The gyroscopic effect (steering torque to the right from the handlebars results in a lean torque to the left) pushes the bike in the wrong direction. Something must be done to force a lean into the turn.
2. The displacement of the tracking of the front wheel: how countersteering is described in the article.
3. The conical shape of the motorcycle tyre: doesn't indicate whether the conical shape of the tire influences the lean of the bike the into the turn or away.

As for turning at speeds up to 30-40 mph without countersteering, can you provide any reputable published (not self-published) source to refute the already provided references? Neither Cossalter and Wilson mention any speed range(s) in which countersteering is necessary or unnecessary. -AndrewDressel (talk) 13:41, 16 April 2008 (UTC)

Gyroscopic effects

Gyroscopic effects do play a role in bike steering, I think, but it is a rather technical issue, more suitable for a more technical exposition of than for the wikipedia article

In order to get to the required lean, the bike must roll. The front wheel acts like a gyroscope wheel: when there is roll, the wheel's gyroscopic response is to yaw. (For definitions, see pitch, roll, yaw.) I rather suspect that this contributes to the fact that it is possible to steer a bicycle accurately without hands on the handlebars. I also suspect that the gyroscopic effects contribute to the experience of effortlessness of well executed countersteering. --Cleonis | Talk 06:20, 25 August 2006 (UTC)

The gyroscopic effects are discussed in the Bicycle and motorcycle dynamics article. Countersteering is just about the steering input required to initiate a turn. -AndrewDressel 14:54, 25 August 2006 (UTC)

Well used countersteering has known to bend handlebars on racing motorcycles, rider input may be very forceful to get the desired steering/turn in speed. —Preceding unsigned comment added by Bennett366 (talk • contribs) 03:47, 16 April 2008 (UTC)

This, I'd love to see. -AndrewDressel (talk) 13:42, 16 April 2008 (UTC)

Yes, Virginia, racers do occasionally bend handlebars (although they normally use sufficiently high strength materials that this is not likely). To understand it, you must consider the gyroscopic effect. -—Preceding unsigned comment added by 130.20.3.179 (talk • contribs) 17:51, 21 July 2008 (UTC)

Still would love to see any documentation of this. -AndrewDressel (talk) 20:18, 21 July 2008 (UTC)

If you want to turn your bike or cycle to the left at high speeds, a quick "tug" of the handlebars to the right does not cause the wheels to go out a bit to the right as the article suggests. Rather it causes your bike wheel's angular momentum to precess such that the wheels lean to the left. The harder you try to pull it to the right, the more rapidly it will precess (i.e., the more rapidly it will lean to the left). -—Preceding unsigned comment added by 130.20.3.179 (talk • contribs) 17:51, 21 July 2008 (UTC)

Hmmm. Cossalter, in Motorcycle Dynamics, contradicts that claim. On page 304, he shows a graph of steering angle "when entering fast in a turn". For a right-hand turn, it shows nearly one full degree to the left for half a second (12 meters at 22 meters per second). That might not sound like much until you look at the rest of the graph which shows a maximum steering angle of less than two degrees to the right after reaching steady state. -AndrewDressel (talk) 20:18, 21 July 2008 (UTC)

Once torque causes you to lean to the left, the new torque created by having the center of mass to the left of the point of tire contact with the road will cause both the front and the back wheel to precess to the left (i.e., turn the corner). -—Preceding unsigned comment added by 130.20.3.179 (talk • contribs) 17:51, 21 July 2008 (UTC)

Cossalter contradicts that claim as well. He calculates the torque due to gyroscopic forces of the wheels during roll motion, and then explains that this is balanced by the lateral resistance exerted on the wheels by the ground. -AndrewDressel (talk) 20:18, 21 July 2008 (UTC)

Precession goes up linearly with the force applied and linearly with angular momentum of the wheel (which goes up linearly with ground speed). If the racing rider wants to turn quickly left, he must jerk the handlebars quickly to the right. The bike does NOT go significantly to the right at high speeds as the article would lead you to believe (although it may at low speeds where precession is a smaller effect). At high speeds the front wheel precesses, putting the bike into the lean to the left - the wheel doesn't kick out, but simply tilts over. This lean starts the turn. If you don't believe this, suspend your bike in the air - spin the front wheel rapidly - and give the handlebars a tug to the right. Or try making a top tip over by applying force outward. -—Preceding unsigned comment added by 130.20.3.179 (talk • contribs) 17:51, 21 July 2008 (UTC)

Cossalter goes on to calculate an example gyroscopic moment generated by the front wheel when the rider turns the handlebars. At 22 m/s (50 mph), a front wheel with a moment of inertia about an axis through its hub of 0.6 kgm² creates a roll moment of 3.5 Nm. He then compares this to the moment created by the lateral force on the out-tracking front wheel: 50 N on a CM 0.6m off the ground = 30 N. That's 8.5 times as much.

He goes on to explain that while the gyroscopic moment is small, it is handy because it begins instantly while the moment due to out-tracking takes a little longer to build. -AndrewDressel (talk) 20:18, 21 July 2008 (UTC)

That's why a racing rider may "bend" the handlebars (or at least apply a very serious countersteer) - to get sufficiently rapid precession at high speeds you've got to apply a large countersteering force to the handlebars - the tighter the turn and the higher the speed the greater the counterforce required to initiate the turn. -—Preceding unsigned comment added by 130.20.3.179 (talk • contribs) 17:51, 21 July 2008 (UTC)

May I submit that there might be an important qualitative difference between "bend the handlebars" and "apply a very serious countersteer". I would think that bending handlebars would be so amazing that it would be easy to find a reference. -AndrewDressel (talk) 20:18, 21 July 2008 (UTC)

The steady state precession effects are covered in the Bicycle and motorcycle dynamics article as suggested here, but there is not a discussion of countersteering developed there. -—Preceding unsigned comment added by 130.20.3.179 (talk • contribs) 17:51, 21 July 2008 (UTC)

Given that the gyroscopic effect is critical to a physicists understanding (i.e., a correct physical understanding) of what happens when you countersteer at high speeds, it is sad that the people who set Wikipedia’s standards think a Wikipedia article should be dumbed down such that anyone is capable of "understanding" it. Einstein said, "Everything should be made as simple as possible, but not simpler." -—Preceding unsigned comment added by 130.20.3.179 (talk • contribs) 17:51, 21 July 2008 (UTC)

I certainly have no idea what Wikipedia standards require a dumbing down. I do appreciate Wikipedia's policy of verifiability. -AndrewDressel (talk) 20:18, 21 July 2008 (UTC)

I think we've succeeded in making it "simpler than possible" for the sake of the "'average reader'". But then what does one expect when articles are written by experts who turn out to be unqualified people. This contributes to the lack of accuracy that has long been the strongest valid criticism of Wikipedia articles. -—Preceding unsigned comment added by 130.20.3.179 (talk • contribs) 17:51, 21 July 2008 (UTC)

Wow, Wikipedia has the same problems with fraud as does Science. Are you suggesting that we solve the problem by believing anonymous posts instead? -AndrewDressel (talk) 20:18, 21 July 2008 (UTC)

• This needs to be fixed, the gyro roll torques are about 1% of the total, not 12% as stated in the article. From the discussion page for Bicycle and motorcycle dynamics: Gyro roll torques are overstated. I make the spin velocity of the front wheel about 11 x 2 x pi radians/sec (I'm presuming a typical motorcycle radius of 0.32 m). For the inertia (0.6 kg m^2) and the turn rate of 2 degrees/second (1/30th of a radian/sec) then I'm getting about 1.4 Nm. Moreover, 1 degree of slip angle will generate substantially more than 50N of lateral force under the weight of the front end of a motorcycle. (It must be a motorcycle, no bicycle would have a CG at 0.6m and a front wheel inertia of 0.6 kg m^2.) The value would be more like 250 N, giving 150 Nm of roll moment - the gyro torques are 1% of the total, not 10%. Black bird blue (talk) 14:51, 5 December 2008 (UTC) [http://en.wikipedia.org/wiki/Talk:Bicycle_and_motorcycle_dynamics#Turning._Explanation.3F] Jeffareid (talk) 08:34, 21 April 2009 (UTC)

Yes it does. (That is, I agree with your arithmatic.) -AndrewDressel (talk) 18:13, 21 April 2009 (UTC)

OK, but I don't feel qualified to make such a change. Perhaps it should be removed until it can be properly editted. Jeffareid (talk) 05:30, 23 April 2009 (UTC)

Let's see if I can sort this out. Cossalter, on page 297 of Motorcycle Dynamics, gives an expression for the gyroscopic moment due to turning a spinning front wheel:

$M_{g}=I_{wf}\omega _{f}{\dot {\delta }}$

Then, on page 303, he begins a numerical example with $v=22{\text{ m/s}}$ and $I_{wf}=0.6{\text{ kgm}}^{2}$

He then concludes that the "gyroscopic roll moment is about 3.5 Nm."

He doesn't specify a wheel radius, but uses 0.3 m earlier in the book, as in examples 1 and 2 on page 12.

That would yield a spin rate of $\omega _{f}={\frac {v}{r}}={\frac {22{\text{ m/s}}}{0.3{\text{ m}}}}=73.33{\text{ rad/s}}$

Although he does not state it explicetly, this requires that he is using a steering rate of ${\dot {\delta }}={\frac {M_{g}}{I_{wf}\omega _{f}}}={\frac {3.5Nm}{0.6({\text{ kgm}}^{2})(73.33{\text{ rad/s}})}}=0.07955{\text{ rad/s}}=4.56{\text{ }}^{\circ }{\text{/s}}$

This number appears to come from a graph on page 304 that shows steering angle reaching -2° in about 0.5 seconds: about 4°/s. Perhaps he is using a peak value.

Finally, at the top of page 304, he simply states "The leftward lateral force reaches a maximum value of 50 N after about [0.1 seconds]. Its tilting moment with respect to the mass center (height = 0.6 m) is equal to about 30 Nm."

I'm afraid that without a different source, I'm going to have to let the current numbers stand. -AndrewDressel (talk) 18:55, 3 June 2009 (UTC)

Physical experiment

"The physical countersteering phenomenon without use of the countersteering technique is illustrated by the following simple experiment: Balance a bicycle by walking in a straight line and only holding on to its saddle, then initiate a turn by leaning the saddle in one direction. One should observe the front wheel momentarily flopping in the opposite direction of the turn before turning in the direction of the turn." - Ilanpi (13:57, 7 January 2007)

- I do not recall seeing this in print before. Is there a source we can cite? -AndrewDressel 16:57, 8 January 2007 (UTC)

- This effect is counter to that created by gyroscopic forces of the spinning front wheel, and I suspect this must depend on the geometry and mass distribution of the front end and the rate of the induced lean. Do any details exist of what conditions must exist for this to work? -AndrewDressel 16:57, 8 January 2007 (UTC)

- Nice clarification of the two possible interpretations of the term, by the way. -AndrewDressel 17:02, 8 January 2007 (UTC)

The sequence described by Ilanpi is different from what I would expect. There is also the following awkwardness: in walking beside a bicycle, and tipping it over, the leverage for tipping it over came from the feet resting on the pavement. So this example raises a question as much as it attempts to answer one: where does the leverage for tipping the motorcycle come from? In the case of a motorcycle driven at speed, gyroscopic effects become significant. Because of the bike's tendency to remain upright (gyroscopic effect) it is hard to tip it sideways, but at the same time it gives the rider the leverage to really shift his weight, say to the right, and subsequently tip the bike to the right with his sheer weight. However, a bicyle weighs much less than its rider so the leverage due to gyroscopic effects is insignificant. If, when riding a bicycle, I tip my upper body to the right, the bicycle tips to the left as there is no leverage to shift the common center of mass; the common center of mass keeps going in a straight line. As described in the article, when the technique of countersteering is used to prepare for cornering, the center of mass keeps going in a straight line, and the contact patches of the tyres are moved away from the straight line. --Cleonis | Talk 13:07, 9 January 2007 (UTC)

Even though the center of mass of the entire system does not lean, when torque is applied between bike and rider, the bike does lean, at least in the case of light and/or slow bikes, and so the front end does react. The question, for me, is whether the front end reacts as Ilanpi describes. I can see it happening of the center of mass of the front end is sufficiently forward of the steering axis and the lean is induced rapidly enough. Then the front end will lag behind the lean, due to its inertia, and effectively steer opposite the lean momentarily until other factors cause it to steer towards the lean. However, all this guessing doesn't really matter if we can't find a citable source, right? In fact, the existing physical experiment I already cite, the "No B.S. Machine", claims the opposite: rider lean by itself cannot steer a motorcycle. -AndrewDressel 17:48, 9 January 2007 (UTC)

I agree that it doesn't matter if no citable source is available.

I just read the "No B.S. Machine" webpage. That looks very convincing to me. The modified motorcycle's front wheel is freed to follow the lean of the bike. I think that modified bike is very effective in demonstrating to people they have made the wrong attribution: all the time they have actually been employing countersteering. ::::That said, on a smooth surface, a bicycle can be steered hands-free very accurately. The principle is the same: first the bicycle is thrown off balance, then the front wheel follows.

By the way, I also own a uni-cycle. I never became any good at riding it, but I learned enough to experience that the only way a uni-cycle can be steered is through camber steering. In the case of a motorcycle, if the tires are quite fat and round, camber steering will make a significant contribution. --Cleonis | Talk 18:58, 9 January 2007 (UTC)

Andrew notes that No-B.S. reveals, "rider lean by itself cannot steer a motorcycle." That is exactly true. As I added in my edit at the top of this article, countersteering "is the only way a rider can cause a single-track vehicle at speed to turn." When novice riders take an MSF Basic RiderCourse from me, every one of them understands this concept before the course is over. "Press right to go right, press left to go left." I do not understand why it can be so difficult for experienced riders to understand this. When riding a motorcycle, all one needs to do is try it in order to believe it. Once one understands this, one has in hand a powerful technique in the operation of a motorcycle. Jeff dean 00:05, 10 January 2007 (UTC)

As the feedback slows to a trickle, I've tried to clean things up a bit. I'll leave in most of the addition, but remove the, as yet, unsourced experiment. I'd love to find more details about that. -AndrewDressel 19:18, 11 January 2007 (UTC)

Although the "no bs-machine" doesn't steer well with rider leaning, Keith Code readily admits it works well on his dirt bikes. My guess is that the "no bs-machine" has a small amount of trail, with little lean to steer coupling, unlike a dirt bike (large amount of trail, higher rider to bike mass ratio), so indirect counter-steering by leaning doesn't work on the "no bs-machine". I assume there's no steering damper on the "no bs-machine", as that would be "cheating". Since lean to steer coupling diminishes to virtualy zero at racing speeds on any bike, and since it is a racing school, it's important to teach proper countersteering. Jeffareid (talk) 17:33, 21 April 2009 (UTC)

The article currently states "on a sufficiently light bike (especially a bicycle), the rider can initiate a lean and turn by shifting body weight." -AndrewDressel (talk) 18:13, 21 April 2009 (UTC)

Sorry if I've been imprecise. I made up this experiment and performed it under non-scientific conditions (and by my students at Stanford under similar conditions) so it doesn't have the validity required for this article. However, I believe it reflects the truth and I leave it here as a "thought experiment." I completely disagree that a motorcycle cannot be steered by body weight alone. The reason is that a bicycle can easily be steered no hands and there is no qualitative difference between a bicycle and a motorcycle as regards balance, apart from relative weight of rider and machine(if someone disagrees, I would appreciate an explanation). In particular, there are thousands of expert motorcycle riders in the world who can ride a motorcycle no hands perfectly well, at least in a straight line. For example, it is traditional for GP motorcycle racers to ride no handes on their victory laps, and even to stand on the pegs. I have seen such riders initiate a turn while standing on the pegs, though they grab on to the bars shortly thereafter. However, it must be noted that riding no hands in a straight line already requires the ability to turn no hands, since keeping a straight line requires constant adjustment of trajectory. This proves that the statement that a motorcycle cannot be turned by rider lean alone is false. ilan 16:01, 12 January 2007 (UTC)

No sweat. It is an interesting thought experiment, and I don't doubt that it happens. I just wish we had a source, and I would like to know what conditions are necessary. As for motorcycles, I tried to express in the article that it is a matter of degree that varies with relative weight (quantitative, not qualitative). Hence the terms "heavy bikes (many motorcycles)" and "ineffective at initiating turns." I imagine that 500cc GP bikes are quite light. -AndrewDressel 15:35, 12 January 2007 (UTC)

Thanks. I've changed my comment above to be slightly more precise. I've looked at your website and see that you are teaching Mechanics. You could try to study my experiment, assuming you have nothing better to do :) Otherwise, it is true that 500cc GP bikes are (were?) light, however, there are still no hands victory laps with the heavier Moto GP 4-strokes, whose weight (up to 350lbs) approaches those of standard street bikes, and keeping in mind that GP riders typically weigh less than the average motorcycle rider (they all had to move up from the 125cc class), the conclusion is that rider/vehicle weight ratio for GP racers is probably not very different from average rider and motorcycle. ilan 16:23, 12 January 2007 (UTC)

Perhaps, in addition to defining heavy and light motorcycles, we need to define turning. I don't know what the course looks like, but the issue may be that negotiating a victory lap no-hands is very different from turning onto a side street, avoiding a pothole, etc. -AndrewDressel 18:02, 12 January 2007 (UTC)

By the way, here are some more things to consider, which, at least to me, show that a precise understanding of the physical phenomenon is quite difficult: A. There is no mathematical theory of the bicycle because it is a non-holonomic system. As far as I know, there has been no conceptual advance since the publication of the book "Theorie der Kreisels" by Klein and Sommerfeld about 100 years ago. Ten years ago, I went to a talk by Jerrold Marsden of Caltech, where he modeled simpler objects (I think it was a snake-board) but he said that his methods could not deal with the bicycle at all. ilan 16:23, 12 January 2007 (UTC)

I believe you are mistaken to say that "there is no mathematical theory of the bicycle". Even though the non-holonomic constraint makes it complicated, there have recently been some excellent advances. For a comprehensive state of the field, read "Linearized dynamics equations for the balance and steer of a bicycle: a benchmark and review" By Meijaard, Papadopoulos, Ruina, and Schwab. (Online at http://ruina.tam.cornell.edu/research/topics/bicycle_mechanics/papers/BicyclePaper1Andyv38.pdf) Also check out JBike6, a software implementation of the benchmarked linearized equations of motion. (Online at http://www.tam.cornell.edu/~ad29/JBike6/index.htm). The benchmarking was performed with several fully-nonlinear models implemented in various mathematical packages, such as MATLAB, SPACAR, and AutoSim. The motorcycle industry has made similar gains. Check out FastBike at www.dinamoto.it -AndrewDressel 18:02, 12 January 2007 (UTC)

Thanks for this reference, I hadn't realised that some theoretical progress had been made. However, I should read the article carefully to make sure. I have some more comments about countersteering which actually could go into the main article (though they are based on personal experience). As I noted before, even riding in a straight line requires steering input. In particular, this explains what I consider to be a main difficulty in learning how to ride a bicycle, which is that the pedaling motion causes the bike to lean in the direction of the downwards pedal stroke and this has to be counteracted by turning the handlebars in the direction of that pedal stroke. I frankly have never heard anyone make this remark when teaching cycling (and I suspect that most persons instructing a child would say the reverse), I figured it out when I taught myself to ride backwards, that is, sitting on the handlebars and had to learn to turn the bars in the reverse direction from usual (with respect to my body) at each pedal stroke. One can observe this handlebar motion in any bicycle that is being pedaled, e.g., in television coverage of the Tour de France. Similarly, a motorcycle moving in a straight line will also require constant trajectory adjustment which is reflected in handlebar motion. Observation of handlebar movement can be used to determine whether actors in a movie or television series are actually driving their bicycle or motorcycle, or simply being towed on with the vehicle resting on a trailer (as is often done to appease insurance companies). In particular, I doubt Erik Estrada ever actually rode a motorcycle on the TV series C.H.I.P.S. and you can determine exactly which scenes in the movie Breaking Away were actually shot on a moving bicycle. ilan 19:10, 12 January 2007 (UTC)

B. It is perfectly possible to ride a motorcycle which suffers from a speed wobble, that is, whose front wheel is constantly oscillating, including riding such a bike no hands in a straight line. ilan 16:23, 12 January 2007 (UTC)

Continuing on the theme that things are hard to understand, I just remembered a case where a motorcycle is able to go in a straight line with no steering input and independently of rider body position. It concerns the person who makes his living by taking a large motorcycle, driving it at high speed, then getting off the bike and dragging himself by holding on to the back -- I think he has special metal-soled boots. I don't even know where to find a reference for this! ilan 16:34, 12 January 2007 (UTC)

These two examples, if anything, suggest a motorcycles' tendency to remain moving in a straight line despite outside, non-steering, input. -AndrewDressel 18:02, 12 January 2007 (UTC)

Sorry, but you've got me started on one of my rants, that is, everything I write in this paragraph is based on personal anectodal experience, though the opinions will be stated in extreme terms, as if I had the weight of actual scientific evidence to back it up (actually this applies to most of what I write). Anyway, my personal experience with motorcycles was limited to small (<= 400cc) bikes and to a medium (700cc) bike with 16 inch wheels, and my steering of these vehicles was done by the countersteering technique alone, that is, I used the handlebars exactly like a car steering wheel (with the initial countersteer) with no body weight input. Then one day I drove a friends 1000cc BMW with 18 inch wheels and very short stubby bars. I tried my usual countersteering method and nothing happened, no matter how hard I applied pressure to the bars. Since a turn was rapidly approaching, I had to do something, and finally managed to get it turned by leaning my body. I noted that I hardly used any pressure on the bars. This experience convinced me that countersteering alone is not always sufficient to turn a motorcycle (exactly the opposite remarks of what was written by another user above). Just to get a little more objective, I read in Keith Code's motorcycle book that the force necessary to countersteer a GP bike is quite high, so an estimate of this force, if it is greater than the possible force applied by the rider (as measured using weight machines), would corroborate my assertion. ilan 16:58, 12 January 2007 (UTC)

I know what you mean about the frustration of using personal experience in Wikipedia. I've learned to use mine as a guide for finding citable references. For example, I know from personal experience that a long steering boom, such as the one on my Burley Canto recumbent, will overwhelm other self-stabilizing effects, but I cannot find a source, and so I've had to remove it from the Bicycle and motorcycle dynamics article. -AndrewDressel 18:02, 12 January 2007 (UTC)

Comments about once lean is achieved

"This is incorrect. If you try to steer into a turn after setting up a lean and starting it, the countersteering effect will straighten you up again." -116.93.137.34 (Talk) 19:58, 15 March 2008

Perhaps a little further clarification is in order. As described and referenced in Bicycle and motorcycle dynamics, a bike's tendency to deepen or lessen the lean angle in a turn depends on its geometry, mass distribution, and current forward speed. If the speed is below the inversion speed, the self-stability of the bike will cause it to tend to steer into the turn, thus righting itself and exiting the turn, unless a torque is applied opposite the direction of the turn. At speeds above the inversion speed, (the case currently described in this article) the capsize instability will cause it to tend to steer out of the turn, thus increasing the lean, unless a torque is applied in the direction of the turn. At the capsize speed no input steering torque is necessary to maintain the steady-state turn. -AndrewDressel (talk)

Again again, there is utter confusion between position-based control and force-based control. Black bird blue (talk) 13:21, 5 December 2008 (UTC)

The article states that at high speeds, an inwards torque needs to be applied to the handlebars. Jeffareid (talk) 09:07, 21 April 2009 (UTC)

The complete quotation is "The actual torque the rider must apply to the handlebars in order to maintain a steady-state turn is a complex function of bike geometry, mass distribution, rider position, turn radius, and forward speed. At low speeds, the steering torque necessary from the rider is usually negative, that is opposite the direction of the turn, even when the steering angle is in the direction of the turn. At higher speeds, the direction of the necessary input torque inverts to become positive, that is in the same direction as the turn." This is accompanied by a reference from Cossalter. -AndrewDressel (talk) 18:13, 21 April 2009 (UTC)

I believe that at high speed, virtually no input is required to maintain a lean angle. This is based on my own experience, a conversation with a Bonneville streamliner bike rider named Sam Wheeler [http://www.streamliner.com], and articles regarding motorcycle racing. I only had one experience with turning at 100+ mph on a track, and while in a turn, the motocycle simply held it's lean angle and greatly resisted any effort to change that lean angle. It took virtually the same effort to lean inwards as it did to lean outwards back to vertical. Zero steering input resulted in zero perceptible lean angle change at high speed. Jeffareid (talk) 09:07, 21 April 2009 (UTC)

This sounds like anecdotal evidence based on two particular bikes. -AndrewDressel (talk) 18:13, 21 April 2009 (UTC)

Also all those racing bikes referred to in those magazine articles I read. I corresponded with Keith Code a while ago, and he mentioned that most racer replica and true racing motorcycles are neutral, without any tendency to lean inwards or outwards at any reasonable (well above walking) speed. I'll ask for further clarification on this. In addition this falling inwards at high speed is part of capsize mode, and the actual treadmill results conflicted with the theoretial results as shown in the graphs for stable speed range in the Delft University article below. Jeffareid (talk) 05:35, 23 April 2009 (UTC)

Regarding capsize mode, note that a graph in an article from Delft University (link below) shows a capsize mode asymptotically approaching a value just barely above zero as speed increases. The article shows a stable speed range for a particular bicycle that stops below 8 m/s, but then a video from Delft University of that very same bike on a treadmill at 8.33m/s (30 kph) describes it as "very stable".

Link to article: Koo06.pdf

Link to web page with videos: treadmill measurements Jeffareid (talk) 09:07, 21 April 2009 (UTC)