oldfrt

Actually, 90 degrees is not possible because the g force would go to infinity. It's just a theoretical way to view the mechanics and geometry of turning.

I'm thinking of "lean" relative to a horizontal plane instead of the road surface. All the tilt of the road surface does is to move the contact patch. Here's another way to see it. Travelling in a circular path, the lean of the bike would generate a cone. For a given circle, as the lean increases the apex of the cone flattens until if the lean went all the way to 90 degrees the cone would flatten and become a disc. At that point the steering head is not turning. That's also why you can negotiate slow speed turns by letting the bike lean into the turn that you can't accomplish by just pushing the bike through upright.

I think you're right that the wheel would or could be pointed slightly into the turn in some or maybe most turns, but here's what I'm thinking. If the bike were going around a circular track that was banked such that the lean was perpindicular to the track then there would be no turn in the bike geometry. Taking that concept to the extreme, think about a bike in a spherical cage. It can actually do vertical loops. Certainly it's not turning at that point. Then again, back to the banked circular track. Take away the banking and the track is flat. The bike is still leaned but now the contact patch is on the side of the wheel instead of centered. As far as the bike is concerned it might as well just be riding on a banked straight road maintaining a contact patch off-center of the tires. The difference is just more g's in the turn. I believe the amount of turn in the bike geometry is more due to the lean than to the turn radius in the road or track. On the other hand, if you stand holding the bike and keeping it vertical push it around in a circle with your body as the center it's obvious that the wheel has to be turned to the locks to go throught the turn. Leaning the bike to the inside will allow it to turn tighter. If the bike could be leaned all the way as if you were standing in a spherical cage, then it could do the turn with no turn in the bike geometry. I just talked myself into agreement with you. The bike is always turned slightly in the turn direction but the bike geometry turn decreases as the lean increases and would go to zero if the bike were leaned 90 degrees. This is just something I have been thinking about for some time and have wanted to understand a little better. Hope the subject is not boring or annoying to others. Or even useless.

Are you sure?

Definition of going in a straight line: The front wheel is in a plane with the rest of the bike, the steering head is pointing straight ahead, and the back wheel is exactly tracking the front wheel. Isn't this exactly what is happening when you're leaned over in a constant radius turn and maintaining a constant speed?

What's the answer? I could guess but I'd probably be wrong. OK here goes anyway. Let off the brake, roll on some throttle (not a lot) and do a quick-turn as soon as you clear the wet spot. Right? Wrong?

I'm back. I rode my bike around at walking speed to experiment with countersteering at slow speed. I found that whenever I applied force to turn the handlebars right, the bike steered to the right. That's the opposite of countersteering, which would have caused the bike to steer left. Obviously, at slow speed, you have to maintain the balance of the bike with body weight shift. If you turn hard to the right the bike will fall to the left, but if you turn slowly to the right and maintain balance, only force to turn the handlebars to the right is required. I can't agree with the definition that steering the bike toward the c.g. to maintain balance is countersteering, when in fact you are actually applying force to turn the wheel in the direction you want the wheel to turn. So I now bid a fond adieu to this discussion. I feel like the one juror who hung the jury and have become a pariah in the motorcycling community, maybe a veritable outcast and and a heretic. O well..... Regards to all and ride safe..

Turning the handlebar to the right moves the contact patch left. This moves the cg of the bike to the right of the line between the two contact patches, causing the bike to lean right. If this is done slowly, the bike should (I'm not too sure now?) keep turning right. If done quickly the right turn will definately cause the bike to lean left and that will have to be corrected and a compensating turn to the left will be required. My point is that at slow speed, inputting a right turn to the handlebar makes the bike turn right and that at high speed inputting a right turn to the handlebar makes the bike turn left. Restating, at slow speed the bike responds directly and immediately to your input and at high speed the bike responds exactly oppositely and immediately to your input. I agree that slow speed maneuvering is a balancing act and you have to induce the bike to lean in the direction of the desired turn. Your points are all well taken and I dont have time or daylight to experiment now, but in a few days I'm going to go out and apply what I stated above. We may be close to agreeing on everything except the definition of countersteering. I may be wrong about the slow speed slowly induced turn and will be happy to admit that after I get a chance to try it again. In the words of 'whats his name' , "I'll be back".

I'm going through a step by step turn at low speed to illustrate and maybe prove that you don't countersteer at slow speeds. You can obfuscate the issue all sorts of ways by claiming the need to steer opposite the desired turn to induce the required lean and call that countersteering, but please go through these points and tell me where I'm wrong. 1. The bike is balanced and going straight ahead at slow speed. I want to turn right. 2. I pull on the right handlebar to steer right. 3. The wheel turns right thus allowing the rake/trail to move the contact patch to the left. This induces a force at the contact patch to the left and the push to the left causes the front wheel to go right. Similar to an ice skater pushing off to the left to make a right turn. 4. The wheel steering turn also causes a slight lean to the right in the front wheel due to the rake of the front forks. Conclusion: The steering input caused the front wheel to turn right, displaced the front wheel to the right by moving the contact patch left, and leaned the front wheel to the right and is now steering to the right. I think this completes the turn initiation. A bike with no rake or trail will not handle this way and would have to be balanced and turned by just moving the cg around. Refute these points for a bike with rake and trail (with the rear wheel fixed in a vertical plane for reference) a. A right turn moves the contact patch to the left b. A right turn leans the front wheel to the right

When I start googling the subject of countersteering I find that Wikepedia seems to agree with you, while some other sites agree with me. I for now remain loyal to myself. We can't even agree on the definition. Doesn't seem to be much point in debating further? One more comment on slow speed turning, however. The following comment addresses how turning the wheel to the right will cause the bike to lean to the right, because the front contact patch will have moved to the left. Also, if you haven't already noticed, the rake of the front wheel actually leans the front wheel in the direction of turn relative to the plane of the rear wheel and the rest of the bike. Why am I the only one arguing that precession is the driving force? Could I be wrong? NAH!!!!!

If we define countersteering as applying a turning force opposite the direction we want the bike to tuirn, then applying a turning force to the right to make the bike go further to the right is not countersteering. The fact that you wanted the bike to turn harder to the right to cause a lean to the left is irrelelevent to the discussion. In your case you applied turning force in the same direction you wanted the bike to turn. I don't see what difference it makes why you wanted it to turn. I watched the video several times and was not convinced either way. Can one of those things be ridden by countersteering? In other words can steering at speed be accomplished solely by pushing on the handlbar in the direction you want the thing to steer. I will be surprised if the answer is yes, and will re-consider my countersteering opinion. Once we get this settled, I guess we can start on global warming and evolution.

tz, Good point about your video. In that case the steering force was hard enough to steer the wheel out from under the bike. So now explain how progressively harder steering force produces progressively greater countersteering turning even after the turn is initiated. I completely understand the first sentence. I totally disagree with the second sentence. In this case you wanted to steer to the right so you turned the wheel to the right. If countersteering you would have applied force to turn the wheel to the left. You're trying to make the point that you countersteer at all speeds. I'm arguing that you don't countersteer at slow speeds, but that when the speeds increase then gyroscopic precession comes into play and countersteering rules. There's a transition zone also, such as parking lot speeds. I'll be convinced that you're right and I'm wrong when I see if a bike countersteers at speed with no precession, such as with the counter-rotating rotors. The rotors would have to have the same angular momentum as the wheel to eliminate precession, as well as being in the same plane and on the same axis.

I totally disagree with that statement. When countersteering, the tire is not steered out from under the bike. Demonstrate for yourself. Going straight ahead at a moderate speed apply a slight countersteering force and observe the bike turning. Apply the force progressively harder and the bike will turn progressively quicker. You will not observe any "steering out from under" of the front wheel. So, who are you going to trust? Me, or your own eyes?

I think you need to think about that one again. Fall to the right and steer to the right by pushing on the left bar. Thats the opposite of countersteering. You were falling to the right so you steered farther into the right to correct, allbeit to make the bike fall back to the left. You're steering in the direction you want the bike to go. Countersteering is steering force applied in the opposite direction.

Tim, do you believe that during an entire right hand turn your front wheel remains pointed to the left? No, absolutely not. I have observed the wheel pointing in the direction of turn when countersteering was initiated. I never said that the wheel would be pointed to the left? Do you not believe that applying a force to turn the front wheel to the left actually causes the bike to turn to the right? An interesting phenomona is if you imagine a motorcycle in a stable turn on a curve thats banked at the opposite of the angle of lean so that the bike is perpindicular to the road surface. In this case the bike is turning following the curve, but at the same time it's not turning. The front wheel is in the same plane with the rest of the plane of the bike and the handlebars are not turned at all. The bike is actually tracking inside of an imaginary cone (or it could be a sphere) if the bank could be extended downward to a point of intersection. Anytime the back wheel is exactly following the track of the front wheel, there is no need for the handlebars to be turned at all. In fact, if the handlebars are turned the back wheel track does not follow the front, but follows a path to the inside (unless you're flat-tracking). I'm pretty sure I can prove this geometrically if challenged. Maybe this is a little off point, but it's part of the turning phenomina.

The above is a key point. If precession drove lean angle changes, then not only would the bike lean over when you countersteer, but when you stopped countersteering the bike would stand right back up when trail repositioned the wheel on the path of travel. That doesn't occur. Not true. When you stop applying a force the bike or wheel will tend to stabilize in the position it is in when the force is released. Otherwise you could say that if you countersteered through a 90 degree turn, when you quit countersteering the bike will un-countersteer back through the 90 degree turn. When I countersteer into a turn, I can coast through with hands off if I want. Turning the bars right moves the contact patch left causing a lean to the right while at the same time the right hand turn leans the bike to the left via centrifugal force. Thus you have stability.

You guys are correct about precession not being the dominant force if the facts you posted above are true, i.e. 1. Bikes countersteer quicker/better with lighter wheels 2. Turning the front wheel hard over when it's in the air has little or no effect on lean. 3. Single track (wheeless) vehicles countersteer.l I may have to abandon my precession argument and admit I was wrong. Won't be the first time. However, the "facts" cited above could be somewhat subjective so I'm not entirely giving up. I'd like to hear the official "guru" opinion. As far as slow speed turning, it seems simple geometry. If you sight along the rake of the front wheel it intersects the ground at an point somewhere in front of the contact patch and remains in a plane with the rear wheel no matter which way or how much the front is turned. It's the contact patch that moves. When the bike is going straight ahead with no lean and the handlebars are turned to the right, that moves the contact patch to the left and the bike is now tending to fall to the right, the wheel is already turned to the right to allow centrifugal force to compensate and everything is happy. That's not countersteering. I went wobbling out of my driveway the other day demonstrating this to myself. When I'm going slow I steer by turning into the turns, the opposite of countersteering. Unless I'm just fooling myself.

The front wheel initiates the turn, the rear follows. Notice also that in the video that if a leaning force is applied (in this case the string is applying the leaning force) that the wheel then turns IN THE DIRECTION OF THE LEANING FORCE. I agree the back wheel resists turning and leaning, but it is overcome otherwise the bike could not turn at all. Well, it would be very difficult. What if a bike could be built with wheels that had no mass at all? No precession would be present. I believe the bike could be steered much as it is steered when just rolling along at a slow walking speed (no countersteering). This thread is about countersteering and I believe that gyroscopic precession is the driving principal of countersteering. Most people believe that at speed, countersteering force turns the bike and progressively greater countersteering force turns the bike harder. I can prove this to my satisfaction every time I ride. Hope you had a happy new year and Merry Christmas.

Here's a 30 second video illustrating gyroscopic precession. It shows the bicycle wheel hanging from a string attached to one side of the axle and the wheel rotating around the string while spinning on the axle. The force on the string (weight of the wheel) represents the countersteering force on the handlebar. Rotating around the string represents leaning caused by precession. It looks contradictory because the wheel is remaining vertical (although spinning and rotating), however if you view it from the right side (relative to the man in the video) at the beginning of the clip you will be in the same relative position of a rider pushing on the right handlebar and the wheel rotating around the string to the right represents the leaning to the right of the wheel. At the end of the clip you are viewing the wheel in the relative position of a rider and it's obviously leaning right with a right hand push. You can stop the video and play it frame by frame. You may have to play it over several times to see what I'm talking about. http://static.howstuffworks.com/mpeg/gyro.mpg Above is the video http://science.howstuffworks.com/gyroscope1.htm Above is the link "how stuff works" I believe it explains in some detail the theory of countersteering.

It would be interesting to carry the counter rotating brake rotor to a sufficient extreme and reverse the gyroscopic precession effect. Could be done by increasing rotor speed or rotor weight.

Thanks. I finally did read the article. I didn't see anywhere that it discussed countersteering, but only proved that precession is not necessary, although is helpful, for stability. Actually it said that precession is necessary for stability of the naive bike if ridden hands off. I looked but did not find that it mentioned what force applied to the handlebars is used to initiate a turn, i.e. left or right torque to turn the bike left or right. Do you still countersteer? Also I'm not sure that all the gyroscopic forces are cancelled in the models because the counter-rotating mass while in the same plane is much further away from the rotation of the yoke.

You're saying that to turn left, you first apply handlebar torsion to the right to destabilize the bike so that it leans left, then you apply handlebar torsion to the left to steer into the left turn? I believe that to be totally wrong. The entire action is right hand torsion by pushing on the left handlebar and the turn is achieved almost entirely by gyroscopic precession. The more you push on the left hand grip the more you turn. I think the posts on the thread "quick turn clarification" support this. You can prove this for yourself by coasting into a turn with "hands off" and only applying countersteering pressure in the direction of the turn by pushing with the heel of the hand in the turn direction with no pressure from the opposite hand. No opposite countersteering will be needed. I say coasting, because if applying power your throttle grip could be interfering with the experiment. I doubt if you will accept my argument, and hope someone with more credentials will jump in and "set us straight".

I understand that... I wasnt questioning you I was questioning Woody.... Se the quote above my post, that is what I was questioning. I was'nt directing my comment at you, but Woody. The school teaches that countersteering is what initiates the turn and that body steering is not an effective way to steer a motorcycle.

To understand precession you can get a bicycle wheel and an axle. Hold the axle horizontal while the wheel is spinning in a forward direction. Try to rotate the wheel to the right holding the axle horizontal. The wheel will LEAN to the left same as if you were pushing on the left handlebar. This is not just a theory, but a law of physics.

Good article. Couple of observations. Precession is the term (spelling). Also brake, not brake. The important thing about countersteering is that when you push with your right hand gyroscopic precession causes the wheel to LEAN to the right. If the wheel had no spin the lean would not happen and the wheel would turn to the left. It's the LEAN that is causing the turn as well as that gyroscopic precession is actually resisting a turn to the left. It's almost as if you were riding straight ahead and someone had a rope tied to the top of your front fender and pulled from the right. That would obviously cause a right turn. Precession does almost the same thing. Your cup analogy was very good and correct, I believe.