| Author | Message | ||
     S320002 |
Blake, "If you are correct then steering effort and getting a bike to lean at high speeds would be much easier than at moderate speeds." How do you figure that? A gyroscope is always more stable as its speed increases. "If you are correct, then please explain to me why it is sooo difficult to get a bike to lean at high speeds." (I'll leave out the sarcastic part.) Actually I've never found it sooo difficult to get a bike to lean at high speed. Unless of course I try do it without counter steering. "Turning the wheel to the left causes the rear wheel to precess into a hard (hard is your word not mine) lean to the right? I see your point. But it is a negligible 2nd order effect and your theory is way off base." A 2nd oder effect but an important one. Firmly on base. "According to your theory, once tracking steadily through a curve, the action of the turning motorcycle would cause the bike to right itself through the precession of the wheels." (Agian the sarcasm has been deleted) Quite true if by turning you mean counter steering into the direction of the turn. Refer back to my example of steering through a high speed chicane. "I should note, in anticipation that you will bring it up in support of your theory, that some motorcycles' tendencies to want to self right in a turn are due to the effects of their steering geometry, not gyroscopic precession. The fact that many motorcycles do not exhibit this tendency, my M2 included, refutes your theory conclusively." Actually the self righting tendency is due to both. Try this with your M2; While riding at 50 mph or so on a straight smooth road remove your hands from the bars, with the bike tracking in a straight line, keep your body still, GENTLY bump one of the bars. The bike should oscillate a couple of times then return to a straight line. If it does not you have a problem with either wheel alignment, steering head bearings or geometry. "Mount counter-rotating gyros on the front and rear axles of a motorcycle to exactly offset the gyroscopic effect of the wheels. The bike will steer as quickly, actually more so, at high speeds as it does at low/moderate speeds. If you are correct then steering effort and getting a bike to lean at high speeds would be much easier than at moderate speeds.How can that be if, as you contend, the gyroscopic precession of the wheels is what steers a bike at high speeds? Can you please explain that?" Have you performed this experiment? Actually it seems to me that the system would be highly unstable. "Also, some GP bikes utilize a counter-rotating crankshaft, the engine spins opposite in direction to the wheels. Why? To help reduce the total gyroscopic effect carried by the bike at high (engine) speeds. Why? To enable quicker/easier steering." Actually I stated that on this board nearly a year ago, you forgot the engine part. Whats your point? "I'm sorry you are as stubborn as I am." Stubborn, determined, persistent, resolute. Nothing wrong with that. Where would we be if Erik didn't have a good dose of the same? I enjoy the challenge. Greg;-) | ||
| Rick_A |
Right. If you counter steer any bike will turn relatively easily at high speed. ...and about a bike wanting to self right in a turn...IMO steering geometry has a little to do with it...but mostly gyroscopic forces and gravity. At a certain point those forces more or less find a neutral position. Compare how the fuel frames and tubers feel in turns. The tubers, being fairly top heavy tend to "fall" into turns while an XB tends to require a more deliberate input due to its lower CG...and IMO to a lesser degree its steering geometry. Let go of your bike at speed while leaned...given you don't give it any unwanted input while you eject it will track straight. That same force WILL have that same tendency in a turn, will it not? In regards to the comment about motorcycle tests...my point was that most are based on what are essentially parking lot maneuvers that I feel aren't really critical in daily riding. Wow, you can do a tight U-turn...congrats...go attack the canyons, traverse through heavy city traffic, hit the busy interstate, ride in foul weather, attack gravel roads, take immediate action to avoid the errant driver, avoid that tremendous tire carcass in your lane, stop before you hit that truck that just blocked your path...bla, bla, bla | ||
| M2me |
Blake, The reason I consider "hanging off" and "not leaning with the motorcycle" to be the same is if you do not lean with the motorcycle at some point you are going to have to slide your butt to the outside edge of the seat. The only way to avoid it is if you are a contortionist. If you look at someone from directly behind doing this you will see that one side of their butt is hanging off the motorcycle. The MSF doesn't call it "hanging off" they call it "leaning out" or "counterbalancing". But in my mind they are the same thing because, again, unless you are a contortionist, at some point part of your butt will end up hanging off the motorcycle. With practice it is a very safe, and at times, valuable skill to have. Rick_A, The states are testing whether you can control the bike. If you can successfully complete the test it means that you have at least a decent knowledge of throttle control, clutch control, brake control and yes, weight distribution on the bike. This knowledge hopefully means that the newly licensed rider will have at least a pretty good chance against real world riding situations. | ||
| Blake |
"If you are correct then steering effort and getting a bike to lean at high speeds would be much easier than at moderate speeds." "How do you figure that? A gyroscope is always more stable as its speed increases." Exactly! More stable - meaning more difficult to rotate out of plane... more difficult to rotate out of plane - meaning more difficult to lean/steer. "Actually I've never found it sooo difficult to get a bike to lean at high speed. Unless of course I try do it without counter steering." You have GOT to be kidding me. Apparently you have never ridden aggressively around a twisty roadrace track or attacked a set of high speed S-turns with vigor or even simply attempted a quick obstacle avoidance maneuver at high speed. Roadracers in top condition sometimes become fatigued, due to the extreme exertion they put forth in getting their lightweight race bikes to turn repetitively as they lap the track at race pace; they call it arm pump. "A 2nd order effect but an important one. Firmly on base." Actually it is probably closer to a third order effect. Second order meaning 1/10th, 3rd order meaning 1/100th. "According to your theory, once tracking steadily through a curve, the action of the turning motorcycle would cause the bike to right itself through the precession of the wheels." "Quite true if by turning you mean counter steering into the direction of the turn."  No, that is not what I meant at all. Once leaned over into the turn (the only purpose of countersteering) the front wheel must then turn into the curve. Don't tell me that you think the front wheel stays turned in the opposite sense all the way through the turn. When I say that the steering becomes difficult at high speeds, I mean that countersteering becomes increasingly difficult at high speeds. It's simple logic. It is simple physics, gyroscopes stabilize. Don't be afraid to lose the myth. That's all it is, a myth with some half-truths and science mixed in as with all good cons. Ever ride a scooter? They have tiny wheels with negligible gyroscopic effect. They countersteer extremely well. I don't get it. At low and moderate speeds, countersteering works extremely well. There is negligible gyroscopic effect. At high speeds where the gyroscopic effect of the wheels is more significant, countersteering becomes difficult. Yet you believe that the gyroscopic effect facilitates steering. Concerning counter-rotating gyros on front and rear axles: "Have you performed this experiment? Actually it seems to me that the system would be highly unstable. Others have. I think Kevin Cameron may have referenced the study in his book. Nope, not unstable. Not as stable, but not anywhere near unstable. "Actually I stated that on this board nearly a year ago, you forgot the engine part. Whats your point?" My point is that if gyroscopic precession were advantageous to the handling of a motorcycle, they certainly would not want a counter-rotating crankshaft/flywheel as it would tend to cancel any beneficial effects. My point is that the opposite is true. | ||
| Blake |
Rick, "Right. If you counter steer any bike will turn relatively easily at high speed." Be sure to inform all the engineers in Superbike and Moto GP of that so they can stop wasting their time trying to design bikes that will steer more easily. "...and about a bike wanting to self right in a turn...IMO steering geometry has a little to do with it" Rick, you are wrong. Steering geometry has everything to do with it. Increase you front sag (decrease preload) while simultaneously decreasing rear sag (increase preload), your bike may turn so quickly so as to become unstable. Do the opposite and you will find that you will need to excert constant and increased effort all the way through a turn or the bike will try to stand up. Just raising my forks 1/4" made a drastic change in the steering on my M2. Where it was previously heavy and slow wanting to stand up in turns it is now light and quick and perfectly neutral tracking through a turn. Others here have had the same experience. The moto mags also confirm this, especially the racing rags that cover such things in detail. | ||
| Blake |
Proponents of gyroscopic precession as a mechanism to steer/turn a motorcycle, Some interesting facts about gyroscopic precession... When the precession and spin axis are orthogonal (at a right angle to each other) like on a motorcycle, the equation of angular motion reduces to... where... Mx is the applied moment about the X-axis (steering axis in our case) causing the precession. I1 is the gyroscope's (wheel/tire assembly's) mass moment of inertia about the spin axis (Y-axis or axle in our case). f' is the angular speed of precession (rate of leaning in our case) about the Z-axis (longitudinal axis of bike in our case). g' is the angular speed of spin of the gyroscope (wheel/tire assembly in our case) about the y axis (axle in our case). What does that equation tell us? 1. The gyroscope precesses about an axis perpendicular to both the spin axis and the moment axis. We already agreed on that I think. 2. The rate of precession (f') is inversely proportional to the rate of spin (g')for a given moment (Mx) acting on a gyroscope. In other words, as the front wheel on a motorcycle spins faster, gyroscopic precession becomes less and less effective in getting the bike to lean, (the bike leans more and more slowly). What this also means is that for higher speeds on a motorcycle the effort required to get the front wheel to precess and the bike to lean increases proportionately with the speed, or the bike become harder and harder to countersteer as speed increases. 3. Large moments are required if the orientation of a rapidly spinning gyroscope is to be changed. What this means is even just getting the wheel to turn takes significantly more effort at higher speeds. End of discussion? Or do you want to refute the basic theory of dynamics? | ||
| Rick_A |
M2...It's just my opinion that there's a world of difference between putting around a parking lot and riding a bike at speed. Blake, about the steering geometry issue...I've experimented with setups and it seems to me that changing the geometry increases/decreases steering effort (front end stability) but is fairly independent of actual turn in (lean) effort. About the steering effort thing, are they really trying to reduce steering effort or decrease the possible steering radius? Ultimately they're trying to build a stable machine that'll turn the tightest possible radius at speed. I still stick to it...sure countersteering effort increases, but gimme a break...on a modern sportbike unless you're a competitive roadracer or a real wimp what real difference does it make? Hell, the Firebolt is known to have a higher steering effort than all current Buells...doesn't seem to be that much of a hindrance, does it? It still runs circles around just about any current street machine. The theories are simple. When it comes down to it you're throwing out that info to try to prove your opinions. Significant to you=a bit harder for me. Okee dokey?  | ||
| Blake |
Rick, "I've experimented with setups and it seems to me that changing the geometry increases/decreases steering effort (front end stability) but is fairly independent of actual turn in (lean) effort." So you think that steering geometry does affect steering effort but does not affect the effort effort required to steer? Huhwhajusay? I think I'd say that you are half right.  " are they really trying to reduce steering effort..." Yes. Better handling means easier steering means reduced steering effort. You would be astounded at the effort expended by motorcycle roadracers in getting their machines turned at high speeds. "sure countersteering effort increases, but gimme a break...on a modern sportbike unless you're a competitive roadracer or a real wimp what real difference does it make?" I agree. The discussion is/was centered on whether gyroscopic precession helps or hinders the ease of steering a motorcycle. "The theories are simple. When it comes down to it you're throwing out that info to try to prove your opinions. Significant to you=a bit harder for me. Okee dokey?" No. Actually I am not offering opinions. I am offering truth. I support that truth by facts born out by simple physics and simple logic. I mean how absurd is it so say on one hand that the gyro action of motorcycle wheels at high speeds helps to stabilize, then on the other hand offer that the gyro action helps improve steering response, a condition depending on a temporary lack of stability. The extremely simple equation offered above lays it out in simple terms that cannot be refuted. | ||
| Grizzlyb |
Hi Blake, I countersteer my bike in many short/fast corners up to 60 mph. Even at higher speeds when the left/right corners are following each other quickly. On fast tracks like that, I can't shift my weight fast enough without shaking the bike to much. Just throwing my bike under me to the left and right side it much more easy to get through the corners. It requires lots of practice and skill, but in the end it will pay off. Just for practice I did this while riding in the group in the Rockies. Many times we road corners faster then 60 mph. Not once I leaned in the corner and I wasn't slower then the rest :+). Actually you can (dont have to) use this technique always. Only under race conditions you really need to hang of the bike to get more ground clearance. Think about it, You are going around a corner at high speed. You hang down your bike real close to the ground. The real wheel counters some dirt or oil. You feel the rear tire loose contact. It will be very hard to get your weight up again in time. In this situation it will be very hard to get out of this tight spot. Siting in upright position and just angling the bike under you, It's much more easy for me to shift my weight a little and get the bike back under my control. I hope I explained it clear enough. Its hard to explain it without showing it. ciao Grizzly | ||
| Aaron |
Brian and I went out flattracking a few weeks ago. This was my first experience at it. My natural tendency was to hang off the bike to the inside. Well, I have a hole in my left knee and one ruined pair of jeans to show for it, after a low side. Brian's style was more classic flat track, sit upright and lean the bike. He crashed a couple times too, but, he was noticeably faster than me. I gotta unlearn what I know and go learn his technique. | ||
| Blake |
Griz, Like you, it is rare when I hang off riding on public roads. Like you say, it is a technique only to protect from dragging hard parts. At speed however, I find that leaning forward and inside just prior to initiating countersteering is the most smooth and efficient way to attack a curve. I also agree, if the bike starts to go out from under you, it would be better to be sitting on top to have a chance of saving it, either that or to already have a knee dragging like the racers do. I sure have enjoyed the video of you and Peter riding in Colorado. Too bad the ride/video got cut short.  Aaron, Ouch! Pictures? ![:]](http://www.badweatherbikers.com/buell/clipart/proud.gif) Was Brian using his "shoe"? | ||
| Kerryx1 |
Dug out some "old" pictures of me during the flat track days and really studied them. My style tended to be fairly straight up leaning the bike way over sliding. Depending on the line in the corner and how rough the surface was there were only three contact points between me and the bike. Both hands and right foot on the peg, left steel shoe sliding and air space under my butt to allow the bike to dance around trying to find the line. Always wondered why my right leg bothered me the most! It's obvious where all the pushing to keep the CG of the leaned bike was coming from. Love coming out of the second and fourth turn in a tuck, both feet up, still sliding sideways and the front wheel six inches off the deck! Aaron...HeHeHe! You've got to put some ballast on his boney little butt to handicap him. Going fast is his genetic makeup! Best of luck to you and Brian in the upcoming year!  Blake...You're unbelievable! Now when I'm out in the twisties, all these formulas will be running through my mind! Glad I can apply them without a thought process otherwise the training wheels go back on! Lots less confusing matters in drag racing. Only have to contend with the coefficient of friction and turning "turtle". Wishing the absolute best to all of you out there in this wonderful world thats been graced with Erik Buell's dream come true! 'Ole Baldie  | ||
| Blake |
Here's another interesting analogy. When running or walking in what direction do you first place your lead foot when initiating a sharp change in direction? Answer... In the opposite direction that you wish to turn, just like countersteering. Where's the gyro? The reference for the case of the counter-rotating gyro on the front wheel is... D. E. H. Jones, “The Stability of the Bicycle”, Phys. Today 23, 34-36 (1970) Okay, even though we've proved conclusively that gyroscopic precession hinders the turning of a motorcycle at high speeds, let's do some more calculating to compare the relative effects of gyroscopic precession versus just plain old f=ma resulting from a steering input. Let's look at the case where a motorcycle and rider are traveling straight and upright at 70 mph and then inmput a "bump" to the handlebars that imparts a 1 degree resultant steering input. What happens? At velocity (V) equaling 70 mph, we would be traveling at 70*5280/3600 FT/S = 102.7 FT/s = 31.29 m/s. Let's assume the handlebars are suddenly "bumped" into rotating so that the front wheel changes its heading 1.0o clockwise (CW) about its vertical axis as viewed from above. The front wheel would then have a component of its velocity aimed to the right. That component will be approximately equal to 70 mph times the tangent of 3.0o. TAN(3o)=0.05241, so the transverse component of velocity will be 0.05241*70mph=5.381 FT/s. And we know that as soon as this input is enacted, the rear wheel will commence to follow thus immediately causing the bike to change heading, thus quickly amplifying the transverse component of velocity far beyond the initial 5.381 FT/s. Well, I think you can see that with the front wheel accelerating so quickly to the right, the resisting inertia of the bike/rider will cause the bike/rider to quickly tip to the left. The effect is akin to pulling a rug out from under someone. Moe later... Here's a decent High School level Physics reference with lessons and solved problems | ||
| Sarodude |
First let's get off the semantic issues. A lot of what I'm reading is 2 people TRYING to say the same thing using different words. Strictly interpreted, the ideas differ. I don't really think that's what we're trying to do. Another thing that seems to be muddying up the waters is different ideas of 'hard' or 'tight' turns. A tight though low G turn requiring a quick transition into the turn is something entirely different than a higher speed and / or higher G turn or one getting closer to the limits of adhesion and / or cornering clearance. Sometimes it's more important to transition in / out of a turn quickly and perhaps give up some ultimate cornering speed / G / clearance / whateverdeflatesyourboat. Other times you're in a long, high G turn for an extended period. Most of the time you're someplace in between. These are just my observations of your observations. -Saro | ||
| S320002 |
'Actually I've never found it sooo difficult to get a bike to lean at high speed. Unless of course I try do it without counter steering.' "You have GOT to be kidding me. Apparently you have never ridden aggressively around a twisty roadrace track or attacked a set of high speed S-turns with vigor or even simply attempted a quick obstacle avoidance maneuver at high speed." Blake, That's a joke right? Road race tracks I've ridden around aggressively: Laguna Seca, Sears Point, Firebird, Willow Springs, Streets of Willow Springs, Black Hawk Farms, Road America and a few others. Do any of those count as "twisty roadrace tracks"? Does dodging exploding semi tire treads at 80+ mph count as a high speed avoidance maneuver? I'm not a roadracer, but I'm no virgin either. If you've ever watched the pro racers throw their bikes through the Corkscrew at Laguna Seca you would understand why they get arm pump, and it isn't from "lean steering". Of course putting on the "air brakes" by sitting up just before most corners could have something to do with it too. Blake you really need to quit trying to prove everything on paper. The real world is just on the other side of that page. High School level Physics is what lead you to some of those silly conclusions. Greg | ||
| Rick_A |
No, I think steering geometry affects stability and the initial steering effort but not the effort required to lean the bike thereafter.
It's a balance they're trying to achieve. Stability, reduced steering effort, and a "tight" geometry. There's always compromise. | ||
| Blake |
Greg, "That's a joke right?" If you actually believe that the steering of a motorcycle does not become increasingly difficult with speed, then your opinion is the only "joke" here. If indeed you have ridden aggressively on racetracks like Laguna Seca, and have not noticed how difficult it is to force a motorcycle at high speed to quickly dive into a turn or to quickly transition from a left to a right hand turn, your credibility has flown out the window and died. "Blake you really need to quit trying to prove everything on paper. The real world is just on the other side of that page. High School level Physics is what lead you to some of those silly conclusions." So you disagree with the laws of physics? Why am I not surprised.  The best science is simple science. You can poopoo it all you want. It is simple fact. I'm sorry you cannot grasp basic physics, or are too in love with a myth so that your ego cannot let it go. Unlike you, my experience in the real world confirms the very behavior that simple physics predicts. Turning a motorcycle aggressively becomes increasingly difficult at high speeds. Here's another example for you, Greg. Ever see a suitcase gyroscope? It looks like a small ordinary suitcase or briefcase. It contains a very powerful, high speed gyroscope that when energized by internal electric motor spins at high speed in plane with the case's seam. Energize the case as it sits upright with handle on top. You can then walk up and pick up the case and continue on walking in a line parallel to the case. Try to make a 180o turn in either direction. What happens? If you are not careful, you will twist your own arm right off. The case will not turn. Set the case down and try to force it to turn by pushing/pulling on opposing ends. You will nearly herniate yourself trying to get it to turn, and as you do so, the case will, very very slowly begin to lean and very very slowly begin to rotate. Once you stop pushing/pulling on the ends of the case, it will maintain its same lean but will continue to rotate. You see, a gyroscope is a repository for angular momentum, and just like how a two ton block of lead that is sliding slowly along on a flat sheet of ice will robustly resist any change to its speed or direction of travel, a gyroscope likewise will robustly resist any change to its angular speed or the orientation of its axis of rotation. What you believe is akin to claiming that you can nudge that 2 ton block of lead and get it to change course by a significant measure. Where mass times velocity (mV) quantifies the magnitude of momentum in a linear system, angular velocity times inertia (wI) does so for a rotational system. There is nothing magical about a motorcycle that renders the laws of physics moot. Gyropscopic precession is what we are fighting when we try to countersteer, lean and turn hard at high speed, it certainly is not helping. There are two subtle ways in which gyroscopic precession could be seen to benefit the handling of a motorcycle. 1. The gyroscopic stability provided by wheels and engine are of some benefit. Gyroscopic effects are in no way required for stable riding of a motorcycle, but none the less, gyroscopic effects do stabilize a motorcycle. After all, that is what gyroscopes do. Unfortunately it is the wheels' propensity to conserve angular momentum that also makes it increasingly difficult to maneuver quickly at high speeds. 2. When leaning a motorcycle into a curve, after the countersteering input is finished, gyroscopic precession does definitely help turn the front wheel back into the direction of the turn. It does so secondarily to the effects of trail, but it indeed does so. | ||
| Blake |
Rick, "No, I think steering geometry affects stability and the initial steering effort but not the effort required to lean the bike thereafter." Steering effort and leaning the bike are one in the same. You cannot separate the two. Actuate left, lean right, then actuate right to maintain lean and actually turn right, then actuate right to recover to upright then actuate left to stop recovery. When you make a turn, the steering input looks like...  Steering Angle Versus Time in Turning a Motorcycle at Speed At higher speeds the gyroscopic effects come into play and make turning difficult no matter your steering geometry. There is where lightweight tires and wheels come into play. The smaller the trail the quicker the steering. Quicker steering meaning that for a given steering input the bike turns more sharply and thus more quickly. You actuate the handlebars less to accomplish the same turn. Saro, Yes, there definitely needs to be a balance. A bike with zero trail may turn easily, but it will not handle very well. Reducing inertia of the wheel assemblies is a big concern for racing team engineers. | ||
| Xb9er |
Blake said: Let's say I just completed braking and start going into a decreasing radius right hand turn at a speed of about 50 mph. I initiate the turn (press right to lean right) and I smoothly roll on the throttle and steadily accelerate through the turn. Now midway through the turn, I find I need to tighten up the turn, so I slightly nudge the right bar (again press right to lean right) to increase the lean angle and end up exiting the turn at, for example, 75 mph. I personally find it pretty much effortless to increase lean angle when going fast. I normally go into turns completely tucked and hugging the airbox, with my shoulders just slightly forward of my elbows and my forearms level with the grips. So there is no strength there. In fact, my fingers are loosely wrapped and my left hand just rests on the grip enough to get feedback and my right hand is completely relaxed but firmly gripping the throttle. I've never been on a racetrack. I am not an expert rider by any means. I don't think it feels effortless to me just because of the Firebolt's steering geometry, etc., it should be the same on any modern sportbike, at least I think so. Sorry I can't give a technical explanation (I was just glad to pass Physics classes). If I misunderstood your statement let me know. You're not talking about a situation where you have all kinds of room (like an empty airport runway for example) and you're going about 100 mph then try to turn hard without any braking, or are you? I've never tried that so I honestly have no idea how hard it would be. Blake also said: Pardon my ignorance again. I thought about getting out and trying this, but a voice inside told me that if I turn the bars into a turn I would surely crash. If I did what you are saying (press right to lean left or press left to lean right), the contact patch of the front tire would move forward and in until eventually I would steer the front tire right out from under me. In my limited experience, it seems that the bike's tires want to track straight, so I stay relaxed and I let the bike do the work. How much force are you exerting on the bars to turn in the tire? Is this a racing technique or does it apply to all riding? Again I haven't been on a race track. I am just telling you what I see and feel when I ride in the real world. Any comments welcome, but after reading over and over again what's been written about the physics behind it all I still can't grasp it, so go easy on me. Thanks for listening. Mike. | ||
| Jprovo |
http://www.eurospares.com/tfoale/book/Turning.PDF Some more fuell for the fire, I haven't read it in full, but I'm going home. I'll read it there. Happy new Years, James | ||
| Davegess |
Blake I have to diagree that hanging off the inside is ALWAYS the fasr way around a road course. Most turns sure. BUT if you wantta bacj it in you better be on top of the biek or you are gonna get hurt. Now the dirt track boys ALWAYS back it in and not at some wimpy 70 mph either. Turn 3 at Springfield has an entry speed more like 130mph. The road racers only back it in once in a while cause it will toast your rear tire in a hurry but I have seen Ben Bostrom and others use it at Laguna to pass guys they had no other way to pass. A couple of years a go BB actuall spent most of a practice session finding how late he could go into a particular turn, forget which one, He would drive in deep, back it in and if it worked next lap he went deeper. Finally had to stand it up and take the escape route. He passed the same guy at that spot twice in the closing laps. Seonc time it stuck. He scraced the xxx out the fellow the first time he did it. The other difference between the RR and DT guys is that the RR guys have to do it to a much less dramatic degeree tha the DT guys so it is not real obvious when they do it. And than thay can only do it 2-3 time a race or the tire is cooked. Dave | ||
| S320002 |
Blake, "Steering effort and leaning the bike are one in the same. You cannot separate the two." Does that mean if I coast to a stop and don't make any effort to steer or put my feet down my bike won't lean? You've really got me giggling now. Happy New Year! Greg | ||
| Peter |
Mick disagrees....  | ||
| Davegess |
i'd say Mick is exiting not entering that corner Peter. | ||
| Jprovo |
Blake, your graph shows steering angle, and you say steering input. I agree with the steering angle graph, but I belive that the steering input would look quite different. Too bad that there wasn't more of Tony Foale's chapter online... Guess I'll have to buy a copy $$$ James | ||
| Lornce |
You lads my enjoy the Motorcycle Chassis Mailing List hosted at majordomo. Tony Foale's a regular contributor, and is very gracious with his time and knowledge. Fairly international crowd: Euros, Aussies, Canadians and Americans too. | ||
| Lornce |
Whoops. The Motorcycle Chassis and Design mailing list, mentioned above, can be found and subscribed to at www.micapeak.com. Best of the New Year to you, Lornce | ||
| Rick_A |
Blake, I know all of that...it just seems like after the actual countersteering event...independent of all other factors here...once the wheel is pointing towards inside the turn, the bike will basically steer itself according to the degree of lean...and that lean effort isn't affected much by steering geometry. I know a lazy geometry generally isn't capable of holding as tight a line as a quick one...and the countersteering effort and time is greater...but that's not what I'm talking about. | ||
| Blake |
Mike, Very well put. Actually yes, 50 mph may not be quite fast enough to readily feel the death grip of angular momentum on the turning capability of the bike. And yes, I am referring to a situation where the rider is trying to turn the bike aggressively. As to turning the wheel into the curve once the countersteering gets you leaned over. This is something that we usually never notice. If you pay very close attention when turning you will notice that the wheel does indeed turn into the curve. It may require no effort on your part due to trail and the purposefully designed stable steering geometry. The plot I show above is accurate. To initiate a hard left turn you crank the bars to the right. As the bike leans, you let off and allow the bars to turn left, into the curve. If the front wheel failed to turn into the curve once leaned over, the bike would continue to tip over until it hit the ground. This has all been documented through instrumentation telemetry systems mounted on test vehicles. It is the same for motorcycles as it is for bicycles. There is no difference, regardless of what some say, between the physics of a low speed turn versus a high speed turn. Both are accomplished in the same way, via countersteering. We walk and run in the same fashion. A slalom water skier skis in the same fashion. We always must first go left to initiate a turn to the right and vice versa. I have been at 100 mph and tried to execute an aggressive series of "S" turns. The handlebars felt like they were constrained, it felt like the steering head was seizing up on me. Imagine what it would feel like at race pace. Try riding on the very edge of a line, just to the left of it. Try to execute a left turn without leaning and without crossing the line. You cannot. If you turn right, the bike goes right. It leans left, but it most definitely goes right. It only goes left once the front wheel is turned left. It is the same as if you are walking briskly on a straight line, now try to commence turning quickly but smoothly in a tight arc to the left. What happens? Your right foot gets planted well to the right of the line. You had to go right to initiate a turn to the left. The gyroscope stuff is not intuitive at all. Best thing to do there is get one and play around with it to get a feel for what precession really is. Even after understanding the principles behind it (conservation of momentum) gyroscopic action is still like magic to me. The best teacher of all was the briefcase gyro demonstration I mentioned above. It was actually very funny to witness. The poor hapless volunteer that got picked to walk the gyro-case just about broke his arm trying to get the thing turned. When he went to turn around and walk back to the science guy running the show, he let out a yell and dropped the case on the stage floor, BAM! He could not believe the reality of it. I think his name might have been "Greg." Hope that helps. | ||
| Blake |
Greg, Ever heard the saying "Better to appear a fool and say nothing rather than speak and remove all doubt"? Ooops. Too late. Happy New Year. |
