| Author | Message | ||
     Blake |
Mr. Foale is another who professes faith in the mantra of the magic gyro. | ||
| Blake |
James, The graph is meant to portray the angle of the front wheel wrt the longitudinal axis of the bike. I'm not sure what distinction you are making between "steering angle" and "steering input." I guess you are thinking that one is at the front wheel/tire about an initially vertical axis, and the other is at the handle bars about the steering head axis. Dave, Even when backing it in I think most competitive road racers are still hanging off to the inside, aren't they?. I think Gary McCoy was the most recent flagrant user of that method that I've ever seen. BBoz is a close second. Of course Kenny Roberts made it an art form. Of course none of that has anything to do with hanging off the wrong side while putting around a parking lot. In my mind, and in my experience, "hanging off" is what Mick is doing in the pic above that Peter posted. Thanks Peter. Great Pic. | ||
| Peter |
Dave, Actually I just wanted an excuse to post that pic, but I've also seen Mick back it into a corner like that and then just steer the whole corner with his throttle. The best bloke I've ever seen do it though is Anthony Gobert. Blake, No problem. I also happen to disagree with you. I use the outer edge of the seat style of riding ("hanging off" for semantic purposes) at times. It gives me better bike control in some situations. Carparks being one of them. PPiA | ||
| Grizzlyb |
Hi Pete, Great pic mate, if only we had enough sponsors to let us play like that. Happy new year, Grizzly | ||
| Kerryx1 |
>>>>"We always must first go left to initiate a turn to the right and vice versa."<<<< Wisdom does come with age! That's why all the senior citizens driving a "cage" in my area negotiate such a large hook shaped arc like they're towing a 53' trailer to make a simple turn off the highway! Like bumpers on a pool table, every action requires an equal and opposite reaction. As I walk around my house this morning like a billiard ball bouncing off walls to change direction, I laugh like hell picking myself up trying to prove Blake wrong! Happy New Year you big Texas oaf! Glad you love Buells almost as much as formulas!!!!  'Ole Baldie | ||
| Blake |
heheheh. Alright guys. You win. If sitting upright and or scooting a bit to one side is considered the same thing as hanging off, then I'll have to agree too, it aids low speed maneuverability a bunch.  Hmmm, sixty degrees F, bright and sunny. I think I'll go for a ride. Maybe have Keith take a bunch of pictures of me doing figure eights in the parking lot. Will probably reveal I'm not leaning. I do know a little about hanging off, too much fun!  ...  Motorcycle Dynamics in Action (Turn 7 at Oak Hill Raceway) The above pic was taken about 100 meters past where X1Glider decided to explore the native terrain. The telltale scars of his excursion back in October are still glaringly evident where the sod and cactus have been plowed up to expose the red East Texas clay. Henceforth Bob's X1 shall be dubbed "The Landscaper." ![:]](http://www.badweatherbikers.com/buell/clipart/proud.gif) Blake (firm believer in the validity of M=f'g'I) | ||
| Blake |
One more quick note... For Rick... For Greg...
There ya go Greg. Giggle away my friend. Then I'll tell you who authored those statements. Any guesses? Anyone? Blake (fixin' to prove once again that basic Physics doesn't fib) | ||
| Peter |
Griz, I've just been watching the start of the Paris-Dakar. Interested in doing it? I'd have to sell the S1W to pay for it though.... Happy New Year 2U2. Blake, Tony Foale? Erik Buell? PPiA | ||
| Rick_A |
Great Blake, now tell me something I don't know | ||
| Blake |
No, Tony Foale is a strong believer in the myth of the magical motorcycle gyro. It wasn't Erik either, though I am sure he concures. | ||
| Grizzlyb |
Pete, I AM interested in the PD. Also looking for sponsors to do that. We had enough practice to pull a stunt like that :+. Blake, The GEEK ? ciao Grizzly | ||
| Jima4media |
Blake, What does Tony Foale say that you disagree with? http://www.tonyfoale.com/book/Turning.PDF | ||
| S320002 |
Blake, Not to worry. I'm still giggling. As usual you have tried to ignore or misdirect everything in my posts that doesn't agree with you. Simple physics is just that. It is full of frictionless bearings, volumeless masses and formulas which ignore higher order effects. Using your High School level physics can you explain how a bumble bee is able to fly? Also you haven't answered my question. According to your simple physics, if I don't try to steer or move I shouldn't have to put my feet down at a stop. Does the real world really work like that? No matter what your simple physics equations tell you I'm still going to put my feet down. Don't take it too hard. I knew a guy who designed an extension for a 30 ton crane, it worked perfectly according to his calculations. The real thing collapsed in a 10 mph crosswind. Greg;-) | ||
| Blake |
Jim, From a post you made last year... "...the actual counter-steering movement is very small, since gyroscopic precession depends for its strength on the speed of movement not on the amount of movement." All bow to the magic gyro.  Tony seems like a smart guy. Maybe by now he's discovered the folly of the magic gyro steering bike myth. | ||
| Blake |
LOL! Yep, in fact he proves it in the excerpt to which you provided a link. Apparently now, after doing some computer simulations ole Tony finds that with gyro effects only at a speed of 63 mph (100 kph) on an average street going motorcycle, it would take a steering input of 45 degrees and 41 FT-LB's (56 N-m) of peak torque applied to the handlebars to attain a lean angle of 40 degrees within 1.2 seconds. He says he took out the tires' lateral constraint. He didn't say he removed gravity though. That would make the results even worse. Forty-five degrees of steering input! LOL!!! Try that at 63 mph and see what happens! He apparently cannot let go of the myth, even after his own research shows it to be ridiculous. | ||
| Blake |
"As usual you have tried to ignore or misdirect everything in my posts that doesn't agree with you." No. I offer explanation, example, and proof. Don't know how you get misdirected from that. I guess I can see how logic and science could misdirect you from your fantasy world of magic gyro motorcycles. You on the other hand throw out evasive rhetoric. The author of the above posted quote, the one stating plainly that "at high speeds, gyro effects slow the steering down" is none other than Mr. Kevin Cameron. The quote is from his Sportbike Performance Handbook. I don't know anyone more credible. "Simple physics is just that. It is full of frictionless bearings, volumeless masses and formulas which ignore higher order effects." A gyroscope is a pretty basic mechanism, a spinning disk; gyroscopic dynamics are perfectly understood. The physical relationships describing the behavior of a spinning gyro are infinitely simpler than those needed to describe the flight of a bumble bee. Physics is full of "formulas which ignore higher order effects"?  Please name two. Formulas do not ignore higher order effects; people do. The concept of friction, by the way, is also basic physics. If you choose to ignore it, that is your doing, not the science. Likewise the concept of volume, by which I interpret you to mean "inertia", is also an extremely well-understood basic physical phenomenon. If you choose to ignore it, that is your doing, not the formulas'. Greg, you have yet to offer one single minute fact that refutes the basic equation of gyroscopic motion posted above. Neither have you addressed the myriad of logical conclusions or examples I have offered. Such obstinance in the face of overwhelming and conclusive proof is bewildering. Who is the one doing the misdirecting here? Not I. "Don't take it too hard. I knew a guy who designed an extension for a 30 ton crane, it worked perfectly according to his calculations. The real thing collapsed in a 10 mph crosswind." Greg, I'm not taking anything about this debate "hard." I'm extremely satisfied knowing that sooner or later you might be enlightened to the truth. As to the guy you knew who designed an accident waiting to happen... Big deal. So what? People make mistakes. The guy made a miscalculation or overlooked something. Shit happens. Are you implying that an engineer's screw up should indict the validity of the well proven basic laws of physics? Restated in plain English... The required amount of torque or moment (M) applied through steering to generate a given rate of gyroscopic precession/lean (f') in a motorcycle's front wheel assembly that is spinning at a speed g' and has an Inertia (I) is equal to the product of the rate of precession (lean), the speed of rotation, and the inertia (M=f'g'I). Solving for the rate of precession we get... Of course I am ignoring the additional effort (applied moment) that would be required to cause, not just the wheel assembly itself, but the entire bike to lean; that very significant additional applied moment is proportional only to the rolling-axis inertia of the bike and the rate of lean; it is independent of the bike's speed and so can be neglected as applies to our discussion. Please show me where the above is wrong. By the way, how do you think we were able to pull off the Apollo missions? I guess all that unreliable basic physics held up okay back in the 1960's, but now it just cannot be trusted? I dunno, you may be hopeless. I may be banging my head against the proverbial wall trying to offer the truth to you. Almost seems as if you have a chip on your shoulder for engineers and the like. Doesn't make sense, since I assume you are one too. I've had dealings with many like that. You probably have too. Ego, it's a terrible thing to waste. So what's up? If you are so sure that gyro action is what is turning our motorcycles, how about contributing something along the lines of, oh I don't know, evidence? It ain't rocket science. What do you think of Tony Foale's simulation results? Does it support or refute the magic gyro theory?  | ||
| Blake |
Anyone have a copy of his book. How much you want to bet that the no gyro simulation shows a minimal steering input, somewhere less than 5 degrees, and a much quicker lean. Any takers? I don't know why he says that such simulations are not possible in the real world. They certainly are. Especially the case for zero gyro effects. It's been done on a bicycle's front wheel already. Ferpetesake, the guy is a degreed electrical engineer turned nuclear who then became a structural engineer? No wonder he's so confused. heheheh | ||
| Jima4media |
I was just looking at what we had written last year on this subject. I guess this topic always comes up in the winter when we aren't riding as much. I wish I had Tony's book, so that I could read the "appendix describing the mechanisms of gyroscopic effects" I saw it at Laguna Seca, but couldn't fit it into my bike bags for the trip home. Haven't seen it since. There is a software application called Mathematica from Wolfram Research that could probably model these things pretty well, and show it in 3D animation. http://www.wolfram.com Have you heard about Stephen Wolfram's new book - The New Kind of Science? Most interesting. Jim X-2.5 | ||
| Blake |
Notice in Tony Foale's gyro only simulation that the torque peak occurs at a relatively small steering angle? Double the speed of Tony Foale's simulation motorcycle to 125 mph and you get a required input torque of 82 FT-LBs. Now cut the time to lean in half and increase the lean angle to 60 degrees. I'd say about 160 FT-LBs sounds about right. Roadrace clipons have a spread of what about 1-1/2 FT? At 160 FT-LBs and 1-1/2 FT, you would need to push/pull with 53 LBs of effort on each handgrip. Can you say arm pump? Can you say, gyroscopic action sucks at high speed? At high speeds, the gyro action tries to run you straight into the wall. That's not helping matters in my book.  | ||
| Jima4media |
That's why it is good to slow the motorcycle down before you get into the corner. That way you lessen the gyroscopic effect, flick it into the corner with less effort, minimize arm pump, and you are ready to drive hard out of the apex. You don't need to understand the second law of thermodynamics or the second law of motion to ride a motorcycle, but it helps you get through the boring winter nights. It all works if you do it correctly, with the right equipment. | ||
| Blake |
Yes, it is a good winter discussion topic for sure. I was hoping to finally put it to rest though. Maybe we could get Erik Buell to address the topic in the next issue of Fuell. Here's another related thought provoking qquestion... What happens when you apply a steering input (M) to a gyro, that is restrained against rotation about the precessional axis? | ||
| Blake |
Jim, I was tempted to order Tony's book and CD from his web site, but the price scared me away. Sure sounds like he's done a lot of thinking about the issue. Seems like he may have finally realized the truth wrt gyroscopic effects, but is having a hard time admitting the error of his prior beliefs. A 45 degree steering input??? LOL. | ||
| Jima4media |
Here are a bunch of good references about what we are really talking about. This is the best that I can find on the internet. http://scienceworld.wolfram.com/physics/Acceleration.html http://scienceworld.wolfram.com/physics/CentripetalAcceleration.html http://scienceworld.wolfram.com/physics/SecondLawofThermodynamics.html http://scienceworld.wolfram.com/physics/GyroscopicPrecession.html http://scienceworld.wolfram.com/physics/MomentofInertiaRing.html http://scienceworld.wolfram.com/physics/MomentofInertiaCone.html http://scienceworld.wolfram.com/physics/RotationalStability.html http://scienceworld.wolfram.com/physics/Friction.html http://scienceworld.wolfram.com/physics/NewtonsLawofCooling.html Some of these are included for the Physics of a Stoppie discussions. Jim | ||
| Davegess |
Blake, I was always taught, and have done this sucessfully, that if I am going to run wide on a turn to PUSH harder on the opposite bar and the bike will turn more. Push left to turn left. I always thought I was upsettign the Gyro more thus making it lean more and turn tighter. What is actually happening. As far as backing it it, go take one of the AMericna Super Camps. Loads of fun, makes you faster on the track, more in control on the street and JUST LOADS OF FUN. You spend all day every day sitting on top of the bike backin' it in. You start to think you are getting OK at at it than Chris Carr or some other nome guy shows up and you realize just how hopeless you are  Dave | ||
| Jima4media |
Brakes? We don't need no stinking brakes! Just modulate the throttle and steer with your rear wheel. I just love watching flat trackers do that at 100-140mph. | ||
| Rick_A |
That increased effort is why I like running low clip-ons. Ride with high clip-ons (IE, bars above the top triple clamp) and then low ones (below the triple tree). I find it's a lot easier to steer with all that weight on the bars...or is it just me  ? | ||
| Reepicheep |
I was going to try and answer Dave's question, but as I typed it I just got more confused. Could somebody explain the physics of a high side, particularly how the gyroscopic forces come into play? I think that might help a lot of our understanding if the same forces are at work, but just to a different degree. I am thinking of a sudden highside where the bike goes totally airborne and does several flips before ever even touching the ground again. Are there gyro effects here? seems like there must be, and not a simple pole vault. | ||
| Rick_A |
I think the fact that the bike will usually flip in the plane of the wheels once airborne demonstrates that. | ||
| Blake |
Jim, The 4th link you posted, the one about gyroscopic precession, addresses the case where you have a gyroscope acted upon solely by the forces of gravity. It explains the behavior for example, of a spinning top as it begins to tilt and precess. The behavior of a motorcycle's front wheel due to an applied torque (we've been calling it a moment) normal to the axis of spin is perfectly described by the equation M=f'g'I. What is the difference? Dave, "What is actually happening?" As long as you are not sliding, the dynamics of mid-turn corrections are no different that those of turn initiation. In mid turn, by initially steering in the wrong direction (countersteering), we cause the tires to track away from the bike's center of mass. When initially upright, the bike starts to lean into the curve; if already leaned, the bike simply leans into the curve more. When the bike leans more, you can then turn more sharply into the curve thus avoiding running off the road. Consider that if in such a case, your tires were at the very edge of running off the asphalt on the outside of the turn, pushing on the left handgrip would put your tires off the road. Reep, "Could somebody explain the physics of a high side, particularly how the gyroscopic forces come into play?" That's a great topic/question. I'll try to answer it clearly. Most of us have probably experienced or witnessed a panicky rear wheel lockup where the rear of the bike proceeds to get out of shape or as we say "come around." Our instinctive reaction is often to immediately let off the rear brake. What happens then? When the once sliding rear tire suddenly regains traction, it throws the rear of the bike violently back onto its natural track, following the path of the front wheel. This is not a gyroscopic effect. This is the rear tire sliding off course then regaining solid traction and, just as a hard forceful turn of the front wheel can violently roll a bike onto it's side, the rear wheel violently forces the rear of the bike back into line. If the rear end has come far enough around, the magnitude and speed of the reaction can separate rider from motorcycle. This scenario involves negligible lean; it can occur even when riding upright and straight ahead. If the rear tire breaks loose under acceleration with the bike leaned over, the effect when full traction is suddenly regained is similar. The orientation of the bike is just different, unfortunately it exacerbates the problem. When regaining grip at the rear tire when leaned over, the rear wheel, in its eagerness to get back on track, lurches violently towards the inside of the turn. Because the bike is leaned, instead of just moving the seat laterally, the seat is kicked almost directly into the rider who is most often hanging off inside. The effect is much like a horse bucking. Yeeeehaaawww! NOT! The rider, if unprepared, can be tossed up off the seat with only their hands left holding tenuously onto the bars to maintain contact with the bike. In that position, steering ability isn't ideal, so any manner of unwanted steering inputs can occur. Things can go from bad to worse very quickly. What physically is happening is that the sharp lateral recovery of the rear end causes a spike in the centrifugal force, the apparent force acting to push the bike to the outside of the curve. The momentary spike in the outward tipping centrifugal force far exceeds the inward tipping force of gravity. What was in equilibrium becomes violently unbalanced. The force of gravity that had been just exactly offsetting the outward tipping centrifugal force finds itself overpowered. The result is that the bike in addition to lurching laterally also tends to stand up violently. From the rider's perspective, as the bike is so violently bucking and standing up it does indeed become an effective catapult, much like the action of a vaulting pole being planted into the box and throwing the vaulter heavenwards. If the rider is lucky, or highly skilled, he can sense the situation and get himself up off the seat as much as possible, use his legs as shock absorbers and try his best to hang on as the bike slows and regains a stable track. Maybe we need a few diagrams? Anyone? Gyro action would tend to stabilize a bike at high speeds and would therefore tend to help mitigate a high side get off. The gyro action might allow errant steering inputs to be somewhat forgiven. How'd I do? | ||
| Davegess |
Anyone seen the video of Mamola? hanging on to a high side? He is tossed completly off the bike but hangs on to the grips. Takes several good bounces befroe he lands back on the seat. Pretty amasing to watch |
