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Rolling the throttle off doesn't reduce traction of the front tire, but increases the load on it. Exactly the opposite occurs with the rear tire during roll-off. The only way to reduce traction is by reducing the force that is perpendicular to the road (normal force). The transfer of weight onto the front tire increases that normal force, but also the lateral force. The ratio of increment of the lateral respect to the normal force is higher for bigger angles of lean. Skid will happen only when the magnitude of that lateral force exceeds the maximum allowable value (red circle in previous schematic). "Once the throttle is cracked on, it is rolled on evenly, smoothly, and constantly throughout the remainder of the turn." K. Code Regarding the effect of the roll-on: According to the book, the proper acceleration rate is 0.1 to 0.2 G. That means that for every second on the turn, the speed of the bike should increase 2.2 to 4.4 mph. That rule applies independently from the entry speed. Max lean angle will correspond with max speed; hence, your entry speed should be less to accommodate the gain in speed along the curve. The fastest you go, the quicker you will be done with the curve, and the difference between entry and final speed will be less. The opposite applies for slower trajectories.

Just focus on the important: http://forums.superb...p?showtopic=579 "If you think what I am saying is: you have to push through the fear barriers to get to clean riding, you are right; but the push comes after the understanding of where your attention should or should not be focused. .........There are basic principals to riding. What you ride doesn't change them. Where you ride doesn't change them. How fast you ride doesn't change them. They are what they are: they are not based on my opinions about them, they are based on well defined and easily understood basic principals you will understand. .........It has taken 30 years of devoted time and attention to separate the important from the unimportant and to figure out ways we can trick ourselves into giving up the resist-error-resist-terror way of doing things in favor of the focus-flow-focus-go mode............." Keith Code

There is the lean angle of the bike and there is the lean angle of the bike-rider system. The hang-off technique allows the latter to be higher than the former. Check this old post and schematic: http://forums.superb...indpost&p=26467 As you can see, the limit of traction (360 degrees around the contact patch) is reached only when the resultant lateral force on the patch grows up to the magnitude of the maximum static friction (force normal to the patch times the static friction coefficient). The lean angle of the system (bike-rider) is a visible gauge of the rate of those two forces: 26 degrees mean that the friction force is half of the normal force. The recommended 0.1G acceleration during a turn that Code recommends does subtract just a little of the maximum lateral allowable friction; however, it introduces a bigger benefit: to allocate a distribution of weight (40 front / 60 rear) that works in harmony with the design of the front and rear tire-suspension systems.

I really love your posts Mugget, but I would like you extending your explanation of the quoted statement. Here is a good article for the OP to read: http://forums.superbikeschool.com/index.php?showtopic=579

I am serious, indeed! My point is that, if done by the book, you will not be able to fall even if you push it beyond your current mental limit. In order to lean more and stay rubber-down you need to understand and conquer your fear. Riding that turn free of that fear, you will lean more, down to the physical limit, without experiencing the outcome that you fear now. Easier said than done, I know. This is not about motorcycling, this is about an irrational fear that bothers you and limits the performance of your bike. It is irrational because others passing you show you that the bikes can physically do it. The difference is that those riders do not interfere with the physics behind the process of taking a curve. They don't interfere because they have learned, in a classroom or by falling, that any fear they feel will create problems for the bike. Chapter 7 of A Twist of the Wrist II explains the whole thing very well. I have fallen due to the front, the rear and both tires and is not as bad as your mind makes you believe it is. Your survival reaction is nothing more than an exaggerated fear to an event that is perfectly survivable. Relax, my fiend, and just enjoy riding..........and even falling eventually.

Thank you all much; I am really learning from your interesting posts. Do you carry a safety factor into the curve, regarding entry speed? Like a special technique that you reserve for the case of an error for excess, traffic situations, etc.?

Just find the lean angle at which the bike will low-side. If you use the 40/60 rule for weight distribution and leave the steering bar alone, you may not be able to induce a low-side before the metal parts start scrapping the pavement. Have you fallen on a track before? Is really that terrible? This is like dancing, you have to flow, feel and enjoy. I can't see any joy in the face expression of those pictures.

Thanks, guys. Re-reading my previous question it sounds silly somehow. I believe that the reason of my question comes from my observations of that 180 degree turn in our local track, where I see riders (races and track days) not doing the visual technique (at least not in an obvious manner) and not following the line corresponding to a double apex turn. At least to my ignorant eyes, it seems that they run the interior of the turn and are stuck on the gas, except during the last 20 or 30 degrees of the turn.

Is this 2-step visual technique used in actual racing or track days? I ask because, in Florida track days, I have seen a lot of "riding around the inside edge of the corner", especially in turns close to 180 degrees.

As the discussion has evolved from selection of entry speeds to quick flick and turning points, how are those related to the Code's statement about the flick rate determining the entry speed? "Your quick turn abilities determine your corner entry speed. Period." For me it reads like this: You can turn the bike X degrees by either following a long radius turn or one or several very short radius turns. By quick flicking the bike, you can achieve a great amount of degrees of turn without going to extreme sustained lean angles.

Study the road via Google Earth before leaving

Thanks Johnny, very good response!

Some crash statistics from A Twist of the Wrist II: "Factually, it's uncommon to go into a turn too fast! Watch racing for 20 or 30 years and tell me what you observe. My eyes tell me going in too fast is low on the scale of crash causes. It is rare. Going in with the brakes on too hard and crashing is another thing; that causes crashes fairly often and is an obvious rider error. That most riders misjudge their turn-entry speed, usually on the slow side, is a major stumbling block to clean and quick turn execution."

Thank you very much, Hotfoot; my misconception is perfectly clear now. Sorry, it is hard for me to explain things in clear manner in English. I believe that your #5 question is the one. I only had one track day in the Novice group in Florida (not CSS); therefore, I am very ignorant about how picking an efficient entering speed is done for racing and more advanced track day's groups. The control riders made that selection for our group, and I felt comfortable and SR's free during the day. One thing did bother me at the end of that day: without the control riders, I would have been completely lost about how fast should I be rolling just before releasing the brake and flicking the bike. That was the main reason of my first post: I didn't know what was the proper technique to judge and reach an efficient and consistent speed for a particular turn under track conditions. Normally I don't make mistakes that trigger any SR while riding on the street, mainly because I have many years of experience judging street entering speeds and because the bike is moving far from its physic limits there. However, on a track, I will sure go in either too slow or too fast. Reading braking techniques in Code's book, I learned that initial hard braking allows the rider to fine adjust the entering speed. This speed is something precise and critical, I thought: a little low or a little high must be bad for the optimum track turn over a selected line. That is what made me wrongly assume that the rider would rely on some speed indicator for that level of precision. Thanks to everyone's responses, now I understand that the principle is the same than for street riding: practice, practice and more practice. Quoting Hotfoot: "Judging entry speed is an art....... it is something you need to be able to choose for yourself, on every turn you ride."

Thanks, Hotfoot. No, each case is different, unless all conditions are very similar, like in a high performance race. However, I believe that there is a physical limit that can be seen those racers hit. Certainly. Small, incremental ones. However, without looking to the speedometer, I believe that I wouldn't be able to do it in a stable increment, since small increments would be hard to feel. Yes to all. If subjectively too fast (actually doable but not according to my previous experiences), SR's will be triggered. If actually too fast and I do commit to the turn using correct techniques, tires will start skidding. Yes.

Thanks to all. I have been a street rider for long time; hence, I have a better idea for the street. Just by observing speed limits, the safety margin is huge. However, for track day (here in Florida), the Novice class was told just to follow the control riders, who were increasing the entering speed for each lap during the day. I just wondered, what references they followed to select an entering speed for each turn, since that was never explained to us. Reference points were explained and understood, but I felt completely lost about entering speeds.

I have finished reading Twist of the Wrist II, hoping to find an answer to this question, but either I missed it or is something obvious. Please cornering masters and more experienced riders, correct or comment on my two following assumptions: 1) I imagine that for a track, the rider is approaching the limits of traction for each turn, memorizing the maximum entering speed for each turn and observing the speedometer for each entering point. 2) For street riding, each new unfamiliar turn is to be entered at the speed that experience dictates for similar conditions.

Close; at 60 degrees the centrifugal force and tires' lateral grip are 1.73 times the static weight. 2G would be reached not far from 60: at 63.4 degrees. At those extreme angles, forces escalate quickly and things may go out of control soon; hence, proper throttle control there becomes more critical. "A motorcycle becomes potentially less stable as lean-angle increases......as we have seen, throttle-control plays a huge part in stability; the steeper you go, the better throttle control must be." - K. Code in TOTT2

You really look carefully, Crash106. Consider that the instrument measures the inclination of the frame respect to a vertical plumb (internal gyroscope). However, the actual angle that corresponds to the acceleration and force vectors is always smaller than the inclination of the frame, unless the rider hangs off enough to compensate that difference. This discrepancy of the angles comes from the off centering of the contact patches respect to the center line of the frame. In the video example, the bike has just rounded a corner with 34 degrees of lean; however, the 0.5 Gs of lateral force corresponds to 26.6 degrees. The instrument also contains an accelerometer, which is able to measure the total acceleration that acts on the horizontal plane. The total acceleration can be split in longitudinal and centripetal acceleration values. The centripetal acceleration is what the lean of the bike compensates. However, the angle of lean is not directly proportional to that acceleration and its reaction: the friction force or grip of the tires. The proportion goes like this: 10 degrees: 0.18 g 20 degrees: 0.36 g 30 degrees: 0.58 g 40 degrees: 0.84 g 50 degrees: 1.19 g

No "pushing the bike underneath you" here: http://www.youtube.c...feature=related

Could you explain this a little further?

You are welcome

The new diagram is exaggerated regarding angles and locations of centers of gravity, but shows the basic principle.

Not true I'm afraid. The amount of centripetal (cornering) force produced, as Hotfoot says, depends on the amount of weight and how far inwards (horizontally) it is of the contact patch. This varies with lean angle of course, and a tall bike will thus produce more of it than a short one at the same lean angle. If you watch the attached diagram with your head tilted to the right, you will see a bike rolling on one side of the tires, over an inclined road, and carrying a weight somehow higher than its natural weight (bike+rider). The leaned bike is balanced because all the forces go to ground through the tires, just like when it is traveling in a straight up position. When properly leaned in a turn, a motorcycle is as stable as when perfectly straight. The reason being that the weight of the bike plus the forces generated by the circular movement don't point vertically down but towards an angle between vertical and horizontal. Hence; the height at which the CG is located has no influence on the total (bike+rider) lean angle.

Thank you both very much.