Lnewqban
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Posts posted by Lnewqban
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Looking back at the original question of "Can quickturn be overdone"
The answer is of course yes, all tires have a limit of traction and that can always be exceeded, however that limit might not be low enough that you personally, or any human for that matter, can physically overcome.
...........Thanks, Tyler!
Here is a new article from Keith on successive quick turns:
http://www.motorcyclistonline.com/features/columns/transitions_code_break/
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.........On the other hand, what's the point of turning faster and faster?
From "A twist of the wrist II" / Chapter 12:
"You can determine any rider's basic skill level by how well he can change directions, steer his bike, flick it in, lean it, get it turned, bend it in, bend it over, crank it over, tilt it over, stuff it in, snap it in - call it what you will, there is a scale of rider ability and nowhere is it more obvious than in this action of riding." - Keith Code
This is the way I understand the technique:
Leaning in and out quickly makes a clean straight-curve-straight transition, keeping the max possible radius of turn (and the minimum lean angle through the turn).
Just like in a "U".
Doing it slowly, you enter and leave with a huge decreasing and increasing radius, just to need a smaller than necessary radius (bigger than necessary lean angle) by the middle of the turn for compensating.
Just like in a "V".
Entering a left turn (right to left in the schematic) using a lazy lean over, you can see that the radius is slowly getting smaller as the lean angle increases, just like in a decreasing radius turn.
In essence, by doing that your line is stretched respect to a more ideal and efficient line.
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..........the basic answer to Lnewqban's question is that you transition the body before you steer the bike in a chicane, if possible, and you should have the lower body locked-in so as to get the most powerful and accurate steering input you can.
Thank you very much, Hotfoot
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4) How to use it in a chicane... let's see, I guess it would go like this: turn the bike quickly, then shortly after that turn it quickly the other direction.
I'm not quite sure what you are asking about how to use it in a chicane, can you be more specific? Certainly quick turn is extremely useful in a chicane, where a fast transition is critical.
Yes, my question about the use of quick turn in a chicane is related to the sucesion of timing of body position changes and steering inputs.
Thank you!
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Reading this article from Keith Code, I wondered what is the physical limit for this technique?
http://forums.superbikeschool.com/index.php?showtopic=109
I would also like learning any subtle tips from the couches.
For example:
1) It is done while still braking or completely off the brakes?
2) More force or more speed while steering, or both?
3) Body position and sight direction before, during and after?
4) How to use it in a chicane?
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Wind drag is the biggest factor at top speed on those bikes, and they are narrow, so every little bit of tucking in helps.
Doesn't knee dragging produce the same wind drag effect?
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The hanging-off effect of a tall heavy rider is more: that rider can keep the suspension a little more functional (can lean the bike a little less) than a short light rider for similar bikes.
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Please, explain this fragment:
"Then work on cornering grip, not drive grip."
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...............This is just a long-winded way of saying that you should not try to reason that cornering Gs on a bike would be no better than driving or stopping Gs. The G-limits of cornering are different from those of driving and stopping.
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-Eric
Eric is very correct.
Around two years ago, I took some time to run some calculations and to draw an AutoCAD schematic overlaying a picture of Stoner:
http://forums.superbikeschool.com/index.php?showtopic=3324&&page=3#entry26802
At that instant, he and his bike were leaning 57 degrees respect to a vertical line and he was feeling 184% heavier in that angle's direction (1.84 G).
The contact patches were feeling a lateral force 154% higher than the weight they felt vertically (1.54 G).
It seems to me that one of the limits in that case was the lateral clearance (leg against track).
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Besides whats thaught in the book/video, how do you guys practice the gear shifting on a motorcycle?
Just by doing it as you go.
It is a very intuitive thing to learn.
The principle: as you increase or decrease the speed of the motorcycle, the engine rotational speed cannot cover the wider range of rotational speed of the wheels, so you select the correct combination step by step.
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2) Learn to pass in the corners and in the parts of the track where big bikes have to slow down more than you.
Why big bikes have to slow down in the corners and in other parts of the track?
More mass typically means lower corner speed; the forces required to hold a heavier bike in a turn are higher: F=mA. (Lighter bike = faster through corners is a generalization, of course - a lightweight bike with terrible tires or lousy suspension would not necessarily get around a corner faster than a 600 with super grippy tires and great handling).
Areas of the track that have tight transitions (corners 4-5-6 at Streets of Willow, for example) favor lightweight bikes because you can flick them side to side more easily and faster, and thus carry more speed through the whole section.
Thanks, Hotfoot!
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2) Learn to pass in the corners and in the parts of the track where big bikes have to slow down more than you.
Why big bikes have to slow down in the corners and in other parts of the track?
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....................Super light touch (after the steering is done). Easy to say, but...
If I understand it correctly, a lot of force on the bars for quick steering is followed by a super light touch.
However, quick steering and the associated steering force must be dialed down some when riding on wet surfaces, IMHO.
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Hi guys I hope this is a big subject for a few of you in the wetter regions of our lovely planet.
I ride all year on less than grippy roads in England and just wondered if any experts out there have got some tips for carrying a bit more speed in corners in the wet.....
I also live in a humid environment; we either street-ride in storms or we seldom ride.
Although not directed to push the limits (never a wise approach to street riding), here are some tips from an expert, David L. Hough, author of "Proficient Motorcycling" (highly recommended book):
http://www.soundrider.com/current/1310/6Secrets-RainRiding.aspx
Regarding available traction, I could add that there is a huge difference between the effects of a light rain on dirty pavement and of a heavy storm that washes grime away.
Rather than assuming and over-estimating lack of traction, you can safely test how much is available for a particular condition by front-braking on a straight line.
If you have been practicing emergency braking, you could compare how much less skidding/sliding load the front patch can take on a wet surface.
For a rough approximation, you can assume that a lean of 45 degrees demands about the same lateral load than lifting the rear tire during braking (about 1 G), while average emergency braking (about 0.85 G) is equivalent to 40 degrees of leaning in a turn.
Note however, that the angle of lean is not directly proportional to lateral 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
60 degrees: 1.73 G
At 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 ATOTW2
Consider tire's temperature as well: when raining, you can safely deflate the tires some (80~90%), so they reach proper temperature despite the cooling effect of the splashing water (but don't forget to increase pressure for dry riding).
This video shows what is possible on clean wet asphalt with street tires (only ones legal in Motogymkhana).
............And yes, practice and competition of Motogymkhana is in full swing in UK:
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Assuming a 180 degree constant radius corner, when are you at your maximum lean angle?
1) When you are trailing off the brakes
2) Split second of no throttle
3) Maintenance throttle
If you are following the trajectory of that 180 degree constant radius corner, you are at your maximum lean angle when you reach the maximum speed; hence, at the end of your maintenance throttle (#3 above).
Note that with proper maintenance throttle (40/60 weight distribution), you are gaining around 3 mph per each second that you are turning.
However, if you are not following a perfectly circular trajectory, as in the cases explained above, you are at your maximum lean angle at the instant when you reach the combination of minimum radius of turn and maximum speed.
For any practical purpose, instantaneous lean angle solely depends on the square of the instantaneous velocity of the bike and on the inverse of the instantaneous radius of the circular trajectory.
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................ In otherwords I was having a Forest Gump moment "Stupid is as Stupid does"
No stupid at all, these things are difficult to see.
Cornering properly at the track means successfully dealing with the centripetal acceleration and its associated forces that try keeping us going straight instead of making a curve.
As we all know, those cornering forces depend on the square of the velocity and on the inverse of the radius.
The radii of turns in the track are huge, which make us focus on velocity (any number elevated to square can grow or shrink fast); hence, the required fine senses of entry speed and throttle control.
In those conditions, when we need a rolling lateral force to change lean angle, we momentarily change the centripetal acceleration by changing the radius of the turn via counter-steering.
The radii of turns in the Gymkhana track are so small that become the main factor in the formula of centripetal force (any number divided by almost zero becomes almost infinite); hence, a little change in velocity gives enough rolling lateral force to come out of lean.
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Lnewqban it is interesting that you mention rear tire speed, would you care to elaborate on that statement?
I will disagree with the countersteering statement about minimum to non-exiting though and go back to my earlier question: At what speed would you not have to countersteer?
Hope this helps you, but ............... you have brought your question to super-fast track riders who seldom ponder the mysteries of slow riding.
Are there any differences between the two? If so, what are they?
Bonus question: What is the same between super fast track riders and Gymkhana riders?
Yes, the extreme rotational maneuvers make the rear tire move much slower than the front tire.
Actually, the rider tries to complete the maneuver with the minimum possible trajectory of the rear tire, because trajectory has more influence on shortest attack times than speed.
It is not that there is a speed below which you wouldn’t have to counter-steer; the problem is that the rider cannot turn the handlebar anymore: the circle is completed at full lock due to the reason explained above.
Are there any differences between the two? – Yes:
- The magnitude of the angle of steering.
- Steering the bike at full lock by acceleration rather than by counter-steering.
- For one rider, speed is key; for the other, it is radius.
- One rider avoids max lean angle; the other induces max lean when at full lock (because that reduces the radius of turn).
What is the same between super fast track riders and Gymkhana riders? – Fine sense of balance.
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So how is the dirt of a flat track any different than any reduced traction surface? You don't see riders sliding like that in rain so why does that technique work on dirt and not asphalt?
Riding in the rain offers much more traction for steering than riding on dirt.
As that front tire has almost zero steering capability while the bike is moving forward on dirt (if you steer or counter-steer, the bike keeps moving forward), the only way to cornering is pushing it sideways with the rotation of the rear tire.
As the rear tire spins and skids, it develops some traction, which pushes the whole bike sideways and forward simultaneously.
By doing that, the front tire acquires some marginal steering capability (get greedy about steering and the bike quit steering and resumes forward movement).
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I was watching this Moto Gymkhana video and am trying to work this out -
They counter steer to weave in between the cones.But when they do U turns and circles, they are turning the bars right to go right and left to go left...?
Are they initiating the U turns and circles by countersteering and then turning the bars right to go right and left to go left...?
Help me understand this? Thanks
What you see is less evident for track or street riding: big changes of speed between maneuvers (from and to almost zero mph for the rear tire).
That makes countersteering minimum or non-existing.
Going into lean to go around the obstacle, yes, countersteering to initiate the rolling movement and then strong braking-steering that finishes the lean needed to keep balance around the cone.
Going out of lean leaving the obstacle, no, zero countersteering (as the steering has been locked against the end while rotating around the cone) to straighten the bike, just strong acceleration and steering.
Hope this helps you, but ............... you have brought your question to super-fast track riders who seldom ponder the mysteries of slow riding.
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I found this idea really interesting. Has anyone else experienced this or thought about it?
You made me go to the dictionary for Proprioception, ........ what a word!
My experience has been the opposite: riding at night fools me regarding actual speed.
The tunnel vision and being able to mainly see things that are close to my eyes and seem to move faster, make me estimate my speed as higher than it really is, at least 5 mph above.
I don't believe that my proprioception, regarding sense of balance, improves at all due to darkness.
There is no way to be more perfectly balanced than during cornering: you are either doing it in balance or doing it dangerously wrong.
In summary, night street riding, besides being dangerous, messes up my evaluation of entry speed.
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P.S. Tried searching and only found this topic.
Here you are:
http://forums.superbikeschool.com/index.php?showtopic=2115
http://forums.superbikeschool.com/index.php?showtopic=2522
http://forums.superbikeschool.com/index.php?showtopic=3507
http://forums.superbikeschool.com/index.php?showtopic=3594
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In Twist II Keith describes four different types of information you could receive about riding.
I'm curious about what sorts of things YOU have been told about riding (outside of the school), on the road or track, on the internet, from riding buddies, or motorcycle salesmen, etc. - whether it is funny, scary, misguided, true but not helpful, or just downright bizarre...
Challenge 1: name the four categories of information from Twist II.
Challenge 2: share with us what you have been told, and which of Keith's four categories you think best describes it.
Here are some things I have been told over the years:
"You just need to get more aggressive with your riding."
"Don't worry about adjusting the suspension, that really doesn't make any difference." (this was from a motorcycle dealer, BTW)
"Trust your tires."
What category(s) do these statements fit in, and what other examples can you share?
Challenge 1: Destructive advice, friedly advice, useful tips and real technology.
Challenge 2: Early in my riding life I was told "In slippery conditions, use engine brake rather than rear brake". I have tested this useful tip during many years and can testify that it has worked as a champ for me. The reason behind is that the braking effect of the engine is pneumatic and more self-adjusting than the one coming from the foot-rear caliper.
"You just need to get more aggressive with your riding" and "Trust your tires" seem to be friendly advices.
"Don't worry about adjusting the suspension, that really doesn't make any difference" seem to be destructive advice.
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It seems crazy that you were able to cover almost 180 degrees of curve, just to run wide at the end.
Going up hill, we need less acceleration to keep the proper weight balance, as the rear feels more weight than the front.
Too much throttle in those conditions and you could overload the rear and harden the steering.
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.........I see lots of riders who come in to fast and hard on the brakes, make about 37 steering inputs to get through the corner and gas it hard on exit, or just come in so hot I'm amazed when they make it through the corner without crashing. Then I see for example, Cobie who looks almost lazy and slow as he glides through the corner and easily breezes past the other rider.....
Then, was Cobie who inspired Keith to write this:
"Less-skilled riders sometimes seem bent on doing something all the time, and they appear busy because of that. Seasoned riders better understand when to do something and when to do nothing. Less experienced riders often look busy and nervous. Seasoned riders with evolved skills look almost lazy and relaxed, even when executing complex tasks. It’s like that in every sport or performance, not just on a motorcycle.
........A rider that knows how to make the right decisions proactively doesn’t appear tense and stiff, like a rider who is anxiously waiting for something to happen and then trying to react.
........Every rider has the goal to be smoother, faster, more confident, and to feel less at-risk while riding. Each of these goals is achieved by making the optimum micro choices of action or non-action. To do or not to do, that is the question.
........Understanding is the foundation of improvement, and understanding is the most direct route to the level of skill you envision for yourself and your riding."
Please, find the full article here:
http://www.motorcycl...lls_code_break/
.................I think part of being a "good" rider is having certainty you are in control of the bike; knowing where it will go, and why, and how to make it do what you want it to do, instead of just holding on and hoping it works out.
Fully agree!
Then, good riders excel from the rest by deciding proactively and understanding what and when to do something or not and by executing that task in a relaxed and calmed manner, regardless the complexity of the task or the type of riding or bike.
Lean And Cornering G's
in Cornering and Techniques
Posted
In order to have a more realistic perspective, you could see that the dimensional changes and therefore things affected by hanging off are not dramatic:
http://forums.superbikeschool.com/index.php?showtopic=3324&page=3
Being motorcycling racing an extreme sport in which 0.01 seconds make a difference, a couple of degrees of less lean are worth the trouble of hanging off.
However, for street riding, with its safety margins, hanging off should be reserved only for unforeseen emergencies.
As lean angle increases, the divergence between the lines of suspension and bump forces increases as well.
There is also increasingly more weight applied along the line of the suspension, which moves both suspensions from their sweet spot settings.
As you explained, the elastic property of the forks and rear swingarm acts as a spring for side forces, and helps alleviate the bad situation some; however, there is no dampening effect and some undesirable oscillations follows each bump.
The more you lean, the higher is the force that translates into steering torque transferred from the bumps (vertical force) to the handlebar (which could induce tank slappers):
http://www.dinamoto.it/dinamoto/8_on-line_papers/Avancorsa/avancorsa_eng.htm