作者: tempest (變態小松鼠) 看板: SafetyRiding
標題: 【文件】The NO BS Machine by K.C
時間: 東吳機研站 Tue Jul 23 01:27:38 2002
分享一篇文章, 不曉得是否適合放在這裡
不過我覺得蠻有趣的 和前面的文章有一點點相關性
原文是K.C先生post在newsgroup上的
文章出處http://www.motorbikeracing.com/code.htm
此處轉載並未獲得原作者及原轉載者授權
(印象中在K.C開的CA賽車學校網站上也有這篇文章, 還有照片, 一時懶得去找了)
------------------------------------------------------------------------------
Keith Code has a remarkable knack of explaining sometimes the
unexplainable. He has a number of books in print defining the science
of motorcycle riding. OK, so he's not a world champion, but the boy
sure can teach. Here Keith built a ZX6R with a second set of rigid
handlebars to demonstrate the bodies involvement in the process of
turning your motorcycle. Read on...
The No BS (Body Steering) Machine...
The Correct Brothers
It shouldn't be alarming to me that riders still
question how to steer their motorcycles but it is. Apparently, even
after 90 years when it was first observed by the Wright brothers some
confusion remains on this subject . Yes, their first engineering
attempts were as bicycle manufacturers; the very observant brothers
determined that tandem (one wheel in front of the other) wheeled
vehicles counter steer. That was and still is correct.
Sources Of Confusion
It is easy to see how confusion arises on the
subject of steering for anyone of us who started their riding on
pedal bikes. The steering is so light on a bicycle that riders have
difficulty in separating the shift of their body mass (leaning into
it) with the slight effort it takes to countersteer.
Further confusion arises from word of mouth advice on riding. I have
even seen articles in usually credible national magazines extolling
the virtues of body mass type steering. Body Steering as it is
called. I have surveyed thousands of riders on this point. Most
riders still believe that some of the steering is being done with
their body mass or weight shift or pressure on the motorcycle's tank
or pegs. Their estimates on how effective these are in getting the
bike to turn range anywhere from 10% to 90%, some believe all of it
is weight shift.
Swoopy Steering
If it weren't so grim, it's almost comical to watch a
rider who does not understand how steering is accomplished. You can
see them riding down the freeway trying and failing to change lanes
by body steering and still appear cool while doing so. I have seen it
dozens of times. It goes like this. The rider does a very swoopy
upper body swing in the direction he wishes to go but for an
agonizing moment (to me) nothing happens. There is a perceivable lag
between the upper body swoop and the bike's deflection from its
original course. How terrifying it must be to find that the bike
doesn't instantly respond.
Stiffen To Steer
Following that is a stiffening of the rider's upper
body. Only then does the bike respond and change lanes. You see how
this works? The rider's body is positioned off-center, from his
swoop, in the intended direction of the lane change. The stiffening
on the bars creates the countersteering action, because he has either
pushed on the inside bar or stiffened and pulled on the outside one
or a combination of both. This stiffening is actually a mild panic
reaction. Many riders have simply learned to live with the lag and to
think it is how their bike handles. That is false, a motorcycle
responds almost instantly to countersteering.
Vague Technique
Riders have a number of ideas, which are vague and
hard for them to describe, on just how their weight shifting
accomplish this so called body-steering. "Throwing" their upper body
mass to one side or the other (the swoop) is one. Some say they just
push down on the inside peg. Some say they pull the bike over with
the outside leg against the tank. Some say it is a combination of two
or even all three of the above methods. Do they work?
I'll leave it up to the tech boys to figure out the WHY of motorcycle
counter- steering. Their job should be to provide a simple
demonstration of how it works. The fact is that countersteering is
still being argued in the halls of learning with slide rules, Physics
formulas and calculators. Many theories exist but no conclusive
statement that I know of as to why has yet been reached. Argue on
boys.
Clear The Issue
My job is to make riding simple and clear up
conflicting information that a rider may have on the subject of
riding. Any confusion translates into reduced control, as in the lag
from swoop to lane change, and confidence, as in the bike won't do
what I want it to, when I want it to. Riders don't like the
uncertainty and love confidence.
I decided to make this steering issue, body vs counter, very simple
and very plain. I reasoned that anyone who could see how it works and
experience the real steering procedure would have dramatically
improved their chances of survival against the perils of 21st Century
Earth street riding. Steering must be done and done quickly if a
rider has any hope of confidently neutralizing those perils.
Expert Opinions
I was actually in a deep confusion on this subject of
body-steering myself. Riders the caliber of Eric Bostrom have told me
that they do it to some degree to help steer. Freddie Spencer has
made a statement to that effect and of course Reg Pridmore has made
it the banner for his CLASS schools for 15 years. Jason's STAR school
has been written up as teaching body steering as well.
With great to good credentials like that it should be so, and even I
was a little shaken in my certainty. Maybe there was something in it
after all. I hate to miss anything.
The Experiments
For my part, experimenting with pressure on the pegs,
the tank, adjusting my body mass and combinations of all three on the
bike resulted in nothing I would consider steering. In other words,
something that could be used in an emergency maneuver or to
aggressively flick the bike into a corner or through a set of esses.
Eventually I arrived at a potential solution to my questions that
would eliminate my opinions and/or misunderstanding on the subject.
The Solution
Make a bike that has two sets of bars. One set as
normal, the other set would be solid mounted to the frame so they
were not connected to and did not rotate the forks. This, as my
theory went, would answer the question. And it does.
The Machine
Taking one of our Kawasaki ZX 6Rs and solid mounting a
set of bars 8" above the standard ones would positively isolate the
various body shifting from the countersteering. If body-steering had
any effect it would be simple to show it. I created a bike with that
setup.
One necessary detail was to mount an additional throttle on the
upper, solid mounted, bars so the bike's stability could be
maintained as the user rode down the road. So we wound up with two
sets of handlebars and two operating throttles on the bike.
MachineDirty Exceptions
Before I go any further, I want to address off-road motorcycles. An
off-road motorcycle will easily steer by pressing down on the inside
peg, and in conjunction with shifting the upper body mass, will go
over pretty easily . Still not what I would call good control but it
can be done fairly efficiently.
Again, I am not a true tech guy but it occurs to me that the small
contact patch on knobbies or dual sport tires and dirt bike steering
geometry, which is not intended to provide an enormous amount of
stability at speed, contribute to the reasons why steering results
from weight shifts to the degree it does on a dirt bike.
No Body Steering.
At this writing, we have run nearly 100 riders of
all experience levels on this double barred bike. It has made
believers out of every single one in the actuality of countersteering
of course.
At 20 to 35 mph, no matter how much you tug or push or pull or jump
around on the bike, the best we saw was that the bike wiggled and
became somewhat unstable. Did it turn? Not really. Would it turn at
higher speed? Absolutely not.
The best result was one of my instructors. He got into a full hangoff
position and was able to persuade the bike, by jerking on it, to
start on a wide, wide arc in the paddock at Laguna Seca, a piece of
asphalt that is about 500 X 800 feet. Like turning an oil tanker
ship, start at noon and be on the turning arc at around 1:00 PM. It
wasn't very smooth and it wasn't very effective.
We now call this bike "The NO BS Bike". There are no doubts in
anyone's mind after they ride it that they have been countersteering
all along. No doubts.
You can hear riders, who believed in the body-steering method,
laughing in their helmets at 100 yards away once they get those solid
mounted bars in their hands and try to body-steer the bike. They just
shake their heads. No BS.
Dangerous Misconceptions
Now if you want to look a little further
into this, what you will see is this; riders who still labor under
the misconception that they body-steer are devoting themselves in a
system that can do a great deal of actual harm.
Firstly, it is seriously misguided to add an additional series of
actions to the steering process. When it is quick, critical steering
that is needed to avoid something, that lag I have observed so many
times in street riders, could cost you your hide.
Adding 2/10ths to 5/10ths of a second to the steering procedure at 60
mph means that you have just gone another 18 to 44 feet down the road
before you started to avoid that muffler lying in your path. Kids,
don't try this at home.
The way things are going there will be warning labels on motorcycles
in the not too distant future...
WARNING: THIS VEHICLE COUNTER-STEERS. IF YOU DO NOT UNDERSTAND
COUNTERSTEERING DO NOT RIDE. SEEK THE HELP OF A QUALIFIED
PROFESSIONAL INSTRUCTOR!
Bull Steering
Another recognizable error, resulting in excess effort
used to steer the motorcycle, is the attempt to turn the bike by
bulldogging the bars. An interesting combination of pulling up on one
and pushing down on the other rodeo style, like bull wrestling. No,
repeat No, steering results from this. None, zero, nadda, niente.
Riders who think they can twist the bike into a turn in this fashion
simply have another false idea and get tired.
The Bottom Line
Steering a motorcycle results from the process of
pushing the inside bar forward, the same angle and direction the
forks rotate in the steering head bearings. You can also pull on the
outside bar. You can do both push and pull. That is what turns it,
that is all that turns it with any degree of accuracy, efficiency,
quickness or smoothness.
That and only that, No BS.
Keith Code
Keith Code can be found teaching at the Californian Superbike School
in between wacky science projects. See more at www.superbikeschool.com
--
※From: 東吳機研 scumotor.com.tw tempest From 61.231.27.78 ...
一個玩車人的天地/各車系專屬區/GP SBK TIS賽事討論區/進口車討論區/