Keith Code’s No BS bike
 by
David L. Hough
Keith Code, a veteran motorcycle road racer, instructor,
and author, believes firmly that countersteering is the primary input to cause
two-wheelers to turn. Keith and a cadre of instructors teach his Cornering
School at various tracks around the USA, England, and Australia. After reading
my March 2001 article on Countersteering in Motorcycle Consumer News, Keith
contacted us to bring our attention to his “No BS” bike (No Body Steering). As a
proponent of countersteering, Keith finally got tired of hearing about “body
steering” from his students who had attended other track schools, and built an
experimental motorcycle to allow riders to prove to themselves whether body
steering or countersteering was the dominant cornering input. Keith asked if we
would like to try the No BS bike ourselves. We accepted.
To set the stage for riding the No BS bike, let’s consider
a quote from another famous two-wheeled authority:
“I have asked dozens of riders how they turn a bike
to the left. I have never found a single person who stated all the facts
correctly when first asked. They almost invariably said that, to turn to the
left, they turned the handlebar to the left and as a result made a turn to the
left. But on further questioning them, some would agree that they first turned
the handlebar a little to the right, and then as the machine became inclined to
the left, they turned the handlebar to the left and made a circle, inclining
inwardly.
To a scientific student it is very clear that
without the preliminary movement of the handlebar to the right, a movement of
the handlebar to the left would cause the bike to run out from under the man…yet
I have found many people who would deny having ever noticed the preliminary
movement of the handlebar. I have never found a non-scientific rider who had
particularly noticed it and spoke of it from his own conscious observation and
initiative…”
The source of our example may surprise you: Wilbur Wright,
just about one hundred years ago. You remember Wilbur, the bicycle mechanic who
built the world’s first airplane. OK, I fudged the words slightly. Wilber said
“bicycle” not “bike”. But two-wheelers balance and steer the same, whether
powered by pedals or an engine. For the past 30 or 40 years we’ve been calling
this “countersteering”.
One of the most concise technical papers I have found on
the subject is “Anatomy of a turn” by Hugh H. Hurt, first presented at the
Second International Congress on Automotive Safety, July 1973. Yes, we’re
talking about the same “Harry” Hurt who was the principal investigator on the
landmark “Hurt Report”.
Hurt points out in his paper that the initial steering
input to cause the motorcycle to begin to turn causes the front tire contact
patch to out-track, and that once the motorcycle is leaned into the turn, a
second steering input is required to cause the front wheel to “in-track”.
(Figure 1)
We bring up these experts to set the stage for a serious
question: Is countersteering a result of the rider actually turning the
handlebars, or can the rider initiate countersteering just by moving body weight
around in the saddle? Most of us can remember some situation in which a
passenger wiggled around on the back of the saddle and caused the bike to change
direction. But is the primary steering input through the handlebar grips, or
through some other part of the bike, say foot pressure on the pegs, knee
pressure against the tank, or body weight shifted in the saddle?
Now, by body steering we’re not talking about hanging off
the bike to increase leanover clearance, or shifting weight in the saddle to
counteract a steady crosswind, or standing on the pegs of a dual sport to get
more weight on the front tire. We’re talking countersteering to cause a street
bike to lean into a corner, or straighten up again.
Before we go on, let’s define “steer”. Code admits that a
rider can balance a bike in a straight line, hands-off-the-grips. To Keith,
that’s not “steering”, just balancing. “Steering” to Keith would be to take the
bike through a corner, say a nice S-curve.
The MCN editors didn’t have any dreams about making
S-turns, but we figured we could at least balance it in a straight line without
countersteering. To help answer the question, we made a fast trip to Willow
Springs Raceway where Code was conducting a two-day Cornering School, and had
the No BS bike available.
The No BS bike is a 600cc Kawasaki sportbike with one
simple modification: a second handlebar is attached rigidly to the frame just
forward and above the normal handlebar attached to the front end.
 The
No BS bike has one simple modification: a second handlebar attached rigidly to
the frame.
The second handlebar has a parallel throttle, so that the
rider can maintain speed. There is no parallel clutch control on the left side,
and no front brake, for reasons which become obvious when you try to ride the
bike.
 NBSB
hbars 01: The fixed bars have a throttle, but no clutch or brake.
The machine, and the concept, is brilliantly simple. If
you believe that you can steer a motorcycle by how you shift your weight around
on the bike, then you should be able to hold onto the fixed handlebars, and
steer the NBS bike normally.
My first optimistic attempt to ride the No BS bike was on
a narrow slip road adjacent to the track. The training range was busy, so I took
the bike over to this straight road to be away from school traffic—and away from
prying eyes in case of embarrassment. There wasn’t a lot of room for error,
since there were fences on both sides. The road also had a slight crown at the
center, and there was a gusting desert crosswind adding some challenge to the
situation.
The drill is, get the bike rolling and up to 30 or 40 mph
in second gear, with the normal controls.
 First,
you get the NBS bike rolling and up to 30 or 40 mph in second gear, with the
normal controls.
When you’re ready to try body steering, move your right
hand to the throttle on the fixed handlebar to maintain speed.
 Next,
move your right hand to the throttle on the fixed handlebar to maintain speed.
At this point, your left hand is still controlling balance
with the left grip.
At
this point, your left hand is still controlling balance.
Then, get your nerve up, and move your left hand to the
fixed bar.
 When
you’re ready to try pure body steering, move your left hand up to the fixed
grip.
Now, both hands are on the fixed handlebar, and you’re
attempting to control direction by body steering.
 Now,
you’re holding onto the fixed bars only.
On my first run, a gust of wind immediately blew the bike
to the right, and I quickly returned my left hand to the normal grip to keep out
of the fence. My feeling on the fixed bars was panic. I turned the bike around
and tried a downwind run. Within two or three seconds, the bike headed off
towards the right. Both MCN Senior Editor Fred Rau and I tried to ride the No BS
bike on the narrow road, with similar heart-thumping results. We immediately
appreciated the sly comment Keith had tossed us over his shoulder as he walked
away. “If you figure out how to body steer, be sure and tell me.”
Later, after the students had all gone out to the track, I
commandeered the wide-open training range where the bike could theoretically
head off on its own without running down fences, and I attempted a few more
runs. I tried upwind and downwind, but the best I could manage was three or four
seconds before the bike began to peel off, and I would grab for that left grip
to regain control. The feeling was that the bike was about to circle into a
death spiral and crash, and there wasn’t anything I could do about it other than
grab for the left grip to regain steering control. It only took me about four
seconds to conclude that body steering didn’t do much. It becomes very clear
very quickly that if you can’t countersteer the front wheel, you can’t control
the bike.
Keith Code isn’t the first motorcycle enthusiast to ask
serious questions about countersteering vs. body steering. Back in the 1960’s,
current MCN Technical Editor Tony Foale had just taken up motorcycling, and
heard about some studies by Wilson-Jones, then the chief engineer at Royal
Enfield. Tony became curious about motorcycle geometry, and went looking for his
own answers.
Foale was a student in Electrical Engineering, at a
university in England, and had access to some instrumentation. He could
occasionally slip away with some instruments and a massive tape recorder
strapped to the back of his bike, then analyze the data back in the lab when the
boss wasn’t looking. Tony did a number of experiments, including a “fake”
handlebar that turned but wasn’t connected to the front end, and a rigid frame
he could strap himself to, to eliminate body movement. He also did many
experiments with wide variations in rake and trail.
No photos exist of any of Foale’s test bikes, and for good
reason. Remember, he was doing his experiments on the sly with equipment
“borrowed” from the university. It wouldn’t have been smart to have photos of
his projects floating around, even if Tony had thought to document what he was
doing.
Considering the importance of engineering to motorcycling,
you would think that factories do considerable research on motorcycle dynamics.
But apparently not much research has been done, and most of that has been
accomplished outside of the factories. As Foale puts it, “It never dawned on me
that I was actually doing something way ahead of my time. I just assumed that
real life motorcycle designers knew all this stuff but weren’t about to tell a
brash teenager, so I had to do it myself.”
Foale is currently working on a huge book on motorcycle
dynamics. To satisfy the demand for information, he has a CD-ROM preliminary
version available, for US$40, which applies to the eventual cost of the printed
book when it is released.
Today, if you do a computer search for motorcycle
references, with key words such as “suspension”, “kinematics”, “lateral
dynamics”, “stability” and “vibrational modes”, you can find something like 150
different papers, worldwide. The trouble is, for those of us who aren’t trained
scientists, most of it will be unintelligible techno-wackie.
That’s what’s so great about Keith Code’s No BS bike. It
cuts right through all the engineering theory, and gets to the heart of the
matter. If you get a chance to ride it, do so. Forget all the chit chat, strap
your helmet on tight and let your theories bump up against reality.
Everyone who has tried the No BS bike has come to the same
conclusion: all that elbow-waving, knee-slamming, shoulder-leaning body English
may be good for your heart and muscles, but it doesn’t do much to control the
bike. Two wheeled motorcycles are balanced and steered by countersteering the
front wheel, just like Wilbur Wright said.
Dave's Resources:
Technical paper, Second International Congress
on Automotive Safety, Motorcycle and Recreational Vehicle Safety, Paper no.
73032, “Motorcycle Handling and Collision Avoidance: Anatomy of a Turn by Hugh
H. Hurt Jr. University of Southern California, July 1973
Motorcycle Handling and Chassis Design (the
art and science) preliminary CD-ROM version US$40 Information:
www.tonyfoale.com,
tfoale@email.com or fax +34 96 6404389.
|
