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Feedback: Bicycle Stability/Counter-Steering and thanks to Phil Parker of Wichita



Hi Physics Phriends,

Leigh Palmer wrote:

I'll suggest a Gedankenexperiment (Please don't try it!). Ride a bike no
hands at moderate speed on a parking lot with your eyes shut. I find that
I am absolutely dependent on visual feedback to maintain my upright
condition.

TRY THIS: To quickly learn the importance of visual feedback, stand on
your tip-toes (barefoot is better) with your eyes open and then with your
eyes closed. Eyes open is much easier.

OPTIONAL ASIDE: I took up downhill skiing just two years ago (at age 54)
and I love it. My doctor (a sports medicine expert) suggested doing about
20 tip toe stands daily not only as a strengthening exercise (eyes
open/closed - doesn't matter) but, with eyes closed, to improve my
balance/equilibrium. With no research data whatsoever, I think it really
helps.

BACK TO FEEDBACK: I've taught the Riding and Street Skills course for the
Motorcycle Safety Foundation and have regularly run into experienced (?)
riders who were self-taught and had never heard of counter-steering.
Often, they couldn't tell me what they did to make the motorcycle lean
until they rode the bike AFTER talking to me and consciously paid attention
to what they were doing. Only then did they discover that to lean the
motorcycle, they were gently pushing on one handlebar and gently pulling on
they other. How did they learn that without being taught? By immediate
feedback when they were first learning to ride the motorcycle. They
subconsciously ended up doing what worked. The only problem with learning
to ride that way: Let me quote from an article in the March 1989 issue of
Rider Magazine: ".... Of course, pressure on the outside handlebar
straightens the bike, and accident investigators routinely uncover evidence
of panic-stricken riders pushing on the wrong side in an attempt to
"car-steer" the wheel away from the approaching hazard."

Thank you, Thank you, Thank you !!

I started this thread on Motorcycle Counter-Steering which became Bicycle
Stability last December and I have enjoyed immensely the discussions which
have ensued. I have learned so much all who have contributed. That's what
makes this list so great. I haven't met any of you in person and yet I
feel comfortable calling you my Physics Phriends. I want to publicly thank
Phil Parker for his private help in getting the Einstein Domino Mapping
posted as a *uuencoded GIF file* and he is continuing to help one of my
students with the problem of posting my Mac Voyager Hale-Bopp files on his
IBM based homepage.

MORE TO COME

I currently have a student making diagrams which will (try to) show that
counter-steering a motorcycle causes it to precess just as the weight of a
toy or bicycle gyroscope causes it to precess. When finished (?? he's very
busy), I will post it as a uuencoded GIF file.

ME ? I'm too busy downhill skiing almost every weekend to do it all
myself. Anyway, let them go through the learning curve, and then they can
teach me.

Bye, DiRT



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David R. Thiessen FUN + PHYSICS = PHUN
Science Department PHYSICS IS PHUN !!
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dthiessn@nslsilus.org (Quote sources long forgotten)
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