Bike stability physics

Peter Cole wrote:
On 7/7/2011 12:06 PM, Frank Krygowski wrote:

(...)

Americans, at least, certainly seem quick to think they know as much
as anyone on any subject at all. Witness things like confident
letters to the editor on topics like economics, international
diplomacy, climate change, etc., written by people who never quite
made it through secondary school.

I suppose that all cultures are plagued by hubris
at some point in their history.
http://en.wikipedia.org/wiki/Nazi_Germany

Some longer than others....
http://www.vatican.va/vatican_city_state/index.htm
http://en.wikipedia.org/wiki/Mafia

Though I do see your point.
http://en.wikipedia.org/wiki/Trail_of_Tears

And on subjects that appear easy, like riding a two-wheeler? Hell,
it's _obvious_ there's nothing to learn! If you can balance, you're
an absolute expert, and nobody can teach you anything!

I've wondered if this overconfidence is connected to America's "all
men created equal" concept. Are things different in countries where
class systems are more blatant? Anybody know?

America is as 'class stratified' as any other set of cultures.
Even the 'vast unwashed' try desperately to differentiate
themselves.
http://en.wikipedia.org/wiki/Hip_hop
http://en.wikipedia.org/wiki/Professional_sports

Jobst used to hypothesize that the biomechanics of counter-steering a
bicycle was similar enough to running that it was a "hard-wired" skill.
The learning curve is nearly instantaneous because we're just
cross-wiring into a skill we're born with. I think all cyclists
counter-steer, most without knowing it.

Depends on one's definition of the term, I suppose.

Using the 'counter-steering' technique (to advantage) is different from
the course-deviation that occurs when hitting the chord of
a divot in the road, for example. Both are fast direction changes
prompted by leveraging 'center of gravity'.
The former can get you around a corner quickly and safely.
The latter forces you (however temporarily or slightly) into a
direction you hadn't intended.

It's not lectures that help, but
practice. People just don't get much exposure to the need to swerve
suddenly, but it's quite natural, nothing counter-intuitive about it.

I don't understand.
'Steering left' to 'go right' is intuitive?
Can you clarify please?

It's just a matter of conditioning the reflexes. Mountain biking does
this pretty quickly.

I couldn't agree more (with this first sentence).


--Winston

On 7/8/2011 10:17 AM, Winston wrote:
Peter Cole wrote:
On 7/7/2011 12:06 PM, Frank Krygowski wrote:

(...)

Americans, at least, certainly seem quick to think they know as much
as anyone on any subject at all. Witness things like confident
letters to the editor on topics like economics, international
diplomacy, climate change, etc., written by people who never quite
made it through secondary school.

I suppose that all cultures are plagued by hubris
at some point in their history.
http://en.wikipedia.org/wiki/Nazi_Germany

Some longer than others....
http://www.vatican.va/vatican_city_state/index.htm
http://en.wikipedia.org/wiki/Mafia

Though I do see your point.
http://en.wikipedia.org/wiki/Trail_of_Tears

And on subjects that appear easy, like riding a two-wheeler? Hell,
it's _obvious_ there's nothing to learn! If you can balance, you're
an absolute expert, and nobody can teach you anything!

I've wondered if this overconfidence is connected to America's "all
men created equal" concept. Are things different in countries where
class systems are more blatant? Anybody know?

America is as 'class stratified' as any other set of cultures.
Even the 'vast unwashed' try desperately to differentiate
themselves.
http://en.wikipedia.org/wiki/Hip_hop
http://en.wikipedia.org/wiki/Professional_sports

Jobst used to hypothesize that the biomechanics of counter-steering a
bicycle was similar enough to running that it was a "hard-wired" skill.
The learning curve is nearly instantaneous because we're just
cross-wiring into a skill we're born with. I think all cyclists
counter-steer, most without knowing it.

Depends on one's definition of the term, I suppose.

I don't think there's much to dispute. Counter-steering merely initiates
a fall in the direction you wish to turn. You do that by putting the
tire contact patch to the other side of vertical. You then steer into
the fall, balancing the centripetal and gravitational forces. We do it
all the time, cycling or even walking.

Using the 'counter-steering' technique (to advantage) is different from
the course-deviation that occurs when hitting the chord of
a divot in the road, for example. Both are fast direction changes
prompted by leveraging 'center of gravity'.

I don't understand "chord of a divot" nor "leveraging 'center of gravity'".

The former can get you around a corner quickly and safely.
The latter forces you (however temporarily or slightly) into a
direction you hadn't intended.

The only thing that actually forces me in unintended directions are
grooves, like trolley tracks.


It's not lectures that help, but
practice. People just don't get much exposure to the need to swerve
suddenly, but it's quite natural, nothing counter-intuitive about it.

I don't understand.
'Steering left' to 'go right' is intuitive?
Can you clarify please?

Sure, being bipeds, we have the need to change the direction of our
momentum (esp when running) with a "contact patch" only at our feet. We
are always dynamically balancing, even when motionless, but when we are
running and need to turn sharply we need to perform exactly the same
maneuver as we do on a bike. It is likely we are born knowing how to do
it. You just have to transfer that innate knowledge to cycling, it's not
something that needs to be taught, just practiced. Most children get it
right away, otherwise they couldn't ride bikes.


It's just a matter of conditioning the reflexes. Mountain biking does
this pretty quickly.

I couldn't agree more (with this first sentence).

When it comes to bike handling skills, mountain biking typically
provides far more frequent situations to develop those skills. Since
it's a matter of reflexive, not book, learning -- a more challenging
environment speeds up the process and keeps the skills sharp. In
addition to turning and braking skills, it also improves a broad range
of balance, reaction time, spacial perception capacities -- especially
useful for older riders, as research seems to indicate a very strong
"use it or lose it" phenomenon, particularly with aging.

On Jul 8, 7:45*am, Peter Cole wrote:

Jobst used to hypothesize that the biomechanics of counter-steering a
bicycle was similar enough to running that it was a "hard-wired" skill.
The learning curve is nearly instantaneous because we're just
cross-wiring into a skill we're born with. I think all cyclists
counter-steer, most without knowing it. It's not lectures that help, but
practice.

I think having the background knowledge helps. In my mind, it's like
learning to play an instrument. We're all hard-wired to know how to
move our fingers; and lots of people get quite good on instruments
without lessons, just bumbling on their own, so to speak.

But a good teacher will give important tips, and will make the student
conscious of aspects of motion that the student might never realize on
his own. A specific example: "When lifting your finger free [of the
hole, the key, the fret, the string, whatever] try not to raise it so
high. That will allow you to increase your speed."

Such tips don't increase facility immediately. But as the student
thinks about them (perhaps subconsciously), internalizes them and
practices them, they do eventually help. I think the same is true of
certain on-bike moves.

In addition, coaches in any sport engage in the same sort of analyzing
and teaching, and get the athletes do a lot of educated practice. Few
question that it can be valuable.

- Frank Krygowski

On Jul 8, 11:12*am, Peter Cole wrote:

When it comes to bike handling skills, mountain biking typically
provides far more frequent situations to develop those skills.

So does delivering newspapers by bike in a huge suburban
neighborhood. At least, that was my experience.

- Frank Krygowski

On 7/8/2011 1:24 PM, Frank Krygowski wrote:
On Jul 8, 7:45 am, Peter wrote:

Jobst used to hypothesize that the biomechanics of counter-steering a
bicycle was similar enough to running that it was a "hard-wired" skill.
The learning curve is nearly instantaneous because we're just
cross-wiring into a skill we're born with. I think all cyclists
counter-steer, most without knowing it. It's not lectures that help, but
practice.

I think having the background knowledge helps. In my mind, it's like
learning to play an instrument. We're all hard-wired to know how to
move our fingers; and lots of people get quite good on instruments
without lessons, just bumbling on their own, so to speak.

But a good teacher will give important tips, and will make the student
conscious of aspects of motion that the student might never realize on
his own. A specific example: "When lifting your finger free [of the
hole, the key, the fret, the string, whatever] try not to raise it so
high. That will allow you to increase your speed."

Such tips don't increase facility immediately. But as the student
thinks about them (perhaps subconsciously), internalizes them and
practices them, they do eventually help. I think the same is true of
certain on-bike moves.

In addition, coaches in any sport engage in the same sort of analyzing
and teaching, and get the athletes do a lot of educated practice. Few
question that it can be valuable.

- Frank Krygowski

It's not that complicated. Children can do it.

On 7/8/2011 1:26 PM, Frank Krygowski wrote:
On Jul 8, 11:12 am, Peter wrote:

When it comes to bike handling skills, mountain biking typically
provides far more frequent situations to develop those skills.

So does delivering newspapers by bike in a huge suburban
neighborhood. At least, that was my experience.

- Frank Krygowski

Well for anyone needing the money I suggest a paper route instead of a
mountain bike -- to the extent that people read papers anymore.

On Jul 4, 4:00*pm, Frank Krygowski wrote:
Interesting article on the physics of bike stability:

http://www.newscientist.com/article/...-to-the-drawin...

orhttp://tinyurl.com/3szqyhk

Jim Papadopoulos was once a denizen of rec.bicycle.tech.

- Frank Krygowski

Thanks for that, Frank; most entertaining.

It's difficult to see how we are any forarder than we were in the late
1960s when a fellow called Jones used his wife's bike to prove, by
mounting the fork backwards, that trail was irrelevant to bike
stability. I'm not so sure, without looking it up, that Jones didn't
also prove that the other engineering shibboleth, the gyroscopic force
of spinning wheels, is also a deadweight of worn-out chains on bike
development. So, forty years later Ruina says that we have the
formulae, we just don't know what they mean. Maybe: he's closer to it
than I am, and it is a clearly a very complicated subject I just don't
have the time to master; I'm just glad that the traditional diamond
frame works so well. However, in the sequence of science, before you
can know what the formulae mean, you must first discover which are
important and should be given greater weight, and those buggers
haven't yet done that. They don't appear even to have added
significantly to Jones's list of what ISN'T the crucial factor.

I'd be delighted to be convinced otherwise, that they've made a
significant stride, but all I see is academic doclat-filler. The guy
at Batavus has it right: the bicycle in its most developed form, the
racing bike, is somewhere near perfection, developed by tiny advances
in the hands of users, and for a few other bikes for specific
purposes, there will be some fiddling around the edges. I'm not
impressed with these great strides of science: I wrote to my own bike
maker, Utopia, two years ago that they should beware of making the
smaller frames on proportionately shorter wheelbases because a middle-
aged market -- slower riders with slowing reflexes -- will appreciate
the stability of the longer wheelbases, something I discovered by
comparing my three Dutch city bikes and the various wooden geribikes I
experimented with a few years ago. So that's Batavus's big discovery
from this research? Gee, maybe they should talk to their customers
more often.

Sorry to be negative about guys who have the right intention, but
there's nothing new here except a better class of self-promotion for
scientists.

Andre Jute
Visit Jute on Bicycles at
http://coolmainpress.com/BICYCLING.html

On Jul 8, 5:10*pm, Peter Cole wrote:
On 7/8/2011 1:24 PM, Frank Krygowski wrote:

I think having the background knowledge helps. *In my mind, it's like
learning to play an instrument. *We're all hard-wired to know how to
move our fingers; and lots of people get quite good on instruments
without lessons, just bumbling on their own, so to speak.

But a good teacher will give important tips, and will make the student
conscious of aspects of motion that the student might never realize on
his own. *A specific example: "When lifting your finger free [of the
hole, the key, the fret, the string, whatever] try not to raise it so
high. *That will allow you to increase your speed."

Such tips don't increase facility immediately. *But as the student
thinks about them (perhaps subconsciously), internalizes them and
practices them, they do eventually help. *I think the same is true of
certain on-bike moves.

In addition, coaches in any sport engage in the same sort of analyzing
and teaching, and get the athletes do a lot of educated practice. *Few
question that it can be valuable.

- Frank Krygowski

It's not that complicated. Children can do it.

These children can do it:
http://www.youtube.com/watch?v=nKofhkgk7h8

I bet they had a lesson or two, though.

- Frank Krygowski

Peter Cole wrote:
On 7/8/2011 10:17 AM, Winston wrote:

(...)

Depends on one's definition of the term, I suppose.

I don't think there's much to dispute. Counter-steering merely initiates
a fall in the direction you wish to turn. You do that by putting the
tire contact patch to the other side of vertical. You then steer into
the fall, balancing the centripetal and gravitational forces. We do it
all the time, cycling or even walking.

In my part of the world, new riders turn by initially
steering and leaning into the new direction of travel.
I have yet to see a new bicycle rider counter-steer on purpose
(and remain in control).
It is counter-intuitive.

Using the 'counter-steering' technique (to advantage) is different from
the course-deviation that occurs when hitting the chord of
a divot in the road, for example. Both are fast direction changes
prompted by leveraging 'center of gravity'.

I don't understand "chord of a divot" nor "leveraging 'center of gravity'".

A chord of a divot is a groove. A recess.

You leverage 'center of gravity' by (in your words):
"[initiating] a fall in the direction you wish to turn."

The former can get you around a corner quickly and safely.
The latter forces you (however temporarily or slightly) into a
direction you hadn't intended.

The only thing that actually forces me in unintended directions are
grooves, like trolley tracks.

Sure, any groove, recess, divot, curb, etc. can do that.

It's not lectures that help, but
practice. People just don't get much exposure to the need to swerve
suddenly, but it's quite natural, nothing counter-intuitive about it.

I don't understand.
'Steering left' to 'go right' is intuitive?
Can you clarify please?

Sure, being bipeds, we have the need to change the direction of our
momentum (esp when running) with a "contact patch" only at our feet. We
are always dynamically balancing, even when motionless, but when we are
running and need to turn sharply we need to perform exactly the same
maneuver as we do on a bike. It is likely we are born knowing how to do
it. You just have to transfer that innate knowledge to cycling, it's not
something that needs to be taught, just practiced.

Most children get it
right away, otherwise they couldn't ride bikes.

I misunderstand your terminology.
Could you view this clip and tell me if this rider is
turning conventionally or counter-steering, please?

http://www.youtube.com/watch?v=SEDbWVor1b8

Maybe it is one of those 'perception' things, but
I would swear that he is turning and leaning in
the same direction, (into the turn, conventionally).

Do you see any difference between the way he is
turning and the way this rider is turning?:
http://www.youtube.com/watch?v=C848R9xWrjc
(Starting at ~2:36)

I sure do.

It's just a matter of conditioning the reflexes. Mountain biking does
this pretty quickly.

I couldn't agree more (with this first sentence).

When it comes to bike handling skills, mountain biking typically
provides far more frequent situations to develop those skills.

In the same manner that being caged with a wild lion poses
many more opportunities to develop one's lion taming skills
than if one were to relax in front of the tube, for example?

Since it's a matter of reflexive, not book, learning --

The technique of turning the bars in the opposite direction
of intended travel on purpose (counter steering) is, for
most folks terra incognita. We steer and lean 'into' our turns
and for a vast majority of folks, that works just fine for the
entire period spent on two wheels. There is nothing intuitive
about counter-steering, IMVHO.

a more challenging
environment speeds up the process and keeps the skills sharp. In
addition to turning and braking skills, it also improves a broad range
of balance, reaction time, spacial perception capacities -- especially
useful for older riders, as research seems to indicate a very strong
"use it or lose it" phenomenon, particularly with aging.

I think your test subjects self-select, then.

Unlike the unfortunates who crashed because they never learned
how to counter-steer.
http://www.youtube.com/watch?v=leBMU...mbedded#at=527

--Winston

In article ,
Peter Cole wrote:

On 7/7/2011 12:06 PM, Frank Krygowski wrote:
On Jul 7, 11:15 am, wrote:
Tºm Shermªn °_° wrote:


Push hard on the handlebar on the side you want to turn quickly too.

Not 'hard'. That would introduce one to pavement rather quickly.
Experiment first and then practice until it is completely
natural. Counter-steering can be a life-saver.

Standard training in introductory motorcycle riding class.

Yesbut, riding classes are completely optional and
largely ignored. When I sold my last motorcycle, I
demonstrated counter-steering to the new owner by
creating a series of very fast turns down the middle
of my residential street, 'way faster than I could
have done by just leaning.

It was all news to him.

Americans, at least, certainly seem quick to think they know as much
as anyone on any subject at all. Witness things like confident
letters to the editor on topics like economics, international
diplomacy, climate change, etc., written by people who never quite
made it through secondary school.

And on subjects that appear easy, like riding a two-wheeler? Hell,
it's _obvious_ there's nothing to learn! If you can balance, you're
an absolute expert, and nobody can teach you anything!

I've wondered if this overconfidence is connected to America's "all
men created equal" concept. Are things different in countries where
class systems are more blatant? Anybody know?

Jobst used to hypothesize that the biomechanics of counter-steering a
bicycle was similar enough to running that it was a "hard-wired" skill.
The learning curve is nearly instantaneous because we're just
cross-wiring into a skill we're born with. I think all cyclists
counter-steer, most without knowing it. It's not lectures that help, but
practice. People just don't get much exposure to the need to swerve
suddenly, but it's quite natural, nothing counter-intuitive about it.
It's just a matter of conditioning the reflexes. Mountain biking does
this pretty quickly.

Mountain biking is extreme.
Ride your neighborhood streets,
keep a straight line,
keep you eyes on the road,
do not ride over bumps, holes,
or debris and you must then
steer quickly. Presto chango!

--
Michael Press