Gyroscopic forces revisited

[joseph.santaniello@gmail.com]

Hi All,

A while ago there was a thread discussing no-handed riding and the
role gyroscopic forces play in bike turning.

I hypothesized that gyroscopic forces were not that important, and
several things were pointed out to me that almost convinced me. A good
dose of insomnia allowed me to think about this for several hours and
I am now convinced that gyroscopic forces are virtually irrelevant for
riding bikes, hands or no-hands.

It was postulated that a clown-bike with tiny wheel would be difficult
to ride no hands due to the small gyroscopic forces. Since I don't
have a clown-bike to play with, this remains a mystery. But I have
observed little kids riding small wheel (10") bikes at below walking
pace. I have also spun some 12" wheels in my hand a various speeds to
feel what sort of gyroscopic forces are there. Not much. A little kid
with a sense of balance not as developed as an adult can ride one of
these bikes. I do not believe a kid could keep one of these bikes
upright by manual correction alone. These small bikes are stable by
themselves, and since the gyroscopic forces are so low, there must be
something else at work here. This isn't proof or anything, this is
just what got me thinking.

I finally pulled out a big plywood board (much to the chagrin of my
wife who imagines there are myriad things I could be better spending
my time on) and propped it up at an angle and put a bike on it to
simulate what happens when a bike is in a turn. It was suggested that
in a turn a pendulm hung from the top-tube would hang parallel to the
seat tube. When riding no hands in a constant radius turn, this cannot
be the case, and I suspect that it is not the case with hands on the
bars either. Experiments with my plywood board show that when force is
applied straight down through the bike the steering remains straight
no matter what the angle of the board (simulated angle of lean). In a
turn, the steering cannot be straight, otherwise it wouldn't be called
a turn, it would be called a crash. So in a turn (a no-handed one in
particular) something has to be holding the steering at a non-straight
angle. The only thing it can be is that the center of mass is moved to
the side of the plane that is the centerline of the bike. This makes
the steering flop into the turn. The combined force of gravity and the
acceleration of the turn act from the center of mass through the
contact patches of the tires. Since the center of mass is not in the
plane of the bike's centerline, this means that the combined force is
not parallel to the seat tube and thus a pendulum hanging from the top-
tube could not be parallel with the seat tube. Riding with hands on
the bars I suspect is the same. But a rider could force the bike to be
in the same plane, but then they would need to hold the steering at
the proper angle manually. This would no doubt require quite a bit of
skill, and I believe in practice to be virtually impossible. But
perhaps it is just this skill which separates the good from the great.

So what does all that mean? It means that "flop" from an off-center
center of mass is what makes a bike turn, and thus while gyroscopic
forces make help the initial turn of the steering due to induced lean,
it is an unnecessary component that is ultimately irrelevant to turing
a bike.

The whole COM argument was brought about by thinking about how a radio-
controlled motorcycle I used to have woked.

Joseph

[jobst.brandt@stanfordalumni.org]

Joseph Santaniello writes:

> A while ago there was a thread discussing no-handed riding and the
> role gyroscopic forces play in bike turning.

> I hypothesized that gyroscopic forces were not that important, and
> several things were pointed out to me that almost convinced me. A
> good dose of insomnia allowed me to think about this for several
> hours and I am now convinced that gyroscopic forces are virtually
> irrelevant for riding bikes, hands or no-hands.

> It was postulated that a clown-bike with tiny wheel would be
> difficult to ride no hands due to the small gyroscopic forces.
> Since I don't have a clown-bike to play with, this remains a
> mystery. But I have observed little kids riding small wheel (10")
> bikes at below walking pace. I have also spun some 12" wheels in my
> hand a various speeds to feel what sort of gyroscopic forces are
> there. Not much. A little kid with a sense of balance not as
> developed as an adult can ride one of these bikes. I do not believe
> a kid could keep one of these bikes upright by manual correction
> alone. These small bikes are stable by themselves, and since the
> gyroscopic forces are so low, there must be something else at work
> here. This isn't proof or anything, this is just what got me
> thinking.

You should have seen the demo at InterBike where an engineer built a
front wheel with a forward rotating flywheel (brass disk) between
the spokes driven by a small motor at about the speed you expect from
a 27" wheel at 10-15mph. He rode this bicycle no-hands at below 2mph,
steady as a rock, up and down the isles. Without the flywheel
turning independently, the bicycle was as difficult to ride no-hands
as any other bicycle with wheels that size.

> I finally pulled out a big plywood board (much to the chagrin of my
> wife who imagines there are myriad things I could be better spending
> my time on) and propped it up at an angle and put a bike on it to
> simulate what happens when a bike is in a turn. It was suggested
> that in a turn a pendulum hung from the top-tube would hang parallel
> to the seat tube. When riding no hands in a constant radius turn,
> this cannot be the case, and I suspect that it is not the case with
> hands on the bars either. Experiments with my plywood board show
> that when force is applied straight down through the bike the
> steering remains straight no matter what the angle of the board
> (simulated angle of lean). In a turn, the steering cannot be
> straight, otherwise it wouldn't be called a turn, it would be called
> a crash. So in a turn (a no-handed one in particular) something has
> to be holding the steering at a non-straight angle. The only thing
> it can be is that the center of mass is moved to the side of the
> plane that is the centerline of the bike. This makes the steering
> flop into the turn. The combined force of gravity and the
> acceleration of the turn act from the center of mass through the
> contact patches of the tires. Since the center of mass is not in
> the plane of the bike's centerline, this means that the combined
> force is not parallel to the seat tube and thus a pendulum hanging
> from the top- tube could not be parallel with the seat tube. Riding
> with hands on the bars I suspect is the same. But a rider could
> force the bike to be in the same plane, but then they would need to
> hold the steering at the proper angle manually. This would no doubt
> require quite a bit of skill, and I believe in practice to be
> virtually impossible. But perhaps it is just this skill which
> separates the good from the great.

Please discover why one should use paragraphs. You must have come
across this in school.

> So what does all that mean? It means that "flop" from an off-center
> center of mass is what makes a bike turn, and thus while gyroscopic
> forces make help the initial turn of the steering due to induced
> lean, it is an unnecessary component that is ultimately irrelevant
> to turning a bike.

> The whole COM argument was brought about by thinking about how a
> radio controlled motorcycle I used to have worked.

I think your research came up with the wrong result.

An easily repeatable exercise of coasting down a smooth road at more
than 20mph riding no-hands, is to shake one knee from side to side
while resting the other one against the top tube for stability. I
think there is where you will see the effect the best. In addition,
shimmy on a bicycle cannot occur without gyroscopic forces of the
front wheel.

Jobst Brandt

[Jon_C]

How about a wheel on it's own? If you roll a wheel and it leans over
it turns in that direction. The reason is that the contact patch of a
leaning tyre is parallel to the ground and so at an angle to the
wheel's axle so the wheel acts as a rolling cone and turns into the
corner (which maintains it's balance). I'm pretty sure that's the main
steering force involved in no-handed riding.
(I seem to remember reading about someone testing this on a motorbike
and finding that on a prolonged corners the handlebars are actually
turned slightly outward instead of inward as you;d expect. I think
that was due to rake/trail but I don;t have time to think about that
right now :)

[Tom Nakashima]

<joseph.santaniello@gmail.com> wrote in message
news:1193163959.365061.86370@q3g2000prf.googlegrou ps.com...
>
> It was postulated that a clown-bike with tiny wheel would be difficult
> to ride no hands due to the small gyroscopic forces. > Joseph
>

http://www.youtube.com/watch?v=uRvwRgs_ZXE
-tom

[bjw@mambo.ucolick.org]

On Oct 23, 11:25 am, "joseph.santanie...@gmail.com"
<joseph.santanie...@gmail.com> wrote:
> Hi All,
>
> A while ago there was a thread discussing no-handed riding and the
> role gyroscopic forces play in bike turning.
>
> I hypothesized that gyroscopic forces were not that important, and
> several things were pointed out to me that almost convinced me. A good
> dose of insomnia allowed me to think about this for several hours and
> I am now convinced that gyroscopic forces are virtually irrelevant for
> riding bikes, hands or no-hands.
> ....
> So what does all that mean? It means that "flop" from an off-center
> center of mass is what makes a bike turn, and thus while gyroscopic
> forces make help the initial turn of the steering due to induced lean,
> it is an unnecessary component that is ultimately irrelevant to turing
> a bike.

I don't think your experiment tested what you think it tested.

First, gyro inertia experiments were done in a controlled way
by David Jones many years ago. Andrew Muzi alluded to
this. You must read the article at
http://www.phys.lsu.edu/faculty/gonzalez/Teaching/Phys7221/vol59no9p51_56.pdf
He found that the zero-gyro-inertia front wheel (URB 1) was
very difficult to ride no-hands.

Leaning the bike is how you turn at high speed. Go through a
turn at high speed and you'll see that the front wheel is nearly
straight. A bit of countersteer initiates the lean and the turn.
I'm not sure I'd call this a gyroscopic force, because the flop
comes from the steering geometry (fork trail), not from the
gyro force on the wheel. As evidence, I don't think you lean
the bike at a different angle with a heavy tire on the front wheel,
even though that increases the moment of inertia a lot.

Of course, you still lean the bike at low speed, but the allowable
turn of the front wheel is much greater. When riding no hands,
I believe the gyro inertia of the front wheel helps stabilize the
front against excessive flop, and this is why it is more difficult
to ride no-hands at low speed. So the gyro inertia doesn't help
you turn. It helps you not turn.

Ben

[vey]

joseph.santaniello@gmail.com wrote:
> Hi All,
>
> A while ago there was a thread discussing no-handed riding and the
> role gyroscopic forces play in bike turning.

I think it is a COG problem. The bikes I rode that I could ride with no
hands relied less on the speed and more on how high the COG was. These
MTB style bikes have a much higher COG than say, a Dutch commuter bike.

[joseph.santaniello@gmail.com]

On Oct 23, 8:54 pm, jobst.bra...@stanfordalumni.org wrote:
> Joseph Santaniello writes:
> > A while ago there was a thread discussing no-handed riding and the
> > role gyroscopic forces play in bike turning.
> > I hypothesized that gyroscopic forces were not that important, and
> > several things were pointed out to me that almost convinced me. A
> > good dose of insomnia allowed me to think about this for several
> > hours and I am now convinced that gyroscopic forces are virtually
> > irrelevant for riding bikes, hands or no-hands.
> > It was postulated that a clown-bike with tiny wheel would be
> > difficult to ride no hands due to the small gyroscopic forces.
> > Since I don't have a clown-bike to play with, this remains a
> > mystery. But I have observed little kids riding small wheel (10")
> > bikes at below walking pace. I have also spun some 12" wheels in my
> > hand a various speeds to feel what sort of gyroscopic forces are
> > there. Not much. A little kid with a sense of balance not as
> > developed as an adult can ride one of these bikes. I do not believe
> > a kid could keep one of these bikes upright by manual correction
> > alone. These small bikes are stable by themselves, and since the
> > gyroscopic forces are so low, there must be something else at work
> > here. This isn't proof or anything, this is just what got me
> > thinking.
>
> You should have seen the demo at InterBike where an engineer built a
> front wheel with a forward rotating flywheel (brass disk) between
> the spokes driven by a small motor at about the speed you expect from
> a 27" wheel at 10-15mph. He rode this bicycle no-hands at below 2mph,
> steady as a rock, up and down the isles. Without the flywheel
> turning independently, the bicycle was as difficult to ride no-hands
> as any other bicycle with wheels that size.

That sounds like fun! That seems to indicate that the gyroscopic
forces counter the "flop" tendency and keep a bike from turing too
much. I wonder if his gizmo would make a chopper bike rideable no
hands...

>
> > I finally pulled out a big plywood board (much to the chagrin of my
> > wife who imagines there are myriad things I could be better spending
> > my time on) and propped it up at an angle and put a bike on it to
> > simulate what happens when a bike is in a turn. It was suggested
> > that in a turn a pendulum hung from the top-tube would hang parallel
> > to the seat tube. When riding no hands in a constant radius turn,
> > this cannot be the case, and I suspect that it is not the case with
> > hands on the bars either. Experiments with my plywood board show
> > that when force is applied straight down through the bike the
> > steering remains straight no matter what the angle of the board
> > (simulated angle of lean). In a turn, the steering cannot be
> > straight, otherwise it wouldn't be called a turn, it would be called
> > a crash. So in a turn (a no-handed one in particular) something has
> > to be holding the steering at a non-straight angle. The only thing
> > it can be is that the center of mass is moved to the side of the
> > plane that is the centerline of the bike. This makes the steering
> > flop into the turn. The combined force of gravity and the
> > acceleration of the turn act from the center of mass through the
> > contact patches of the tires. Since the center of mass is not in
> > the plane of the bike's centerline, this means that the combined
> > force is not parallel to the seat tube and thus a pendulum hanging
> > from the top- tube could not be parallel with the seat tube. Riding
> > with hands on the bars I suspect is the same. But a rider could
> > force the bike to be in the same plane, but then they would need to
> > hold the steering at the proper angle manually. This would no doubt
> > require quite a bit of skill, and I believe in practice to be
> > virtually impossible. But perhaps it is just this skill which
> > separates the good from the great.
>
> Please discover why one should use paragraphs. You must have come
> across this in school.

Who says I went to school? Ok, I'll try. ;-)


> > So what does all that mean? It means that "flop" from an off-center
> > center of mass is what makes a bike turn, and thus while gyroscopic
> > forces make help the initial turn of the steering due to induced
> > lean, it is an unnecessary component that is ultimately irrelevant
> > to turning a bike.
> > The whole COM argument was brought about by thinking about how a
> > radio controlled motorcycle I used to have worked.
>
> I think your research came up with the wrong result.
>
> An easily repeatable exercise of coasting down a smooth road at more
> than 20mph riding no-hands, is to shake one knee from side to side
> while resting the other one against the top tube for stability. I
> think there is where you will see the effect the best. In addition,
> shimmy on a bicycle cannot occur without gyroscopic forces of the
> front wheel.

I did that very same exercise today on my ride while I was polishing
my theory. I don't argue that gyroscopic forces do not turn the
steering from leaning the bike. I argue that the steering would turn
anyway even if the gyroscopic forces were not there, and that the same
force that would do this turning is the force that holds a bike with
no hands in a constant arc turn.

Joseph

[jim beam]

jobst.brandt@stanfordalumni.org wrote:
<snip for clarity>

> In addition,
> shimmy on a bicycle cannot occur without gyroscopic forces of the
> front wheel.

that's totally untrue. gyro-less, wheel-less ski bikes can shimmy.
shimmy is a dynamic interaction between turn reaction and frame flex -
no gyro forces required.

[Ron Hardin]

The gyroscopic action stabilizes the front wheel, so you need it ;
however it actually works against the countersteer needed for
balancing.

Since there's more mass of the front wheel ahead of the steering tube
line than behind it, if you move the top of the bike sharply _left_
(walking or riding) the front wheel first steers _right_ and
then moves back left. Which produces the necessary countersteer.

It becomes harder and harder to go anywhere but straight as the
speed increases, as the gyroscopic action overrides countersteer.

It becomes harder and harder to balance as the speed decreases, as
the steering continues to turn in the direction its started, there
being diminishing stabilizing gyroscopic action.

There's a range of speeds in the middle where no-handed riding
is easy.
--
rhhardin@mindspring.com

On the internet, nobody knows you're a jerk.

[peteymills@hotmail.com]

On Oct 23, 7:54 pm, jobst.bra...@stanfordalumni.org wrote:
> Joseph Santaniello writes:
> > A while ago there was a thread discussing no-handed riding and the
> > role gyroscopic forces play in bike turning.
> > I hypothesized that gyroscopic forces were not that important, and
> > several things were pointed out to me that almost convinced me. A
> > good dose of insomnia allowed me to think about this for several
> > hours and I am now convinced that gyroscopic forces are virtually
> > irrelevant for riding bikes, hands or no-hands.
> > It was postulated that a clown-bike with tiny wheel would be
> > difficult to ride no hands due to the small gyroscopic forces.
> > Since I don't have a clown-bike to play with, this remains a
> > mystery. But I have observed little kids riding small wheel (10")
> > bikes at below walking pace. I have also spun some 12" wheels in my
> > hand a various speeds to feel what sort of gyroscopic forces are
> > there. Not much. A little kid with a sense of balance not as
> > developed as an adult can ride one of these bikes. I do not believe
> > a kid could keep one of these bikes upright by manual correction
> > alone. These small bikes are stable by themselves, and since the
> > gyroscopic forces are so low, there must be something else at work
> > here. This isn't proof or anything, this is just what got me
> > thinking.
>
> You should have seen the demo at InterBike where an engineer built a
> front wheel with a forward rotating flywheel (brass disk) between
> the spokes driven by a small motor at about the speed you expect from
> a 27" wheel at 10-15mph. He rode this bicycle no-hands at below 2mph,
> steady as a rock, up and down the isles. Without the flywheel
> turning independently, the bicycle was as difficult to ride no-hands
> as any other bicycle with wheels that size.
>
Ah, but was the disc spinning in the same direction as the wheel or in
the opposite direction?
>
>
> > I finally pulled out a big plywood board (much to the chagrin of my
> > wife who imagines there are myriad things I could be better spending
> > my time on) and propped it up at an angle and put a bike on it to
> > simulate what happens when a bike is in a turn. It was suggested
> > that in a turn a pendulum hung from the top-tube would hang parallel
> > to the seat tube. When riding no hands in a constant radius turn,
> > this cannot be the case, and I suspect that it is not the case with
> > hands on the bars either. Experiments with my plywood board show
> > that when force is applied straight down through the bike the
> > steering remains straight no matter what the angle of the board
> > (simulated angle of lean). In a turn, the steering cannot be
> > straight, otherwise it wouldn't be called a turn, it would be called
> > a crash. So in a turn (a no-handed one in particular) something has
> > to be holding the steering at a non-straight angle. The only thing
> > it can be is that the center of mass is moved to the side of the
> > plane that is the centerline of the bike. This makes the steering
> > flop into the turn. The combined force of gravity and the
> > acceleration of the turn act from the center of mass through the
> > contact patches of the tires. Since the center of mass is not in
> > the plane of the bike's centerline, this means that the combined
> > force is not parallel to the seat tube and thus a pendulum hanging
> > from the top- tube could not be parallel with the seat tube. Riding
> > with hands on the bars I suspect is the same. But a rider could
> > force the bike to be in the same plane, but then they would need to
> > hold the steering at the proper angle manually. This would no doubt
> > require quite a bit of skill, and I believe in practice to be
> > virtually impossible. But perhaps it is just this skill which
> > separates the good from the great.
>
> Please discover why one should use paragraphs. You must have come
> across this in school.
>
> > So what does all that mean? It means that "flop" from an off-center
> > center of mass is what makes a bike turn, and thus while gyroscopic
> > forces make help the initial turn of the steering due to induced
> > lean, it is an unnecessary component that is ultimately irrelevant
> > to turning a bike.
> > The whole COM argument was brought about by thinking about how a
> > radio controlled motorcycle I used to have worked.
>
> I think your research came up with the wrong result.
>
> An easily repeatable exercise of coasting down a smooth road at more
> than 20mph riding no-hands, is to shake one knee from side to side
> while resting the other one against the top tube for stability. I
> think there is where you will see the effect the best. In addition,
> shimmy on a bicycle cannot occur without gyroscopic forces of the
> front wheel.
>
> Jobst Brandt

[A Muzi]

Jon_C wrote:
> How about a wheel on it's own? If you roll a wheel and it leans over
> it turns in that direction. The reason is that the contact patch of a
> leaning tyre is parallel to the ground and so at an angle to the
> wheel's axle so the wheel acts as a rolling cone and turns into the
> corner (which maintains it's balance). I'm pretty sure that's the main
> steering force involved in no-handed riding.
> (I seem to remember reading about someone testing this on a motorbike
> and finding that on a prolonged corners the handlebars are actually
> turned slightly outward instead of inward as you;d expect. I think
> that was due to rake/trail but I don;t have time to think about that
> right now :)

David Jones' paper titled 'unrideable bicycle' discusses all that.

I could not find a link (mine's paper) but a search shows 15+ sites with
identical phrasing, entertaining for plagiarism buffs.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

[jobst.brandt@stanfordalumni.org]

Jon Crouch writes:

> How about a wheel on it's own? If you roll a wheel and it leans over
> it turns in that direction. The reason is that the contact patch of
> a leaning tyre is parallel to the ground and so at an angle to the
> wheel's axle so the wheel acts as a rolling cone and turns into the
> corner (which maintains it's balance). I'm pretty sure that's the
> main steering force involved in no-handed riding.

> (I seem to remember reading about someone testing this on a
> motorbike and finding that on a prolonged corners the handlebars are
> actually turned slightly outward instead of inward as you;d
> expect. I think that was due to rake/trail but I don;t have time to
> think about that right now :)

I think you ought to go to a velodrome. These tracks have sloped
straights and more steeply banked circular curves at each end. Riders
have no problem riding no-hands on these tracks, either on the
straight sections or in the banked curve (if they are going fast
enough to not strike a pedal).

If you don't have a track, try a crowned paved street and notice how
the angle with the pavement has essentially no effect on steering, the
centerline of the contact patch moving less than 1/8" off center for a
10° side slope.

Jobst Brandt

[jobst.brandt@stanfordalumni.org]

Joseph Santaniello writes:

>>> A while ago there was a thread discussing no-handed riding and the
>>> role gyroscopic forces play in bike turning. I hypothesized that
>>> gyroscopic forces were not that important, and several things were
>>> pointed out to me that almost convinced me. A good dose of
>>> insomnia allowed me to think about this for several hours and I am
>>> now convinced that gyroscopic forces are virtually irrelevant for
>>> riding bikes, hands or no-hands. It was postulated that a
>>> clown-bike with tiny wheel would be difficult to ride no hands due
>>> to the small gyroscopic forces. Since I don't have a clown-bike
>>> to play with, this remains a mystery. But I have observed little
>>> kids riding small wheel (10") bikes at below walking pace. I have
>>> also spun some 12" wheels in my hand a various speeds to feel what
>>> sort of gyroscopic forces are there. Not much. A little kid with
>>> a sense of balance not as developed as an adult can ride one of
>>> these bikes. I do not believe a kid could keep one of these bikes
>>> upright by manual correction alone. These small bikes are stable
>>> by themselves, and since the gyroscopic forces are so low, there
>>> must be something else at work here. This isn't proof or
>>> anything, this is just what got me thinking.

>> You should have seen the demo at InterBike where an engineer built
>> a front wheel with a forward rotating flywheel (brass disk) between
>> the spokes driven by a small motor at about the speed you expect
>> from a 27" wheel at 10-15mph. He rode this bicycle no-hands at
>> below 2mph, steady as a rock, up and down the isles. Without the
>> flywheel turning independently, the bicycle was as difficult to
>> ride no-hands as any other bicycle with wheels that size.

> That sounds like fun! That seems to indicate that the gyroscopic
> forces counter the "flop" tendency and keep a bike from turning too
> much. I wonder if his gizmo would make a chopper bike ridable no
> hands...

You are grasping at straws. The gyroscopic effect of the flywheel
made the bicycle handle as though it were traveling above 10mph, a
speed at which riding no hands is easy because there are gyroscopic
steering forces available to the rider.

>>> I finally pulled out a big plywood board (much to the chagrin of
>>> my wife who imagines there are myriad things I could be better
>>> spending my time on) and propped it up at an angle and put a bike
>>> on it to simulate what happens when a bike is in a turn. It was
>>> suggested that in a turn a pendulum hung from the top-tube would
>>> hang parallel to the seat tube. When riding no hands in a
>>> constant radius turn, this cannot be the case, and I suspect that
>>> it is not the case with hands on the bars either. Experiments
>>> with my plywood board show that when force is applied straight
>>> down through the bike the steering remains straight no matter what
>>> the angle of the board (simulated angle of lean). In a turn, the
>>> steering cannot be straight, otherwise it wouldn't be called a
>>> turn, it would be called a crash. So in a turn (a no-handed one
>>> in particular) something has to be holding the steering at a
>>> non-straight angle. The only thing it can be is that the center
>>> of mass is moved to the side of the plane that is the centerline
>>> of the bike. This makes the steering flop into the turn. The
>>> combined force of gravity and the acceleration of the turn act
>>> from the center of mass through the contact patches of the tires.
>>> Since the center of mass is not in the plane of the bike's
>>> centerline, this means that the combined force is not parallel to
>>> the seat tube and thus a pendulum hanging from the top- tube could
>>> not be parallel with the seat tube. Riding with hands on the bars
>>> I suspect is the same. But a rider could force the bike to be in
>>> the same plane, but then they would need to hold the steering at
>>> the proper angle manually. This would no doubt require quite a
>>> bit of skill, and I believe in practice to be virtually
>>> impossible. But perhaps it is just this skill which separates the
>>> good from the great.

>> Please discover why one should use paragraphs. You must have come
>> across this in school.

> Who says I went to school? OK, I'll try. ;-)

>>> So what does all that mean? It means that "flop" from an
>>> off-center center of mass is what makes a bike turn, and thus
>>> while gyroscopic forces make help the initial turn of the steering
>>> due to induced lean, it is an unnecessary component that is
>>> ultimately irrelevant to turning a bike. The whole COM argument
>>> was brought about by thinking about how a radio controlled
>>> motorcycle I used to have worked.

>> I think your research came up with the wrong result.

>> An easily repeatable exercise of coasting down a smooth road at
>> more than 20mph riding no-hands, is to shake one knee from side to
>> side while resting the other one against the top tube for
>> stability. I think there is where you will see the effect the
>> best. In addition, shimmy on a bicycle cannot occur without
>> gyroscopic forces of the front wheel.

> I did that very same exercise today on my ride while I was polishing
> my theory. I don't argue that gyroscopic forces do not turn the
> steering from leaning the bike. I argue that the steering would
> turn anyway even if the gyroscopic forces were not there, and that
> the same force that would do this turning is the force that holds a
> bike with no hands in a constant arc turn.

Well, try riding no-hands at 2mph (less than walking speed). To what
do you attribute the inability to steer the bicycle at such a speed?

Just try moving one knee side-to-side and see what steering you get at
those speeds.

Jobst Brandt

[joseph.santaniello@gmail.com]

On Oct 23, 9:41 pm, "Tom Nakashima" <t...@slac.stanford.edu> wrote:
> <joseph.santanie...@gmail.com> wrote in message
>
> news:1193163959.365061.86370@q3g2000prf.googlegrou ps.com...
>
>
>
> > It was postulated that a clown-bike with tiny wheel would be difficult
> > to ride no hands due to the small gyroscopic forces. > Joseph
>
> http://www.youtube.com/watch?v=uRvwRgs_ZXE
> -tom

Do you think this robot being able to ride a bike at super slow speeds
with obviously entirely manual steering correction is evidence that a
clown bike is difficult to ride no hands, or not so difficult?

Joseph

[Tom Nakashima]

<joseph.santaniello@gmail.com> wrote in message
news:1193172557.232179.68820@v23g2000prn.googlegro ups.com...
> On Oct 23, 9:41 pm, "Tom Nakashima" <t...@slac.stanford.edu> wrote:
>> <joseph.santanie...@gmail.com> wrote in message
>>
>> news:1193163959.365061.86370@q3g2000prf.googlegrou ps.com...
>>
>>
>>
>> > It was postulated that a clown-bike with tiny wheel would be difficult
>> > to ride no hands due to the small gyroscopic forces. > Joseph
>>
>> http://www.youtube.com/watch?v=uRvwRgs_ZXE
>> -tom
>
> Do you think this robot being able to ride a bike at super slow speeds
> with obviously entirely manual steering correction is evidence that a
> clown bike is difficult to ride no hands, or not so difficult?
>
> Joseph
>

The hardest part the designers had to deal with robot riding the bike is
balance. The engineers installed a gyro sensor that detects angular
velocity and inclination, then transmit the data to a computer that adjust
the robot's balance.

Someone tried to ride a clown's bike with mini wheels and published an
article in one of the bicycle magazines. Said they had a hard time keeping
their balance. I believe it was a contest to see if anyone could ride it a
100 ft. without putting their foot down. Nobody was able to do it.
-tom

[clare at snyder.on.ca]

On Tue, 23 Oct 2007 13:49:17 -0700, "joseph.santaniello@gmail.com"
<joseph.santaniello@gmail.com> wrote:

>On Oct 23, 9:41 pm, "Tom Nakashima" <t...@slac.stanford.edu> wrote:
>> <joseph.santanie...@gmail.com> wrote in message
>>
>> news:1193163959.365061.86370@q3g2000prf.googlegrou ps.com...
>>
>>
>>
>> > It was postulated that a clown-bike with tiny wheel would be difficult
>> > to ride no hands due to the small gyroscopic forces. > Joseph
>>
>> http://www.youtube.com/watch?v=uRvwRgs_ZXE
>> -tom
>
>Do you think this robot being able to ride a bike at super slow speeds
>with obviously entirely manual steering correction is evidence that a
>clown bike is difficult to ride no hands, or not so difficult?
>
>Joseph
What was in the robot's backpack? I'm betting there was a gyro
somewhere.

--
Posted via a free Usenet account from http://www.teranews.com

[jobst.brandt@stanfordalumni.org]

Tom Nakashima writes:

>>>> It was postulated that a clown-bike with tiny wheel would be
>>>> difficult to ride no hands due to the small gyroscopic forces. >
>>>> Joseph

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

>> Do you think this robot being able to ride a bike at super slow
>> speeds with obviously entirely manual steering correction is
>> evidence that a clown bike is difficult to ride no hands, or not so
>> difficult?

> The hardest part the designers had to deal with robot riding the
> bike is balance. The engineers installed a gyro sensor that detects
> angular velocity and inclination, then transmit the data to a
> computer that adjust the robot's balance.

> Someone tried to ride a clown's bike with mini wheels and published
> an article in one of the bicycle magazines. Said they had a hard
> time keeping their balance. I believe it was a contest to see if
> anyone could ride it a 100 ft. without putting their foot down.
> Nobody was able to do it.

I think this is all over the hill stuff because Segway has a product
and it is being used in some odd places, such as for flatfoots
cruising the downtown sidewalks. Balance there uses gyroscopes in
two directions.

http://ai-depot.com/Robotics/112.html
http://www.segway.com/

Jobst Brandt

[joseph.santaniello@gmail.com]

On Oct 23, 11:05 pm, "Tom Nakashima" <t...@slac.stanford.edu> wrote:
> <joseph.santanie...@gmail.com> wrote in message
>
> news:1193172557.232179.68820@v23g2000prn.googlegro ups.com...
>
>
>
> > On Oct 23, 9:41 pm, "Tom Nakashima" <t...@slac.stanford.edu> wrote:
> >> <joseph.santanie...@gmail.com> wrote in message
>
> >>news:1193163959.365061.86370@q3g2000prf.googlegrou ps.com...
>
> >> > It was postulated that a clown-bike with tiny wheel would be difficult
> >> > to ride no hands due to the small gyroscopic forces. > Joseph
>
> >>http://www.youtube.com/watch?v=uRvwRgs_ZXE
> >> -tom
>
> > Do you think this robot being able to ride a bike at super slow speeds
> > with obviously entirely manual steering correction is evidence that a
> > clown bike is difficult to ride no hands, or not so difficult?
>
> > Joseph
>
> The hardest part the designers had to deal with robot riding the bike is
> balance. The engineers installed a gyro sensor that detects angular
> velocity and inclination, then transmit the data to a computer that adjust
> the robot's balance.
>
> Someone tried to ride a clown's bike with mini wheels and published an
> article in one of the bicycle magazines. Said they had a hard time keeping
> their balance. I believe it was a contest to see if anyone could ride it a
> 100 ft. without putting their foot down. Nobody was able to do it.
> -tom

That may have been some problem with the geometry of the clown bike.
I've seen 2 people riding those crazy fold-up bikes with what looks
like roller-blade wheels and a belt drive, and they seemed to be doing
just fine. I was in a car both times, so I didn't have the oppurtunity
to investigate further.

Joseph

[Doc O'Leary]

In article <fflnm0$ko5$1@news.Stanford.EDU>,
"Tom Nakashima" <tom@slac.stanford.edu> wrote:

> Someone tried to ride a clown's bike with mini wheels and published an
> article in one of the bicycle magazines. Said they had a hard time keeping
> their balance. I believe it was a contest to see if anyone could ride it a
> 100 ft. without putting their foot down. Nobody was able to do it.

I'm not sure what that has to do with gyroscopic forces. Something like
the A-bike seems quite able to be balanced with mini wheels, likely for
the same reason (higher center of gravity) that it's easy to balance a
broom on your fingertip but not the dustpan.

--
My personal UDP list: 127.0.0.1, 4ax.com, buzzardnews.com, googlegroups.com,
heapnode.com, localhost, ntli.net, teranews.com, vif.com, x-privat.org

[Tom Nakashima]

<clare at snyder.on.ca> wrote in message
news:469th3hkg09vi47ss3jqjv67r3nle42678@4ax.com...
> On Tue, 23 Oct 2007 13:49:17 -0700, "joseph.santaniello@gmail.com"
> <joseph.santaniello@gmail.com> wrote:
>
>>On Oct 23, 9:41 pm, "Tom Nakashima" <t...@slac.stanford.edu> wrote:
>>> <joseph.santanie...@gmail.com> wrote in message
>>>
>>> news:1193163959.365061.86370@q3g2000prf.googlegrou ps.com...
>>>
>>>
>>>
>>> > It was postulated that a clown-bike with tiny wheel would be difficult
>>> > to ride no hands due to the small gyroscopic forces. > Joseph
>>>
>>> http://www.youtube.com/watch?v=uRvwRgs_ZXE
>>> -tom
>>
>>Do you think this robot being able to ride a bike at super slow speeds
>>with obviously entirely manual steering correction is evidence that a
>>clown bike is difficult to ride no hands, or not so difficult?
>>
>>Joseph
> What was in the robot's backpack? I'm betting there was a gyro
> somewhere.

Not sure what's in the robot's backpack, the computer?
The gyroscopic sensor is in robot's stomach, makes sense to balance the CG.
Another video showing the robot riding the bike in circles, you can clearly
seen the gyroscopic sensors.
http://www.youtube.com/watch?v=Srwk-i5aXRQ
enjoy,
-tom

[Jon_C]

On Oct 23, 10:51 pm, jobst.bra...@stanfordalumni.org wrote:
> Jon Crouch writes:
> > How about a wheel on it's own? If you roll a wheel and it leans over
> > it turns in that direction. The reason is that the contact patch of
> > a leaning tyre is parallel to the ground and so at an angle to the
> > wheel's axle so the wheel acts as a rolling cone and turns into the
> > corner (which maintains it's balance). I'm pretty sure that's the
> > main steering force involved in no-handed riding.
> > (I seem to remember reading about someone testing this on a
> > motorbike and finding that on a prolonged corners the handlebars are
> > actually turned slightly outward instead of inward as you;d
> > expect. I think that was due to rake/trail but I don;t have time to
> > think about that right now :)
>
> I think you ought to go to a velodrome. These tracks have sloped
> straights and more steeply banked circular curves at each end. Riders
> have no problem riding no-hands on these tracks, either on the
> straight sections or in the banked curve (if they are going fast
> enough to not strike a pedal).
>
> If you don't have a track, try a crowned paved street and notice how
> the angle with the pavement has essentially no effect on steering, the
> centerline of the contact patch moving less than 1/8" off center for a
> 10° side slope.
>
> Jobst Brandt

To go in a straight line on an angled surface you'd have to keep the
steering pointed slightly down the slope (ie. left on a velodrome
straight) to counter-act the steering force from the slope. Maybe a
slight weave-like cycle occurs where the rightward steering force from
the slope causes the rider to 'fall' left (centrifugal force) which
causes the bike to steer back to the left and so on. Aslo, shifting
the rider's center of gravity to the right will lean the bike frame to
the left slightly, causing the front wheel to 'flop' (and steer) left
countering camber thrust from the slope.

I don't think the 1/8" offset of the contact patch is too relevant
btw. Camber thrust is due the angle between the wheel's axle and the
ground (cone effect) not contact patch offset.

[Tom Nakashima]

<jobst.brandt@stanfordalumni.org> wrote in message
news:471eb316$0$14121$742ec2ed@news.sonic.net...

>I think you ought to go to a velodrome. These tracks have sloped
>straights and more steeply banked circular curves at each end. Riders
>have no problem riding no-hands on these tracks, either on the
>straight sections or in the banked curve (if they are going fast
>enough to not strike a pedal).

>If you don't have a track, try a crowned paved street and notice how
>the angle with the pavement has essentially no effect on steering, the
centerline of the contact patch moving less than 1/8" off center for a
>10° side slope.
>Jobst Brandt

I think I may be able to answer this one.
I was talking with co-worker Timothy Montagne who just got back from the
track Nationals in Trexlertown, Pennsylvania. I forget the exact slope on
the straights in degrees, but he told me it was so steep that you have to
keep a minimum speed of 20 mph. or else you would fall over. So I can
imagine your speed has to be greater than 20 mph to be able to ride with no
hands, of course which is no problem with a track rider.

When I ride the San Jose velodrome, I have no problem riding with no hands,
but the slope is mild. I'm sure a min. speed is needed, just never crossed
my mind.

I'm riding with Tim today after work, so I can pick his brains more on the
banked track.
-tom

[joseph.santaniello@gmail.com]

On Oct 24, 4:59 am, jobst.bra...@stanfordalumni.org wrote:
> Well, try riding no-hands at 2mph (less than walking speed). To what
> do you attribute the inability to steer the bicycle at such a speed?
>
> Just try moving one knee side-to-side and see what steering you get at
> those speeds.

I just did that (took video too!) and it was as expected easy to ride
at a fast pace, difficult but not impossible at a walking pace, and
virtually impossible slower. Side to side knee movement at speed
produces little effect, at walking has a very large effect, and at sub
walking speed is not wise with double toe straps!

So gyroscopic forces provide stability to the bike by resisting
steering changes induced by lean. And of course gyroscipic forces also
contibute to steering changes when the axis of rotation is tilted by
leaning quickly.

But a bike stays in a turn when the center of mass is outside of the
center-line of the bike. This is why a riderless bike goes straight
(more or less). If it doesn't go dead straight it is probably
alignment or maybe even the off-center center of mass due to the
drivetrain. My son helped me with some "ghost-rider" tests on some of
our too-small kids bikes. Inconclusive as to whether they always end
up going to the same side.

If you tape a brick to the side of the seatpost of a bike and send it
off on a riderless mission, it turns as the COM is off center and this
combined with the steering geometry means the steering flops to the
side. Gyroscopic forces keep it stable in this turn, just as they keep
it stable in a straight line with no brick.

So gyroscopic forces are necessary to keep a bike in a stable state,
whether a straight ahead, or a constant arc turn. They keep the
steering from making too twitchy changes, but they are not exclusively
what makes the turn happen, nor what keep the steering at the proper
angle during a turn.

Joseph

[Jambo]

"jim beam" <spamvortex@bad.example.net> wrote in message
news:feydnbYx3IW4IoPanZ2dnUVZ_ofinZ2d@speakeasy.ne t...
> jobst.brandt@stanfordalumni.org wrote:
> <snip for clarity>
>
>> In addition,
>> shimmy on a bicycle cannot occur without gyroscopic forces of the
>> front wheel.
>
> that's totally untrue. gyro-less, wheel-less ski bikes can shimmy. shimmy
> is a dynamic interaction between turn reaction and frame flex - no gyro
> forces required.

That's totally bull****. "Turn reaction"? Please.

Shimmy cannot occur on skis - no matter where they are mounted, bikes or
snow mobiles. Interaction with the ground cannot induce resonant vibration
on anything other than rotating components, unless travelling at superhuman
speed. But you wouldn't know this from your "metarials skool", would you?
Idiot.

[Jasper Janssen]

On Wed, 24 Oct 2007 01:18:04 -0400, "Jambo" <-@-.-> wrote:

>Shimmy cannot occur on skis - no matter where they are mounted, bikes or
>snow mobiles. Interaction with the ground cannot induce resonant vibration
>on anything other than rotating components, unless travelling at superhuman
>speed. But you wouldn't know this from your "metarials skool", would you?
>Idiot.

Why would a ski not be able to resonate if some surface irregularity
manages to hit a resonance at a certain speed?

Jasper

[jobst.brandt@stanfordalumni.org]

Joseph Santaniello writes:

>> Well, try riding no-hands at 2mph (less than walking speed). To
>> what do you attribute the inability to steer the bicycle at such a
>> speed?

>> Just try moving one knee side-to-side and see what steering you get
>> at those speeds.

> I just did that (took video too!) and it was as expected easy to
> ride at a fast pace, difficult but not impossible at a walking pace,
> and virtually impossible slower. Side to side knee movement at
> speed produces little effect, at walking has a very large effect,
> and at sub walking speed is not wise with double toe straps!

> So gyroscopic forces provide stability to the bike by resisting
> steering changes induced by lean. And of course gyroscopic forces
> also contribute to steering changes when the axis of rotation is
> tilted by leaning quickly.

You can try that by holding a front wheel in your hands and not that
the steer reaction to tilting a spinning wheel is faster the slower the
rotation rate but the force to tilt the axis is also smaller. When
coasting downhill no-hands steering works well the greater the speed.
It just doesn't react as fast, but then that is what you want anyway
or you would crash in a hurry.

> But a bike stays in a turn when the center of mass is outside of the
> center-line of the bike. This is why a riderless bike goes straight
> (more or less). If it doesn't go dead straight it is probably
> alignment or maybe even the off-center center of mass due to the
> drivetrain. My son helped me with some "ghost-rider" tests on some
> of our too-small kids bikes. Inconclusive as to whether they always
> end up going to the same side.

I think that experiment doesn't demonstrate the relationship between
gyroscopic forces and rider control by moving the hips to steer. That
movement is, in essence, one that doesn't occur on a riderless
bicycle.

> If you tape a brick to the side of the seatpost of a bike and send
> it off on a riderless mission, it turns as the COM is off center and
> this combined with the steering geometry means the steering flops to
> the side. Gyroscopic forces keep it stable in this turn, just as
> they keep it stable in a straight line with no brick.

> So gyroscopic forces are necessary to keep a bike in a stable state,
> whether a straight ahead, or a constant arc turn. They keep the
> steering from making too twitchy changes, but they are not
> exclusively what makes the turn happen, nor what keep the steering
> at the proper angle during a turn.

As I said, the faster it turns the slower the response.

Jobst Brandt

[joseph.santaniello@gmail.com]

On Oct 24, 1:49 pm, Doc O'Leary <droleary.use...@4q2007.subsume.com>
wrote:
> In article <fflnm0$ko...@news.Stanford.EDU>,
> "Tom Nakashima" <t...@slac.stanford.edu> wrote:
>
> > Someone tried to ride a clown's bike with mini wheels and published an
> > article in one of the bicycle magazines. Said they had a hard time keeping
> > their balance. I believe it was a contest to see if anyone could ride it a
> > 100 ft. without putting their foot down. Nobody was able to do it.
>
> I'm not sure what that has to do with gyroscopic forces. Something like
> the A-bike seems quite able to be balanced with mini wheels, likely for
> the same reason (higher center of gravity) that it's easy to balance a
> broom on your fingertip but not the dustpan.
>

I think we need to define "clown-bike" here. For me a clown bike is
one with tiny wheels and short wheelbase, but reasonable normal seat
and bar height. Picture a 12" kids' BMX with a huge seatpost and riser
bars. Is that what you guys think of?

Joseph

[Tom Nakashima]

<joseph.santaniello@gmail.com> wrote in message
news:1193227131.128703.71040@t8g2000prg.googlegrou ps.com...

> I think we need to define "clown-bike" here.
> Joseph

http://www.pranks4u.com/media/brian02bike.72.jpg
-tom

[joseph.santaniello@gmail.com]

On Oct 24, 2:40 pm, Jon_C <JonCCro...@gmail.com> wrote:
> On Oct 23, 10:51 pm, jobst.bra...@stanfordalumni.org wrote:
>
>
>
> > Jon Crouch writes:
> > > How about a wheel on it's own? If you roll a wheel and it leans over
> > > it turns in that direction. The reason is that the contact patch of
> > > a leaning tyre is parallel to the ground and so at an angle to the
> > > wheel's axle so the wheel acts as a rolling cone and turns into the
> > > corner (which maintains it's balance). I'm pretty sure that's the
> > > main steering force involved in no-handed riding.
> > > (I seem to remember reading about someone testing this on a
> > > motorbike and finding that on a prolonged corners the handlebars are
> > > actually turned slightly outward instead of inward as you;d
> > > expect. I think that was due to rake/trail but I don;t have time to
> > > think about that right now :)
>
> > I think you ought to go to a velodrome. These tracks have sloped
> > straights and more steeply banked circular curves at each end. Riders
> > have no problem riding no-hands on these tracks, either on the
> > straight sections or in the banked curve (if they are going fast
> > enough to not strike a pedal).
>
> > If you don't have a track, try a crowned paved street and notice how
> > the angle with the pavement has essentially no effect on steering, the
> > centerline of the contact patch moving less than 1/8" off center for a
> > 10° side slope.
>
> > Jobst Brandt
>
> To go in a straight line on an angled surface you'd have to keep the
> steering pointed slightly down the slope (ie. left on a velodrome
> straight) to counter-act the steering force from the slope. Maybe a
> slight weave-like cycle occurs where the rightward steering force from
> the slope causes the rider to 'fall' left (centrifugal force) which
> causes the bike to steer back to the left and so on. Aslo, shifting
> the rider's center of gravity to the right will lean the bike frame to
> the left slightly, causing the front wheel to 'flop' (and steer) left
> countering camber thrust from the slope.
>
> I don't think the 1/8" offset of the contact patch is too relevant
> btw. Camber thrust is due the angle between the wheel's axle and the
> ground (cone effect) not contact patch offset.

I don't think you do need have the steering anything but straight on a
sloped surface. Not having a velodrome handy, that's why I broke out
my trusty plywood board. I too thought the angle of the wheels on the
surface had something to do with it, but it doesn't. I put my bike on
the board and fiddled with it quite a bit, and the angle of contact
alone does not appear to matter. What does matter is where the center
of mass is relative to the contact patches and the combined gravity
and turn forces. When the center of mass is along the centerline of
the bike and these forces are acting through it to the patches, the
steering satys straight no matter the angle of the wheels to the road.

Using a sloped board you can simulate the forces on a riderless bike
during a turn. (On Mars...)

Perhaps some minimum speed is necessary to not fall over riding on a
sloped velodrome, but I suspect this is from requiring a certain
amount of momentum to be able to "climb" the banking everytime you
make a steering correction up-track.

Joseph

[Tim McNamara]

In article <ffnhg2$n2$1@news.Stanford.EDU>,
"Tom Nakashima" <tom@slac.stanford.edu> wrote:

> I was talking with co-worker Timothy Montagne who just got back from
> the track Nationals in Trexlertown, Pennsylvania. I forget the exact
> slope on the straights in degrees, but he told me it was so steep
> that you have to keep a minimum speed of 20 mph. or else you would
> fall over. So I can imagine your speed has to be greater than 20 mph
> to be able to ride with no hands, of course which is no problem with
> a track rider.

Timothy sold you a line of malarkey. If he was right, then the
sprinters couldn't do track stands or pace each other at 2-3 mph up and
down the track. But they can and Timothy is wrong.

[jobst.brandt@stanfordalumni.org]

Tom Nakashima writes:

>> I think you ought to go to a velodrome. These tracks have sloped
>> straights and more steeply banked circular curves at each end.
>> Riders have no problem riding no-hands on these tracks, either on
>> the straight sections or in the banked curve (if they are going
>> fast enough to not strike a pedal).

>> If you don't have a track, try a crowned paved street and notice
>> how the angle with the pavement has essentially no effect on
>> steering, the centerline of the contact patch moving less than 1/8"
>> off center for a 10? side slope.

> I think I may be able to answer this one. I was talking with
> co-worker Timothy Montagne who just got back from the track
> Nationals in Trexlertown, Pennsylvania. I forget the exact slope on
> the straights in degrees, but he told me it was so steep that you
> have to keep a minimum speed of 20 mph. or else you would fall
> over. So I can imagine your speed has to be greater than 20 mph to
> be able to ride with no hands, of course which is no problem with a
> track rider.

I think there was a misunderstanding there. The speed is required to
keep from grounding a pedal on steep bankings (as I mentioned) but has
nothing to do with riding no-hands on the straights, which is like
riding no-hands on a flat surface. The difference being that turns
upslope respond slightly differently from turns downslope.

> When I ride the San Jose velodrome, I have no problem riding with no
> hands, but the slope is mild. I'm sure a minimum speed is needed,
> just never crossed my mind.

That's because it isn't any different than on a level course.

> I'm riding with Tim today after work, so I can pick his brains more
> on the banked track.

Jobst Brandt

[sl]

In article <ffnhg2$n2$1@news.Stanford.EDU>,
Tom Nakashima <tom@slac.stanford.edu> wrote:
>
><jobst.brandt@stanfordalumni.org> wrote in message
>news:471eb316$0$14121$742ec2ed@news.sonic.net...
>
>>I think you ought to go to a velodrome. These tracks have sloped
>>straights and more steeply banked circular curves at each end. Riders
>>have no problem riding no-hands on these tracks, either on the
>>straight sections or in the banked curve (if they are going fast
>>enough to not strike a pedal).
>
>>If you don't have a track, try a crowned paved street and notice how
>>the angle with the pavement has essentially no effect on steering, the
>centerline of the contact patch moving less than 1/8" off center for a
>>10° side slope.
>>Jobst Brandt
>
>I think I may be able to answer this one.
>I was talking with co-worker Timothy Montagne who just got back from the
>track Nationals in Trexlertown, Pennsylvania. I forget the exact slope on
>the straights in degrees, but he told me it was so steep that you have to
>keep a minimum speed of 20 mph. or else you would fall over. So I can
>imagine your speed has to be greater than 20 mph to be able to ride with no
>hands, of course which is no problem with a track rider.

I ride at Burnaby Velodrome, 200m wooden track, 47 degrees at the
steepest part of the curve.

It is difficult to stay on in the curve at anything under 30kph.

We routinely see new riders slide off from going to slow. As recently
as yesterday morning.

[Michael Press]

In article <ffnie6$1dj$1@news.Stanford.EDU>,
"Tom Nakashima" <tom@slac.stanford.edu> wrote:

> <joseph.santaniello@gmail.com> wrote in message
> news:1193227131.128703.71040@t8g2000prg.googlegrou ps.com...
>
> > I think we need to define "clown-bike" here.
> > Joseph
>
> http://www.pranks4u.com/media/brian02bike.72.jpg

Front wheel fork offset is rearward
as on a grocery cart.

--
Michael Press

[velodancer]

> I think we need to define "clown-bike" here.

Without defining a clown bike, their use is walking speed or below,
the most difficult speed to ride any bike no hands. At speeds higher
than walking, these bikes may be very close to regular bikes in the
ability to balance no hands.

While it has been a while since I've been in college, I would expect
gyroscopic forces to have a direct relationship to the linear speed of
the wheel (at the tire contact) and the effective rotating mass at the
tire contact. Thus a small wheel with the same effective mass as a
larger wheel, will exhibit the exact same gyroscopic effect as the
larger wheel.

Small wheel bikes generally have faster handling than larger wheeled
bikes. I believe that much of it is due to the shorter contact patch
along the line of direction, but the smaller radius also means that
the wheel will fall into a turn with greater acceleration. This
lowered forward stability for me seems to make a small wheeled bike
easier to ride no hands at a significantly lower speed than a larger
wheeled bike (no experience below 16"). I've noticed this surprising
experience a number of times over the last 20 years. I will say that
most find it harder to ride small wheel bikes no hands at any speed,
but I conjecture that this is because they are not used to the faster
handling.

I have the same experience on large wheeled bikes with faster
handling, I can ride them slower no hands. Recumbents, due their
typically low COG, are significantly harder to ride no hands. I've
never been able to do it at speeds under 10 miles an hour and even
then it can be very difficult to impossible depending on the model.

[Tom Nakashima]

"Tim McNamara" <timmcn@bitstream.net> wrote in message
news:timmcn-C6BB21.09172624102007@news.iphouse.com...
> In article <ffnhg2$n2$1@news.Stanford.EDU>,
> "Tom Nakashima" <tom@slac.stanford.edu> wrote:
>
>> I was talking with co-worker Timothy Montagne who just got back from
>> the track Nationals in Trexlertown, Pennsylvania. I forget the exact
>> slope on the straights in degrees, but he told me it was so steep
>> that you have to keep a minimum speed of 20 mph. or else you would
>> fall over. So I can imagine your speed has to be greater than 20 mph
>> to be able to ride with no hands, of course which is no problem with
>> a track rider.
>
> Timothy sold you a line of malarkey. If he was right, then the
> sprinters couldn't do track stands or pace each other at 2-3 mph up and
> down the track. But they can and Timothy is wrong.

Timothy Montagne is pretty straight forward, never caught him in a lie.
However, I can't say that about reading some of your post.
You can read about Montagne here:
http://today.slac.stanford.edu/a/2007/10-01.htm
-tom

[Tim McNamara]

In article <ffnl8j$3uh$1@news.Stanford.EDU>,
"Tom Nakashima" <tom@slac.stanford.edu> wrote:

> "Tim McNamara" <timmcn@bitstream.net> wrote in message
> news:timmcn-C6BB21.09172624102007@news.iphouse.com...
> > In article <ffnhg2$n2$1@news.Stanford.EDU>, "Tom Nakashima"
> > <tom@slac.stanford.edu> wrote:
> >
> >> I was talking with co-worker Timothy Montagne who just got back
> >> from the track Nationals in Trexlertown, Pennsylvania. I forget
> >> the exact slope on the straights in degrees, but he told me it was
> >> so steep that you have to keep a minimum speed of 20 mph. or else
> >> you would fall over. So I can imagine your speed has to be greater
> >> than 20 mph to be able to ride with no hands, of course which is
> >> no problem with a track rider.
> >
> > Timothy sold you a line of malarkey. If he was right, then the
> > sprinters couldn't do track stands or pace each other at 2-3 mph up
> > and down the track. But they can and Timothy is wrong.
>
> Timothy Montagne is pretty straight forward, never caught him in a
> lie. However, I can't say that about reading some of your post.

What do you think I have lied about, Tom? Is it a lie that sprinters
can do track stands on a velodrome? Is it a lie that they pace each
other at very low speeds while jockeying for advantage, without falling
off the track (usually)? If you're going to accuse me of lying, have
the courtesy to back it up.

Unfortunately the Lehigh Valley Velodrome Web site doesn't contain the
specs for the track. The local track here, the national Sports Center
velodrome in Blaine MN, is a wooden 250 m track with 43 degree banking
in the corners. It's quite possible on that track to ride below 10 mph
if you know how to keep your pedals from striking the banking on the
uptrack side. I've seen riders come to a halt in the corners. I've
seen sprinters do track stands. According to:

http://www.geocities.com/lvvelodrome/Velodrome.html

The Lehigh Valley Velodrome has a maximum banking of 28 degrees. There
is no reason whatsoever for a minimum speed of 20 mph on a track that
flat, unless the surface is particularly slippery. Since that velodrome
is concrete, that seems unlikely.

> You can read about Montagne here:
> http://today.slac.stanford.edu/a/2007/10-01.htm

Thanks for the link.

[vey]

joseph.santaniello@gmail.com wrote:

> Using a sloped board you can simulate the forces on a riderless bike
> during a turn. (On Mars...)

I tried an experiment today. On a flat surface, I haven't been able to
ride without hands since I retired my old three speed years ago. Since
then, I've been riding flatbars and if I let go I would just about crash
right then and there. Today, I was able to do it easily.

Two weeks ago I converted an old flatbar into an upright, higher stem,
bars that come back, B-66 saddle. Now, miraculously, I can ride with no
hands. When I tried with the flatbar, I had to shift my body up and back
because I was leaning so far forward, but if I am already up and back,
like I am now, I just let go and I am fine.

No difference in wheel size, no difference in speed, but big difference
in COG. COG is not just height, but longitudinal and lateral weight,
too, or so I was told when I had to make such calculations.

[Jon_C]

On Oct 24, 11:04 am, "joseph.santanie...@gmail.com"
<joseph.santanie...@gmail.com> wrote:
> On Oct 24, 2:40 pm, Jon_C <JonCCro...@gmail.com> wrote:
>
>
>
> > On Oct 23, 10:51 pm, jobst.bra...@stanfordalumni.org wrote:
>
> > > Jon Crouch writes:
> > > > How about a wheel on it's own? If you roll a wheel and it leans over
> > > > it turns in that direction. The reason is that the contact patch of
> > > > a leaning tyre is parallel to the ground and so at an angle to the
> > > > wheel's axle so the wheel acts as a rolling cone and turns into the
> > > > corner (which maintains it's balance). I'm pretty sure that's the
> > > > main steering force involved in no-handed riding.
> > > > (I seem to remember reading about someone testing this on a
> > > > motorbike and finding that on a prolonged corners the handlebars are
> > > > actually turned slightly outward instead of inward as you;d
> > > > expect. I think that was due to rake/trail but I don;t have time to
> > > > think about that right now :)
>
> > > I think you ought to go to a velodrome. These tracks have sloped
> > > straights and more steeply banked circular curves at each end. Riders
> > > have no problem riding no-hands on these tracks, either on the
> > > straight sections or in the banked curve (if they are going fast
> > > enough to not strike a pedal).
>
> > > If you don't have a track, try a crowned paved street and notice how
> > > the angle with the pavement has essentially no effect on steering, the
> > > centerline of the contact patch moving less than 1/8" off center for a
> > > 10° side slope.
>
> > > Jobst Brandt
>
> > To go in a straight line on an angled surface you'd have to keep the
> > steering pointed slightly down the slope (ie. left on a velodrome
> > straight) to counter-act the steering force from the slope. Maybe a
> > slight weave-like cycle occurs where the rightward steering force from
> > the slope causes the rider to 'fall' left (centrifugal force) which
> > causes the bike to steer back to the left and so on. Aslo, shifting
> > the rider's center of gravity to the right will lean the bike frame to
> > the left slightly, causing the front wheel to 'flop' (and steer) left
> > countering camber thrust from the slope.
>
> > I don't think the 1/8" offset of the contact patch is too relevant
> > btw. Camber thrust is due the angle between the wheel's axle and the
> > ground (cone effect) not contact patch offset.
>
> I don't think you do need have the steering anything but straight on a
> sloped surface. Not having a velodrome handy, that's why I broke out
> my trusty plywood board. I too thought the angle of the wheels on the
> surface had something to do with it, but it doesn't. I put my bike on
> the board and fiddled with it quite a bit, and the angle of contact
> alone does not appear to matter. What does matter is where the center
> of mass is relative to the contact patches and the combined gravity
> and turn forces. When the center of mass is along the centerline of
> the bike and these forces are acting through it to the patches, the
> steering satys straight no matter the angle of the wheels to the road.
>
> Using a sloped board you can simulate the forces on a riderless bike
> during a turn. (On Mars...)
>
> Perhaps some minimum speed is necessary to not fall over riding on a
> sloped velodrome, but I suspect this is from requiring a certain
> amount of momentum to be able to "climb" the banking everytime you
> make a steering correction up-track.
>
> Joseph


Joseph, your experiment fails because your bike is stationary on the
board. Camber thrust is a turning force caused by a wheel _rolling_ on
a surface it's not perpendicular to (rolling cone effect). It's
impossible to create camber thrust with a stationary wheel.
http://picasaweb.google.com/JonCCrouch/UntitledAlbum/photo#5125629114602972546

Also by being stationary you're eliminating the the effect of wheel
drag which, combined with trail (shopping cart wheel effect) gives the
wheel a tendency to point straight ahead and combined with an offset
contact patch (when leaning) give the wheel a tendency to turn inwards.

[velodancer]

On Oct 24, 2:26 pm, vey <jun...@ericvey.com> wrote:

> Two weeks ago I converted an old flatbar into an upright, higher stem,
> bars that come back, B-66 saddle. Now, miraculously, I can ride with no
> hands. When I tried with the flatbar, I had to shift my body up and back
> because I was leaning so far forward, but if I am already up and back,
> like I am now, I just let go and I am fine.
>
> No difference in wheel size, no difference in speed, but big difference
> in COG. COG is not just height, but longitudinal and lateral weight,
> too, or so I was told when I had to make such calculations.

This is more likely a skill issue in simultaneously letting go of your
hands while also repositioning your body. It is much easier to
initiate no hands if your fingertips are just resting lightly on the
handlebars rather than supporting weight. While you are correct that
the higher COG does make a difference, it is the same COG riding no
hands no matter where the bars are placed (after all, you are not
using them).

[joseph.santaniello@gmail.com]

On Oct 24, 11:26 pm, vey <jun...@ericvey.com> wrote:
> joseph.santanie...@gmail.com wrote:
> > Using a sloped board you can simulate the forces on a riderless bike
> > during a turn. (On Mars...)
>
> I tried an experiment today. On a flat surface, I haven't been able to
> ride without hands since I retired my old three speed years ago. Since
> then, I've been riding flatbars and if I let go I would just about crash
> right then and there. Today, I was able to do it easily.
>
> Two weeks ago I converted an old flatbar into an upright, higher stem,
> bars that come back, B-66 saddle. Now, miraculously, I can ride with no
> hands. When I tried with the flatbar, I had to shift my body up and back
> because I was leaning so far forward, but if I am already up and back,
> like I am now, I just let go and I am fine.
>
> No difference in wheel size, no difference in speed, but big difference
> in COG. COG is not just height, but longitudinal and lateral weight,
> too, or so I was told when I had to make such calculations.

I think the difference is practice. As you get more comfortable riding
no hands you will be able to do the transition easier. I'm sure it was
the upper body movement during the transfer that was the culprit, not
the placement of the COG.

Joseph

[joseph.santaniello@gmail.com]

On Oct 25, 12:00 am, velodancer <commerc...@yahoo.com> wrote:
> On Oct 24, 2:26 pm, vey <jun...@ericvey.com> wrote:
>
> > Two weeks ago I converted an old flatbar into an upright, higher stem,
> > bars that come back, B-66 saddle. Now, miraculously, I can ride with no
> > hands. When I tried with the flatbar, I had to shift my body up and back
> > because I was leaning so far forward, but if I am already up and back,
> > like I am now, I just let go and I am fine.
>
> > No difference in wheel size, no difference in speed, but big difference
> > in COG. COG is not just height, but longitudinal and lateral weight,
> > too, or so I was told when I had to make such calculations.
>
> This is more likely a skill issue in simultaneously letting go of your
> hands while also repositioning your body. It is much easier to
> initiate no hands if your fingertips are just resting lightly on the
> handlebars rather than supporting weight. While you are correct that
> the higher COG does make a difference, it is the same COG riding no
> hands no matter where the bars are placed (after all, you are not
> using them).

The COG can move when riding no hands vs with the bars. On my bike my
upper body is leaned forward at maybe 45deg and my arms are forward
some amount when I ride holding the bars. If I want I can ride no
hands by just letting go and keeping my body leaned over, but that
isn't too comfortable. So I sit up with my upper body vertical and
arms to the side. I'm sure this moves the COG at least 20cm or so.

But I agree that the COG placement probably isn't the cause of his
previous difficulties.

Joseph

[Tim McNamara]

In article <BQQTi.140654$1y4.11487@pd7urf2no>,
sl@whiskey.enposte.net (sl) wrote:

> In article <ffnhg2$n2$1@news.Stanford.EDU>, Tom Nakashima
> <tom@slac.stanford.edu> wrote:
> >
> ><jobst.brandt@stanfordalumni.org> wrote in message
> >news:471eb316$0$14121$742ec2ed@news.sonic.net...
> >
> >>I think you ought to go to a velodrome. These tracks have sloped
> >>straights and more steeply banked circular curves at each end.
> >>Riders have no problem riding no-hands on these tracks, either on
> >>the straight sections or in the banked curve (if they are going
> >>fast enough to not strike a pedal).
> >
> >>If you don't have a track, try a crowned paved street and notice
> >>how the angle with the pavement has essentially no effect on
> >>steering, the
> >centerline of the contact patch moving less than 1/8" off center for
> >a
> >>10° side slope. Jobst Brandt
> >
> >I think I may be able to answer this one. I was talking with
> >co-worker Timothy Montagne who just got back from the track
> >Nationals in Trexlertown, Pennsylvania. I forget the exact slope on
> >the straights in degrees, but he told me it was so steep that you
> >have to keep a minimum speed of 20 mph. or else you would fall over.
> >So I can imagine your speed has to be greater than 20 mph to be able
> >to ride with no hands, of course which is no problem with a track
> >rider.
>
> I ride at Burnaby Velodrome, 200m wooden track, 47 degrees at the
> steepest part of the curve.
>
> It is difficult to stay on in the curve at anything under 30kph.
>
> We routinely see new riders slide off from going to slow. As recently
> as yesterday morning.

And yet sprinters can ride the entire lap, at any lateral position, at
literally a walking pace. So that disproves the claim that you have to
go at least 30 kph. I've ridden many times at the local wooden
velodrome (Blaine MN, 250 m, 43 degree banks in corners) as slow as 10
mph. It is necessary to tilt the bike deliberately to the inside to
avoid striking a pedal on the up-track side- failure to do so is
probably what is causing your new riders to fall off. I have seen
riders come to a complete stop in mid-corner without falling off.

Perhaps proper slow cornering technique ought to be added to the
introductory class. You do have an introductory class for new riders,
right? It would reduce the number of crashing newbies.

[Tom Nakashima]

"sl" <sl@whiskey.enposte.net> wrote in message
news:BQQTi.140654$1y4.11487@pd7urf2no...
> In article <ffnhg2$n2$1@news.Stanford.EDU>,
> Tom Nakashima <tom@slac.stanford.edu> wrote:
>>
>><jobst.brandt@stanfordalumni.org> wrote in message
>>news:471eb316$0$14121$742ec2ed@news.sonic.net...
>>
>>>I think you ought to go to a velodrome. These tracks have sloped
>>>straights and more steeply banked circular curves at each end. Riders
>>>have no problem riding no-hands on these tracks, either on the
>>>straight sections or in the banked curve (if they are going fast
>>>enough to not strike a pedal).
>>
>>>If you don't have a track, try a crowned paved street and notice how
>>>the angle with the pavement has essentially no effect on steering, the
>>centerline of the contact patch moving less than 1/8" off center for a
>>>10° side slope.
>>>Jobst Brandt
>>
>>I think I may be able to answer this one.
>>I was talking with co-worker Timothy Montagne who just got back from the
>>track Nationals in Trexlertown, Pennsylvania. I forget the exact slope on
>>the straights in degrees, but he told me it was so steep that you have to
>>keep a minimum speed of 20 mph. or else you would fall over. So I can
>>imagine your speed has to be greater than 20 mph to be able to ride with
>>no
>>hands, of course which is no problem with a track rider.
>
> I ride at Burnaby Velodrome, 200m wooden track, 47 degrees at the
> steepest part of the curve.
>
> It is difficult to stay on in the curve at anything under 30kph.
>
> We routinely see new riders slide off from going to slow. As recently
> as yesterday morning.
>

That sounds about right, 30kph would be 18.64114 mph.
-tom

[jobst.brandt@stanfordalumni.org]

Tim McNamara writes:

>>>> I think you ought to go to a velodrome. These tracks have sloped
>>>> straights and more steeply banked circular curves at each end.
>>>> Riders have no problem riding no-hands on these tracks, either on
>>>> the straight sections or in the banked curve (if they are going
>>>> fast enough to not strike a pedal).

>>>> If you don't have a track, try a crowned paved street and notice
>>>> how the angle with the pavement has essentially no effect on
>>>> steering, the centerline of the contact patch moving less than
>>>> 1/8" off center for a 10 degree side slope.

>>> I think I may be able to answer this one. I was talking with
>>> co-worker Timothy Montagne who just got back from the track
>>> Nationals in Trexlertown, Pennsylvania. I forget the exact slope
>>> on the straights in degrees, but he told me it was so steep that
>>> you have to keep a minimum speed of 20 mph, or else you would
>>> fall. So I can imagine your speed has to be greater than 20 mph
>>> to be able to ride with no hands, of course which is no problem
>>> with a track rider.

>> I ride at Burnaby Velodrome, 200m wooden track, 47 degrees at the
>> steepest part of the curve.

>> It is difficult to stay on in the curve at anything under 30kph.

>> We routinely see new riders slide off from going to slow. As
>> recently as yesterday morning.

> And yet sprinters can ride the entire lap, at any lateral position,
> at literally a walking pace. So that disproves the claim that you
> have to go at least 30 kph.

This is magic. Just try leaning a track bicycle to 47 degrees with
the pedal down at its lowest position and you'll note that it strikes
the ground at far less than that angle. Grounding a pedal in the
curved bankings on most tracks is a known hazard. If you believe one
can ride at walking speed (bicycle vertical) I must assume you haven't
tried it at speeds just under the natural pedal clearance speed.

> I've ridden many times at the local wooden velodrome (Blaine MN,
> 250m, 43 degree banks in corners) as slow as 10 mph. It is
> necessary to tilt the bike deliberately to the inside to avoid
> striking a pedal on the up-track side- failure to do so is probably
> what is causing your new riders to fall off. I have seen riders
> come to a complete stop in mid-corner without falling off.

So you are not riding the bicycle seated as on does on a track except
when accelerating. Beyond that, we are talking about riding no-hands.
It requires some gymnastics to ride at moderate speeds hands-on, on
steeply banked tracks and that is what was claimed. I have watched
six-day racers on the Frankfurt (D) indoor track fall off the banking
when traffic got too slow. It is damn hard to do your "lean the
bicycle" stunt at moderate speeds with hands-on and even harder to do
it no-hands.

> Perhaps proper slow cornering technique ought to be added to the
> introductory class. You do have an introductory class for new
> riders, right? It would reduce the number of crashing newbies.

Not at all. There is little purpose to that, slowness not being part
of track racing. Besides, it doesn't work reliably at moderate speeds
where cadence makes tilting the bicycle a hit or miss event of
synchronizing the bottom of the right crank with enough lean.

Jobst Brandt

[Tom Nakashima]

"Tim McNamara" <timmcn@bitstream.net> wrote in message
news:timmcn-9FFEAC.20423324102007@news.iphouse.com...
>
> Perhaps proper slow cornering technique ought to be added to the
> introductory class. You do have an introductory class for new riders,
> right? It would reduce the number of crashing newbies.

As a track rider I'm surprised you don't know that most crashes on the
track are due to the inexperience of riding in a tight pack.
I've seen riders panic, stop pedaling, touch the rear wheel of the bike in
front of them. It isn't until one becomes experienced in track riding that
the newbie's become at ease. When I get back on my roadbike after
riding the track, everything seems like slow motion.

Try riding with no hands at 5 mph on the straights of a banked track next
time you're out there.
-tom

[Tom Nakashima]

"Tim McNamara" <timmcn@bitstream.net> wrote in message
news:timmcn-205F17.20571424102007@news.iphouse.com...
> In article <ffnl8j$3uh$1@news.Stanford.EDU>,
> "Tom Nakashima" <tom@slac.stanford.edu> wrote:
>
>> "Tim McNamara" <timmcn@bitstream.net> wrote in message
>> news:timmcn-C6BB21.09172624102007@news.iphouse.com...
>> > In article <ffnhg2$n2$1@news.Stanford.EDU>, "Tom Nakashima"
>> > <tom@slac.stanford.edu> wrote:
>> >
>> >> I was talking with co-worker Timothy Montagne who just got back
>> >> from the track Nationals in Trexlertown, Pennsylvania. I forget
>> >> the exact slope on the straights in degrees, but he told me it was
>> >> so steep that you have to keep a minimum speed of 20 mph. or else
>> >> you would fall over. So I can imagine your speed has to be greater
>> >> than 20 mph to be able to ride with no hands, of course which is
>> >> no problem with a track rider.
>> >
>> > Timothy sold you a line of malarkey. If he was right, then the
>> > sprinters couldn't do track stands or pace each other at 2-3 mph up
>> > and down the track. But they can and Timothy is wrong.
>>
>> Timothy Montagne is pretty straight forward, never caught him in a
>> lie. However, I can't say that about reading some of your post.
>
> What do you think I have lied about, Tom? Is it a lie that sprinters
> can do track stands on a velodrome? Is it a lie that they pace each
> other at very low speeds while jockeying for advantage, without falling
> off the track (usually)? If you're going to accuse me of lying, have
> the courtesy to back it up.

We're talking about riding with "no-hands" on the straight section of a
steep banked track.
I would love to see you ride with "no-hands" at 2-3mph on the straight
section of a steep banked track.
Make a video and post it!
-tom

[sl]

In article <timmcn-205F17.20571424102007@news.iphouse.com>,
Tim McNamara <timmcn@bitstream.net> wrote:
>In article <ffnl8j$3uh$1@news.Stanford.EDU>,
> "Tom Nakashima" <tom@slac.stanford.edu> wrote:
>
>> "Tim McNamara" <timmcn@bitstream.net> wrote in message
>> news:timmcn-C6BB21.09172624102007@news.iphouse.com...
>> > In article <ffnhg2$n2$1@news.Stanford.EDU>, "Tom Nakashima"
>> > <tom@slac.stanford.edu> wrote:
>> >
>> >> I was talking with co-worker Timothy Montagne who just got back
>> >> from the track Nationals in Trexlertown, Pennsylvania. I forget
>> >> the exact slope on the straights in degrees, but he told me it was
>> >> so steep that you have to keep a minimum speed of 20 mph. or else
>> >> you would fall over. So I can imagine your speed has to be greater
>> >> than 20 mph to be able to ride with no hands, of course which is
>> >> no problem with a track rider.
>> >
>> > Timothy sold you a line of malarkey. If he was right, then the
>> > sprinters couldn't do track stands or pace each other at 2-3 mph up
>> > and down the track. But they can and Timothy is wrong.
>>
>> Timothy Montagne is pretty straight forward, never caught him in a
>> lie. However, I can't say that about reading some of your post.
>
>What do you think I have lied about, Tom? Is it a lie that sprinters
>can do track stands on a velodrome? Is it a lie that they pace each
>other at very low speeds while jockeying for advantage, without falling
>off the track (usually)? If you're going to accuse me of lying, have
>the courtesy to back it up.

Track stands and riding slow are possible, but if you watch a track
sprint where they are doing it you'll notice that they angle the wheels
to compensate.

Sliding off happens when you don't compensate for the lack of
centrifugal force by doing something else.

[Tim McNamara]

In article <47202838$0$14103$742ec2ed@news.sonic.net>,
jobst.brandt@stanfordalumni.org wrote:

> Tim McNamara writes:
>
> >>>> I think you ought to go to a velodrome. These tracks have
> >>>> sloped straights and more steeply banked circular curves at each
> >>>> end. Riders have no problem riding no-hands on these tracks,
> >>>> either on the straight sections or in the banked curve (if they
> >>>> are going fast enough to not strike a pedal).
>
> >>>> If you don't have a track, try a crowned paved street and notice
> >>>> how the angle with the pavement has essentially no effect on
> >>>> steering, the centerline of the contact patch moving less than
> >>>> 1/8" off center for a 10 degree side slope.
>
> >>> I think I may be able to answer this one. I was talking with
> >>> co-worker Timothy Montagne who just got back from the track
> >>> Nationals in Trexlertown, Pennsylvania. I forget the exact slope
> >>> on the straights in degrees, but he told me it was so steep that
> >>> you have to keep a minimum speed of 20 mph, or else you would
> >>> fall. So I can imagine your speed has to be greater than 20 mph
> >>> to be able to ride with no hands, of course which is no problem
> >>> with a track rider.
>
> >> I ride at Burnaby Velodrome, 200m wooden track, 47 degrees at the
> >> steepest part of the curve.
>
> >> It is difficult to stay on in the curve at anything under 30kph.
>
> >> We routinely see new riders slide off from going to slow. As
> >> recently as yesterday morning.
>
> > And yet sprinters can ride the entire lap, at any lateral position,
> > at literally a walking pace. So that disproves the claim that you
> > have to go at least 30 kph.
>
> This is magic. Just try leaning a track bicycle to 47 degrees with
> the pedal down at its lowest position and you'll note that it strikes
> the ground at far less than that angle. Grounding a pedal in the
> curved bankings on most tracks is a known hazard. If you believe one
> can ride at walking speed (bicycle vertical) I must assume you
> haven't tried it at speeds just under the natural pedal clearance
> speed.

As noted below, I have tried it albeit on a track with a maximum banking
of 43 degrees (which would be definitely different than a track with
banking at 47 degrees). Leaning the bike away from the track while
riding slowly is not difficult and I don't know why you would think that
it is. We were taught this technique on the first day of track
orientation. The more difficult thing is holding a line at slow speeds
against gravity. I've also been taken off the track by two different
riders who struck a pedal above me and came down like bowling pins.

New or inexperienced riders tend to have to go faster to avoid these
things. Skilled track riders can go slower without getting into
trouble. I was only able to ride as slow as 10 mph, but I also never
developed more than moderate skills at best at track racing. The Cat
1/2 riders could ride much slower when the situation demanded it.

> > I've ridden many times at the local wooden velodrome (Blaine MN,
> > 250m, 43 degree banks in corners) as slow as 10 mph. It is
> > necessary to tilt the bike deliberately to the inside to avoid
> > striking a pedal on the up-track side- failure to do so is probably
> > what is causing your new riders to fall off. I have seen riders
> > come to a complete stop in mid-corner without falling off.
>
> So you are not riding the bicycle seated as on does on a track except
> when accelerating. Beyond that, we are talking about riding
> no-hands. It requires some gymnastics to ride at moderate speeds
> hands-on, on steeply banked tracks and that is what was claimed. I
> have watched six-day racers on the Frankfurt (D) indoor track fall
> off the banking when traffic got too slow. It is damn hard to do
> your "lean the bicycle" stunt at moderate speeds with hands-on and
> even harder to do it no-hands.

Hands-off, I can't do it. When I've seen riders riding no handed around
the velodrome they've been going at moderate speeds- say 18-20 mph.
Hands-on is a different story. I watched national caliber sprinters
ride up and down the banks at a walking pace during the strategic
portion of sprint events. It can be done. Of course, the steeper the
banking the harder it is and the higher the minimum speed will be. Very
short tracks- under 200 m- tend to have very steep banks- the portable
indoor track that circulated around the US a few years ago had 53 degree
banks. 42 to 43 degrees is pretty typical on a 250 meter track. Larger
tracks like Northbrook (33 m and 10 degrees IIRC) or Trexlertown (333 m
and 28 degrees) tend to have shallower banking.

> > Perhaps proper slow cornering technique ought to be added to the
> > introductory class. You do have an introductory class for new
> > riders, right? It would reduce the number of crashing newbies.
>
> Not at all. There is little purpose to that, slowness not being part
> of track racing. Besides, it doesn't work reliably at moderate
> speeds where cadence makes tilting the bicycle a hit or miss event of
> synchronizing the bottom of the right crank with enough lean.

You've not watched match sprints? I find that hard to believe. Slow
riding is very much a part of that event. Sprint bikes also have very
high bottom brackets- more so than track bikes designed for other
events- which reduces the pedal strike problem somewhat.

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

Great trackstand demonstration as well as good slow speed riding.

[jobst.brandt@stanfordalumni.org]

Joseph Santaniello writes:

>>> Two weeks ago I converted an old flatbar into an upright, higher
>>> stem, bars that come back, B-66 saddle. Now, miraculously, I can
>>> ride with no hands. When I tried with the flatbar, I had to shift
>>> my body up and back because I was leaning so far forward, but if I
>>> am already up and back, like I am now, I just let go and I am
>>> fine.

>>> No difference in wheel size, no difference in speed, but big
>>> difference in COG. COG is not just height, but longitudinal and
>>> lateral weight, too, or so I was told when I had to make such
>>> calculations.

>> This is more likely a skill issue in simultaneously letting go of
>> your hands while also repositioning your body. It is much easier
>> to initiate no hands if your fingertips are just resting lightly on
>> the handlebars rather than supporting weight. While you are
>> correct that the higher COG does make a difference, it is the same
>> COG riding no hands no matter where the bars are placed (after all,
>> you are not using them).

> The COG can move when riding no hands vs with the bars. On my bike
> my upper body is leaned forward at maybe 45deg and my arms are
> forward some amount when I ride holding the bars. If I want I can
> ride no hands by just letting go and keeping my body leaned over,
> but that isn't too comfortable. So I sit up with my upper body
> vertical and arms to the side. I'm sure this moves the COG at least
> 20cm or so.

> But I agree that the COG placement probably isn't the cause of his
> previous difficulties.

As I mentioned in the past, all my relatively straight top speed
descents are done essentially no-hands, at speeds at times exceeding
60mph. At such times my hands are on the bar stem, elbows on knees
that are against the top tube and my back as low as I can get without
my chin bouncing on my hands. If there is no cross wind, this is a
highly stable position in which I can lean steeply into corners.

Steering is done by moving my upper body to either side of center, the
motion being slight and not apparent to an observer on a following
bicycle. It is in this position that "countersteer" is most apparent
because taking curves must be done by first leaning out of the turn
and then neutralizing that motion by returning to center.

Jobst Brandt

[joseph.santaniello@gmail.com]

On Oct 25, 9:15 am, jobst.bra...@stanfordalumni.org wrote:
> Joseph Santaniello writes:
> >>> Two weeks ago I converted an old flatbar into an upright, higher
> >>> stem, bars that come back, B-66 saddle. Now, miraculously, I can
> >>> ride with no hands. When I tried with the flatbar, I had to shift
> >>> my body up and back because I was leaning so far forward, but if I
> >>> am already up and back, like I am now, I just let go and I am
> >>> fine.
> >>> No difference in wheel size, no difference in speed, but big
> >>> difference in COG. COG is not just height, but longitudinal and
> >>> lateral weight, too, or so I was told when I had to make such
> >>> calculations.
> >> This is more likely a skill issue in simultaneously letting go of
> >> your hands while also repositioning your body. It is much easier
> >> to initiate no hands if your fingertips are just resting lightly on
> >> the handlebars rather than supporting weight. While you are
> >> correct that the higher COG does make a difference, it is the same
> >> COG riding no hands no matter where the bars are placed (after all,
> >> you are not using them).
> > The COG can move when riding no hands vs with the bars. On my bike
> > my upper body is leaned forward at maybe 45deg and my arms are
> > forward some amount when I ride holding the bars. If I want I can
> > ride no hands by just letting go and keeping my body leaned over,
> > but that isn't too comfortable. So I sit up with my upper body
> > vertical and arms to the side. I'm sure this moves the COG at least
> > 20cm or so.
> > But I agree that the COG placement probably isn't the cause of his
> > previous difficulties.
>
> As I mentioned in the past, all my relatively straight top speed
> descents are done essentially no-hands, at speeds at times exceeding
> 60mph. At such times my hands are on the bar stem, elbows on knees
> that are against the top tube and my back as low as I can get without
> my chin bouncing on my hands. If there is no cross wind, this is a
> highly stable position in which I can lean steeply into corners.
>
> Steering is done by moving my upper body to either side of center, the
> motion being slight and not apparent to an observer on a following
> bicycle. It is in this position that "countersteer" is most apparent
> because taking curves must be done by first leaning out of the turn
> and then neutralizing that motion by returning to center.
>
> Jobst Brandt

I have witnessed descending in a similar fashion, but with both hands
behind the rider's butt. This position is significantly more
aerodynamic, as evidenced by the riders marked speed increase upon
moving the arms back like that.

When you are cornering tight turns like a hairpin, do you make
conscious manual adjustments to your steering angle?

Joseph

[jobst.brandt@stanfordalumni.org]

Joseph Santaniello writes:

>>>>> Two weeks ago I converted an old flatbar into an upright, higher
>>>>> stem, bars that come back, B-66 saddle. Now, miraculously, I can
>>>>> ride with no hands. When I tried with the flatbar, I had to shift
>>>>> my body up and back because I was leaning so far forward, but if I
>>>>> am already up and back, like I am now, I just let go and I am
>>>>> fine.

>>>>> No difference in wheel size, no difference in speed, but big
>>>>> difference in COG. COG is not just height, but longitudinal and
>>>>> lateral weight, too, or so I was told when I had to make such
>>>>> calculations.

>>>> This is more likely a skill issue in simultaneously letting go of
>>>> your hands while also repositioning your body. It is much easier
>>>> to initiate no hands if your fingertips are just resting lightly on
>>>> the handlebars rather than supporting weight. While you are
>>>> correct that the higher COG does make a difference, it is the same
>>>> COG riding no hands no matter where the bars are placed (after all,
>>>> you are not using them).

>>> The COG can move when riding no hands vs with the bars. On my bike
>>> my upper body is leaned forward at maybe 45deg and my arms are
>>> forward some amount when I ride holding the bars. If I want I can
>>> ride no hands by just letting go and keeping my body leaned over,
>>> but that isn't too comfortable. So I sit up with my upper body
>>> vertical and arms to the side. I'm sure this moves the COG at least
>>> 20cm or so.

>>> But I agree that the COG placement probably isn't the cause of his
>>> previous difficulties.

>> As I mentioned in the past, all my relatively straight top speed
>> descents are done essentially no-hands, at speeds at times exceeding
>> 60mph. At such times my hands are on the bar stem, elbows on knees
>> that are against the top tube and my back as low as I can get without
>> my chin bouncing on my hands. If there is no cross wind, this is a
>> highly stable position in which I can lean steeply into corners.

>> Steering is done by moving my upper body to either side of center, the
>> motion being slight and not apparent to an observer on a following
>> bicycle. It is in this position that "countersteer" is most apparent
>> because taking curves must be done by first leaning out of the turn
>> and then neutralizing that motion by returning to center.

> I have witnessed descending in a similar fashion, but with both
> hands behind the rider's butt. This position is significantly more
> aerodynamic, as evidenced by the riders marked speed increase upon
> moving the arms back like that.

I doubt that this does what you say it does because frontal area is
what causes drag, the closing area behind the rider being a bluff body
and has no streamlining (as a long pointed tail). Frontal area is
smaller with the shoulders pulled in in front of the rider with arms in
chest, elbows on knees.

> When you are cornering tight turns like a hairpin, do you make
> conscious manual adjustments to your steering angle?

I don't understand what you mean by steering angle. All turns are
made with countersteer whether running, ice skating, snowboarding or
bicycling. These are all balanced modes of motion and follow the same
principles.

http://www.sheldonbrown.com/brandt/descending.html

Jobst Brandt

[Tim McNamara]

In article <ffq7bn$3mm$1@news.Stanford.EDU>,
"Tom Nakashima" <tom@slac.stanford.edu> wrote:

> "Tim McNamara" <timmcn@bitstream.net> wrote in message
> news:timmcn-9FFEAC.20423324102007@news.iphouse.com...
> >
> > Perhaps proper slow cornering technique ought to be added to the
> > introductory class. You do have an introductory class for new
> > riders, right? It would reduce the number of crashing newbies.
>
> As a track rider I'm surprised you don't know that most crashes on
> the track are due to the inexperience of riding in a tight pack. I've
> seen riders panic, stop pedaling, touch the rear wheel of the bike in
> front of them. It isn't until one becomes experienced in track riding
> that the newbie's become at ease. When I get back on my roadbike
> after riding the track, everything seems like slow motion.

The crashes I have seen on the velodrome have come from mostly from
grounding a pedal (probably about 5 of those, two of which took me down
when the riders slid down the track into me), a couple from touching
wheels and once from a blowout the cause of which I don't know. All the
pedal strikes occurred on the roll-out before the start of an event.

Oddly enough, the wheel touches all occurred in Cat 1/2/3 races, but
that was just luck of the draw (and smaller fields in those days- there
are twice as many people racing track now than 10 years ago). There
were way more crashes in the Cat 4/5 races. I once did stop pedaling
after a sprint and got a reminder from the bike to not do *that* again.
Fortunately we were all lined up across the track and there wasn't
anyone behind me to get drop-kicked. The official had a little chat
with me after the race, as you might expect.

> Try riding with no hands at 5 mph on the straights of a banked track
> next time you're out there. -tom

I haven't ridden on the velodrome since 1998 or 99 (separated my
shoulder in one of the above-mentioned crashes. Never got back on the
track after that, realizing that at 40 years old I wasn't going to heal
as well as in my youth and that I couldn't afford to lose time from work
over a hobby). I don't even have my track bike any more.

[Tim McNamara]

In article <ffq8f9$4t1$1@news.Stanford.EDU>,
"Tom Nakashima" <tom@slac.stanford.edu> wrote:

> "Tim McNamara" <timmcn@bitstream.net> wrote in message
> news:timmcn-205F17.20571424102007@news.iphouse.com...
> > In article <ffnl8j$3uh$1@news.Stanford.EDU>, "Tom Nakashima"
> > <tom@slac.stanford.edu> wrote:
> >
> >> "Tim McNamara" <timmcn@bitstream.net> wrote in message
> >> news:timmcn-C6BB21.09172624102007@news.iphouse.com...
> >> > In article <ffnhg2$n2$1@news.Stanford.EDU>, "Tom Nakashima"
> >> > <tom@slac.stanford.edu> wrote:
> >> >
> >> >> I was talking with co-worker Timothy Montagne who just got
> >> >> back from the track Nationals in Trexlertown, Pennsylvania. I
> >> >> forget the exact slope on the straights in degrees, but he told
> >> >> me it was so steep that you have to keep a minimum speed of 20
> >> >> mph. or else you would fall over. So I can imagine your speed
> >> >> has to be greater than 20 mph to be able to ride with no hands,
> >> >&