When to Stop Pedalling?

Quoted message said:

I never get over how nice people are in this forum. Do bicycles accelerate human evolution or
something?

Elisa Roselli Paris, France

Funnily enough, the answer to that is "Yes". Bicycles being one of the earliest forms of individual
transport, they permitted marriage between neighbours more distant than had been the norm before.
Hence more genes mixed, hence the species improved. (Define "improved".... ) However, things
*really* got under way with the arrival of steam.

Oh, they really don't have to be steep for _me_ to experience this!! A "faux-plat", as they call
them here, will do amply. As it happens, I'm in Massy, a suburb southwest of the city.

Todd Strong said:

EI'm curious as to where the hills around Paris are steep enough to experience this. Do you work
at Sacre Couer? :-)

Elisa Roselli Paris, France

Tried it and hate it! Have the impression that I'm losing all control of the vehicle and have
nothing to balance on.

So far, my balance isn't up to standing on the pedals (which I guess is what you mean by
"unweighting the saddle"😉.

Actually, the slightest thing will perturb my balance. Looking to the side, trying to ring the bell,
steering, shifting gears, being passed by a car, a sidewalk step, a strong breeze....

I'm agog when I see cyclists yakking away on their mobile phones or pedalling with no hands.

Practise continues.

Elisa Francesca Roselli, Paris, France

Elisa Francesca Roselli said:

Thanks to everyone for their input on my question. I'll try coasting tonight and see how it feels.

Dennis P. Harris said:

but oh, the rush! my favorite downhill run is from the top of white pass into skagway, alaska ---
8 miles from the top of the pass to customs.

Great technique to get those 7 kg of hash past customs. %°>

Quoted message said:

learn how to adjust the brakes as your pads wear. find a bike maintenance book at your local
library or bookstore. join your local bike club. take a class in bike maintenance and buy the few
simple tools you need to do your own tuneups.

Yessir. One thing at a time.

Cheers,

Ellisa Roselli Paris, France

In article <[email hidden]>,
[email hidden] says...

...

Quoted message said:

Practise continues.

That's the attitude!!

....

--
David Kerber An optimist says "Good morning, Lord." While a pessimist says "Good Lord,
it's morning".

Remove the ns_ from the address before e-mailing.

jacques said:

I just tried to order it from Amazon last week. They took my order but later replied that it was
not available anymore.

I ordered it today on British Amazon (amazon.co.uk) which is much more convenient for me than US
bookshops. They seem to have it on a 4-5 day dispatch.

Cheers,

Elisa Roselli Paris, France

Elisa Francesca Roselli said:

fear attacks me very soon - I don't much like speed.

I'm not too big on speeding headfirst down hills either, but these days I ride a recumbent and it is
Much Better :-)

Guy
===
** WARNING ** This posting may contain traces of irony. chapmancentral.comchapmancentral.comOpen ↗ Advance
notice: ADSL service in process of transfer to a new ISP. Obviously there will be a week of downtime
between the engineer removing the BT service and the same engineer connecting the same equipment on
the same line in the same exchange and billing it to the new ISP.

Kirk Gordon said:

Quoted message said:

Quoted message said:

Not at all. Gyroscopic forces give bikes increased stability at higher speeds. When you are
going really slowly, it is rather easy to fall over, at high speeds you have quite a bit of
stability.

Quoted message said:

Quoted message said:

Oh? Could you please explain how that occurs. You may have noticed that roller-blades are more
stable at higher speeds exactly like ice skates. These are not Segways and do not use gyroscopic
forces for stability. With increased speed stability improves from more rapid response to
steering corrections.

Quoted message said:

The wheels on a bicycle ARE gyroscopes, and stabilize the bike EXACTLY the way that any gyro will
stabilize anything it's attached to.

If that is so, how come a Skibob can be ridden just like a bicycle, in fact it is a bicycle with a
front and a read ski runner on a bicycle like frame.

skibob.orgskibob.orgOpen ↗

I can assure you that the Skibob becomes more stable with speed just as a bicycle does.

Quoted message said:

A bicycle is inherently stable in the fore and aft directions, because that's where the wheels
are, and because the center of mass is also between the wheels. A bicycle needs to be protected
from side-to-side tipping; and that protection (when the bike is moving fast enough) comes from
the horizontal axles of the gyro-wheels.

I think you'll have to establish that this as fact. Your claim, for instance, suggests that folding
bicycles with 14" diameter wheels do not become stable until nearly four times the speed of
conventional bicycles with wheels twice the diameter.

Quoted message said:

And, as with all gyroscopes, the faster the wheels rotate, the more stable they become. The Segway
is different only in the fact that it has an ADDITIONAL gyroscope which is always moving at high
speeds. A bicycle's gyros roll on the ground, so gyroscopic stability is directly proportional to
speed of travel. A slow moving bicycle becomes unstable in exactly the way a Segway would if it's
internal gyro were to slow down.

I think you can leave the Segway out of this. It's gyros are heavy and spinning at several thousand
rpm. Bicycles can be ridden at walking speeds where there are no perceptible gyroscopic forces. That
is why bicycles don't ride no-hands at walking speed without a greatly skilled rider.

Quoted message said:

The extent to which a gyroscope will produce stability depends on it's speed of rotation, and also
on its "moment of inertia"...

Quoted message said:

More rapid response to steering at high speeds is not an improvement in stability. It's a mixed
blessing with two kinds of effects. There is, of course, some minimum speed at which a steered
vehicle doesn't operate very well. On boats, which need water flowing across their rudders, this
is called "steerageway." On a car, obviously, you can turn the steering wheel all you want, and
nothing will happen if the car isn't rolling...

Wow! I had no idea so much myth and lore on the dynamics of motion, be that ships or automobiles,
was so adamantly believed in such unrelated mechanisms. From this one could believe that cars will
tip over when standing still, or ships will sink, since you include them in this bizarre
dissertation on gyroscopic stability that goes on and on.

This is a spoof, isn't it?

Jobst Brandt [email hidden] Palo Alto CA

Kirk Gordon said:

Quoted message said:

Quoted message said:

Not at all. Gyroscopic forces give bikes increased stability at higher speeds. When you are
going really slowly, it is rather easy to fall over, at high speeds you have quite a bit of
stability.

Quoted message said:

Quoted message said:

Oh? Could you please explain how that occurs. You may have noticed that roller-blades are more
stable at higher speeds exactly like ice skates. These are not Segways and do not use gyroscopic
forces for stability. With increased speed stability improves from more rapid response to
steering corrections.

Quoted message said:

The wheels on a bicycle ARE gyroscopes, and stabilize the bike EXACTLY the way that any gyro will
stabilize anything it's attached to.

If that is so, how come a Skibob can be ridden just like a bicycle, in fact it is a bicycle with a
front and a read ski runner on a bicycle like frame.

skibob.orgskibob.orgOpen ↗

I can assure you that the Skibob becomes more stable with speed just as a bicycle does.

Quoted message said:

A bicycle is inherently stable in the fore and aft directions, because that's where the wheels
are, and because the center of mass is also between the wheels. A bicycle needs to be protected
from side-to-side tipping; and that protection (when the bike is moving fast enough) comes from
the horizontal axles of the gyro-wheels.

I think you'll have to establish that this as fact. Your claim, for instance, suggests that folding
bicycles with 14" diameter wheels do not become stable until nearly four times the speed of
conventional bicycles with wheels twice the diameter.

Quoted message said:

And, as with all gyroscopes, the faster the wheels rotate, the more stable they become. The Segway
is different only in the fact that it has an ADDITIONAL gyroscope which is always moving at high
speeds. A bicycle's gyros roll on the ground, so gyroscopic stability is directly proportional to
speed of travel. A slow moving bicycle becomes unstable in exactly the way a Segway would if it's
internal gyro were to slow down.

I think you can leave the Segway out of this. It's gyros are heavy and spinning at several thousand
rpm. Bicycles can be ridden at walking speeds where there are no perceptible gyroscopic forces. That
is why bicycles don't ride no-hands at walking speed without a greatly skilled rider.

Quoted message said:

The extent to which a gyroscope will produce stability depends on it's speed of rotation, and also
on its "moment of inertia"...

Quoted message said:

More rapid response to steering at high speeds is not an improvement in stability. It's a mixed
blessing with two kinds of effects. There is, of course, some minimum speed at which a steered
vehicle doesn't operate very well. On boats, which need water flowing across their rudders, this
is called "steerageway." On a car, obviously, you can turn the steering wheel all you want, and
nothing will happen if the car isn't rolling...

Wow! I had no idea so much myth and lore on the dynamics of motion, be that ships or automobiles,
was so adamantly believed in such unrelated mechanisms. From this one could believe that cars will
tip over when standing still, or ships will sink, since you include them in this bizarre
dissertation on gyroscopic stability that goes on and on.

This is a spoof, isn't it?

Jobst Brandt [email hidden] Palo Alto CA

Kirk Gordon said:

Quoted message said:

Quoted message said:

Not at all. Gyroscopic forces give bikes increased stability at higher speeds. When you are
going really slowly, it is rather easy to fall over, at high speeds you have quite a bit of
stability.

Quoted message said:

Quoted message said:

Oh? Could you please explain how that occurs. You may have noticed that roller-blades are more
stable at higher speeds exactly like ice skates. These are not Segways and do not use gyroscopic
forces for stability. With increased speed stability improves from more rapid response to
steering corrections.

Quoted message said:

The wheels on a bicycle ARE gyroscopes, and stabilize the bike EXACTLY the way that any gyro will
stabilize anything it's attached to.

If that is so, how come a Skibob can be ridden just like a bicycle, in fact it is a bicycle with a
front and a read ski runner on a bicycle like frame.

skibob.org.ukindex.htmOpen ↗ skibob.orgskibob.orgOpen ↗

I can assure you that the Skibob becomes more stable with speed just as a bicycle does.

Quoted message said:

A bicycle is inherently stable in the fore and aft directions, because that's where the wheels
are, and because the center of mass is also between the wheels. A bicycle needs to be protected
from side-to-side tipping; and that protection (when the bike is moving fast enough) comes from
the horizontal axles of the gyro-wheels.

I think you'll have to establish that this as fact. Your claim, for instance, suggests that folding
bicycles with 14" diameter wheels do not become stable until nearly four times the speed of
conventional bicycles with wheels twice the diameter.

Quoted message said:

And, as with all gyroscopes, the faster the wheels rotate, the more stable they become. The Segway
is different only in the fact that it has an ADDITIONAL gyroscope which is always moving at high
speeds. A bicycle's gyros roll on the ground, so gyroscopic stability is directly proportional to
speed of travel. A slow moving bicycle becomes unstable in exactly the way a Segway would if it's
internal gyro were to slow down.

I think you can leave the Segway out of this. It's gyros are heavy and spinning at several thousand
rpm. Bicycles can be ridden at walking speeds where there are no perceptible gyroscopic forces. That
is why bicycles don't ride no-hands at walking speed without a greatly skilled rider.

Quoted message said:

The extent to which a gyroscope will produce stability depends on it's speed of rotation, and also
on its "moment of inertia"...

Quoted message said:

More rapid response to steering at high speeds is not an improvement in stability. It's a mixed
blessing with two kinds of effects. There is, of course, some minimum speed at which a steered
vehicle doesn't operate very well. On boats, which need water flowing across their rudders, this
is called "steerageway." On a car, obviously, you can turn the steering wheel all you want, and
nothing will happen if the car isn't rolling...

Wow! I had no idea so much myth and lore on the dynamics of motion, be that ships or automobiles,
was so adamantly believed in such unrelated mechanisms. From this one could believe that cars will
tip over when standing still, or ships will sink, since you include them in this bizarre
dissertation on gyroscopic stability that goes on and on.

This is a spoof, isn't it?

Jobst Brandt [email hidden] Palo Alto CA

In article <[email hidden]>, [email hidden] says...

Quoted message said:

Kirk Gordon said:

Quoted message said:

> Not at all. Gyroscopic forces give bikes increased stability at higher speeds. When you are
> going really slowly, it is rather easy to fall over, at high speeds you have quite a bit of
> stability.

Quoted message said:

Quoted message said:

Oh? Could you please explain how that occurs. You may have noticed that roller-blades are more
stable at higher speeds exactly like ice skates. These are not Segways and do not use
gyroscopic forces for stability. With increased speed stability improves from more rapid
response to steering corrections.

Quoted message said:

The wheels on a bicycle ARE gyroscopes, and stabilize the bike EXACTLY the way that any gyro
will stabilize anything it's attached to.

If that is so, how come a Skibob can be ridden just like a bicycle, in fact it is a bicycle with a
front and a read ski runner on a bicycle like frame.

Because there's more than one way to keep it upright. The gyroscopic effect helps, but is not the
only factor. There are people who can balance a stationary bicycle as well, so steering isn't the
only source of stabilizing influence.

Quoted message said:

skibob.org.ukindex.htmOpen ↗ skibob.orgskibob.orgOpen ↗

I can assure you that the Skibob becomes more stable with speed just as a bicycle does.

So do skis, but a bike at 30 mph is far more stable than skis are at the same speed.

Quoted message said:

Quoted message said:

A bicycle is inherently stable in the fore and aft directions, because that's where the wheels
are, and because the center of mass is also between the wheels. A bicycle needs to be protected
from side-to-side tipping; and that protection (when the bike is moving fast enough) comes from
the horizontal axles of the gyro-wheels.

I think you'll have to establish that this as fact. Your claim, for instance, suggests that
folding bicycles with 14" diameter wheels do not become stable until nearly four times the speed
of conventional bicycles with wheels twice the diameter.

To get the *same amount* of stabilizing effect, yes, but again, that's not the only factor at
work here.

...

Quoted message said:

Quoted message said:

More rapid response to steering at high speeds is not an improvement in stability. It's a mixed
blessing with two kinds of effects. There is, of course, some minimum speed at which a steered
vehicle doesn't operate very well. On boats, which need water flowing across their rudders, this
is called "steerageway." On a car, obviously, you can turn the steering wheel all you want, and
nothing will happen if the car isn't rolling...

Wow! I had no idea so much myth and lore on the dynamics of motion, be that ships or automobiles,
was so adamantly believed in such unrelated mechanisms. From this one could believe that cars will
tip over when standing still, or ships will sink, since you include them in this bizarre
dissertation on gyroscopic stability that goes on and on.

That is not what he was referring to here; he was referring to steering effects and their
relationship to speed, not gyroscopic effects.

--
David Kerber An optimist says "Good morning, Lord." While a pessimist says "Good Lord,
it's morning".

Remove the ns_ from the address before e-mailing.

In article said:

Quoted message said:

Pb? Walther said:

Not at all. Gyroscopic forces give bikes increased stability at higher speeds. When you are going
really slowly, it is rather easy to fall over, at high speeds you have quite a bit of stability.

Oh? Could you please explain how that occurs. You may have noticed that roller-blades are more
stable at higher speeds exactly like ice skates. These are not Segways and do not use gyroscopic
forces for stability. With increased speed stability improves from more rapid response to
steering corrections.

The wheels on a bicycle ARE gyroscopes, and stabilize the bike
EXACTLY the way that any gyro will stabilize anything it's attached to.

David Jones (physicist) constructed a number of experimental bikes while doing some empirical
studies of bicycle stability. One of these had a counter-rotating wheel mounted on the fork. There
was no significant impact on stability. Other factors (fork trail) are much more important.

Originally published in Physics Today in the 70s, IIRC. Fun stuff!

-frank
--

Kirk Gordon said:

The wheels on a bicycle ARE gyroscopes, and stabilize the bike
EXACTLY the way that any gyro will stabilize anything it's attached to.

Indeed. However, the effect is negligible. If it weren't, a bike, once up to speed, would coast
happily without a rider, rather than falling over almost immediately. It doesn't.

Quoted message said:

The extent to which a gyroscope will produce stability depends on it's speed of rotation, and
also on its "moment of inertia". Moment of inertia is what physicists call the combination of a
spinning object's mass and the distance of its mass from the center of rotation. Basically, if
two different size wheels had exactly the same mass, and were both rotating at the same RPM,
the larger wheel would be a more effective gyro. Or, if the two wheels were the same diameter,
and were moving at same RPM, the heavier wheel would be the better gyro. This means that very
light bike wheels need to spin faster than heavy wheels, in order to create the same gyroscopic
stability.

Why don't you calculate the moment of inertia for a typical bike wheel plus its rotational velocity.
See how big the effect really is.

Quoted message said:

High speed, however, makes every little change in steering wheel
direction, from any cause, have a more dramatic effect on the vehicle's
direction of travel. To steer well and stably at high speed requires
smaller, more subtle steering corrections than at low speed. It will

Just like driving a car. Whoop-de-doo.

Quoted message said:

When steering action is considered at both extremes of the speed
range, it becomes clear that very fast isn't any better than very slow;

You haven't actually tried this much, have you? I can balance my bike perfectly well when moving at
about 20 centimeters per second, aka under 1 km/h, as well as at the highest speeds I've ever been
able to reach safely.

Quoted message said:

to sit up for a moment, and take your hands off the handlebar. Riding hands-free is tough to do at
low speeds because there's nothing to keep the front wheel from wandering anywhere it wants to. The
rider must continually shift his/her weight left and right, keeping the center of mass over the
wandering wheels at all times. At higher speeds, however, the front wheel's gyroscopic action
prevents it from wandering around, and keeps it rolling in a nice straight line. In this case, the
rider must NOT shift weight, or the center of mass would move away from the center of the wheel
line, and the front wheel would resist changing direction to correct.

Christ. At high speeds, with hands off, you STILL balance by moving your weight around, but just
like steering corrections *they are very small and subtle*.

Quoted message said:

on a path, or divots in an ice surface. (The wheels on rollerblades are gyroscopes, too; but their
diameters and masses are so small that they'd need to move at insane speeds before the effect could
matter.) There

The same goes for bicycle wheels. Do the math.

Jasper

archer ns_archer1960@ns_hotmail.com said:

Because there's more than one way to keep it upright. The gyroscopic effect helps, but is not the
only factor. There are people who can balance a stationary bicycle as well, so steering isn't the
only source of stabilizing influence.

Yes, they do it by steering. To be more exact, they steer in a particular direction, and then
instead of moving side to side by steering two different ways, they move the bike backwards or
forwards, effectively reversing the effect of the steering from left to right and vice versa.

Jasper

(Todd Strong) said:

I'm curious as to where the hills around Paris are steep enough to experience this. Do you work at
Sacre Couer? :-)

Paris is full of hills. Hell, the whole of France is just one range of hills next to the other.

Jasper "Flatlander" Janssen

In article said:

If that is so, how come a Skibob can be ridden just like a bicycle, in fact it is a bicycle with a
front and a read ski runner on a bicycle like frame.

skibob.org.ukindex.htmOpen ↗ skibob.orgskibob.orgOpen ↗

I can assure you that the Skibob becomes more stable with speed just as a bicycle does.

Hey! I won something like that in a raffle like 25-30 years ago. Much simpler than these- no
suspension, for one thing- and might even have been called a "Skibob." It was a gas, even though we
didn't have hills big enough to really take advantage of it.

In article <[email hidden]>, [email hidden] says...

Quoted message said:

archer ns_archer1960@ns_hotmail.com said:

Because there's more than one way to keep it upright. The gyroscopic effect helps, but is not the
only factor. There are people who can balance a stationary bicycle as well, so steering isn't the
only source of stabilizing influence.

Yes, they do it by steering. To be more exact, they steer in a particular direction, and then
instead of moving side to side by steering two different ways, they move the bike backwards or
forwards, effectively reversing the effect of the steering from left to right and vice versa.

I'm not talking about a track stand;. I've seen people balance an otherwise completely motionless
bike. Sort of like a tight-rope walker standing in one place.

--
Dave Kerber Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

Leave the Engineer to decipher it all!

Bicycles, yes, do have two large gyroscopes on their frames. If these present an inherent stability
at high speeds, why then do people like Mario Cipollini (sp?), currently the fastest man on a bike
at about 50mph, have the ability to tip the bike back and forth easily to augment their pedaling
cadence? A gyroscope the mass and size of a bike wheel, in order to impart any sort of stability at
all on a ~175lb man and bike, needs to be spinning well in excess of any possible speed, regardless
of slope or tailwind. The high-speed stability of a bike comes from its traction. At high rotational
speeds, the majority of a tire's tractive force (actually a frictional force) is involved in merely
keeping the tire rotating. If you were to try to impart any lateral force(as is done by a turning of
the handlebars), its effect would be greatly reduced. The same is true in your car. High speed
cornering requires a much larger turning radius than at low speeds, because you have less
avaliable(unused) traction. So, yes, a bike is more stable at high speeds, but for the same reason a
car has less maneuverability at high speeds.

Quoted message said:

David Jones (physicist) constructed a number of experimental bikes while doing some empirical
studies of bicycle stability. One of these had a counter-rotating wheel mounted on the fork. There
was no significant impact on stability. Other factors (fork trail) are much more important.

Originally published in Physics Today in the 70s, IIRC. Fun stuff!

-frank

Was this what I recall as being an attempt to design an Unrideable Bike? I remember reading of this
a long time ago (the '70s could well be it). I have the impression it was being done in a Yoonie in
NE England. One newspaper drawing I saw showed one version had a t-i-n-y front wheel, trailing from
the fork bottom. Dunno if it ever got off the ground (in a manner of speaking).

Prometheus said:

Leave the Engineer to decipher it all!

Bicycles, yes, do have two large gyroscopes on their frames. If these present an inherent
stability at high speeds, why then do people like Mario Cipollini (sp?), currently the fastest man
on a bike at about 50mph...

Sam Whittingham has gone 81.00 mph (130.36 kph) [1] under his own power on a bicycle.

[1] < ihpva.orghpvarec7.htmlOpen ↗ >

Tom Sherman - Quad Cities USA (Illinois side)