Learning to ride a bicycle

On Tue, 18 Nov 2003 10:56:12 -0000, "Dave Larrington"
wrote:

'ere, who are you calling "Danny"?

[Takes ball, goes home]


Whoops! I abase (stops to check middle vowel) myself before thee.

James

--
"Sorry mate, I didn't see you" is not a satisfactory excuse.

Dave Larrington wrote:
In the Days of my Youth I taught myself to ride a bike with hands
crossed.

I'd like to see you try that on Cosimo ;-)

--
Danny Colyer (the UK company has been laughed out of my reply address)
http://www.speedy5.freeserve.co.uk/danny/
"He who dares not offend cannot be honest." - Thomas Paine

Sue writes:

I have an adult friend who'd like to ride but is deterred by the
learning stage, especially the possibility of falls.

How should he go about learning to ride in a few minutes?

Whooh! Tricky!

Riding a bicycle is all about letting go. When you sit on a bicycle
with your hands on the handlebars it looks as if you steer with your
hands, but (except at very low speeds) you not only don't, you
mustn't. Above a certain speed (which varies according to the geometry
of the bike) the bicycle is dynamically stable if you don't mess with
it too much, and is steered by small and subtle shifts of balance. The
problem is that this is not at all instinctive - at least at first
(for those of us who learned to ride as children, it is so deeply
embedded that it _seems_ instinctive - but it isn't).

Most things you do, the faster you go the trickier it becomes. With
more or less everything you do, the faster you go the more crashing
will hurt. So beginners tend to do things slowly. But riding a bicycle
slowly is really tricky, and, what's worse, it's actually different to
riding a bicycle fast. That's why riding 'no hands' is easy on most
bikes at about twelve mph, but horribly difficult at four.

I think the thing that most beginners do wrong is that they hold the
handlebars too rigidly and try to steer; and that they try to go too
slowly.

I also think that if I was trying to teach an adult beginner to cycle
I'd start on a large smooth area of short grass with sufficient slope
that the bike will roll at about 10mph without pedalling. Then the
learner can learn about balance and steering before they have to
co-ordinate with pedalling action.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; better than your average performing pineapple

On Thu, 20 Nov 2003 15:35:05 GMT, Simon Brooke
wrote:


Riding a bicycle is all about letting go. When you sit on a bicycle
with your hands on the handlebars it looks as if you steer with your
hands, but (except at very low speeds) you not only don't, you
mustn't. Above a certain speed (which varies according to the geometry
of the bike) the bicycle is dynamically stable if you don't mess with
it too much, and is steered by small and subtle shifts of balance.

Wrong. Most steering at higher speeds _is_ done through the 'bars,
just in the opposite direction to what you'd expect. This is known as
counter-steering, and is a well-known phenomenon, particularly amongst
motorcyclists.

There are two effects at work,

1. the steering geometry of the bike causes it to 'fall' in the
opposite direction to that the bars are moved in, and it's inherent
stability will then cause the wheel to move back in the right
direction.
2. The gyroscopic effect, whereby pressure on a revolving object will
always cause it to move in a 90deg plane to that in which the force is
applied. So by pushing forward with one handlebar it will again fall
towards the side that was pushed forwards.

--
Ace (bruce dot rogers at roche dot com)
Ski Club of Great Britain - http://www.skiclub.co.uk
All opinions expressed are personal and in no way represent those of the Ski Club.

On Thu, 20 Nov 2003 17:02:39 +0100, Ace wrote:

There are two effects at work,
[...]
2. The gyroscopic effect, whereby pressure on a revolving object will
always cause it to move in a 90deg plane to that in which the force is
applied. So by pushing forward with one handlebar it will again fall
towards the side that was pushed forwards.

The gyroscopic effect may well play a part when a heavy motorbike wheel is
rotating at high speed but a bicycle wheel at lower rotational speeds is
very different.

Colin
--

On Thu, 20 Nov 2003 16:08:40 -0000, Colin Blackburn
wrote:

On Thu, 20 Nov 2003 17:02:39 +0100, Ace wrote:

There are two effects at work,
[...]
2. The gyroscopic effect, whereby pressure on a revolving object will
always cause it to move in a 90deg plane to that in which the force is
applied. So by pushing forward with one handlebar it will again fall
towards the side that was pushed forwards.

The gyroscopic effect may well play a part when a heavy motorbike wheel is
rotating at high speed but a bicycle wheel at lower rotational speeds is
very different.

I think you'll find that a bicycle's wheel actually makes up a higher
proportion of its total mass than does that of a motorcycle, so the
relative effect at any given speed will be higher.

Granted that it's more significant at higher speeds, but IME speeds
above 5mph are enough to be able to notice the gyro. effect, and
certainly at 10mph or more it's the predominant component of steering
input. Dunno about you, but I very rarely cycle more slowly than that.

--
Ace (bruce dot rogers at roche dot com)
Ski Club of Great Britain - http://www.skiclub.co.uk
All opinions expressed are personal and in no way represent those of the Ski Club.

Colin Blackburn wrote:
The gyroscopic effect may well play a part when a heavy motorbike
wheel is rotating at high speed but a bicycle wheel at lower
rotational speeds is very different.

I know that is the accepted wisdom with bicycles (that gyroscopic forces
are a very minor factor in stability) but I have difficulty in believing
it.

Hold and spin a 26"+ wheel on its own in your hands and try to move and
rotate it about. There is a strong gyroscopic effect even when spun at
lower than normal cycling speed. It must be colossal at 20mph+.

[I don't know what this has to with skiing so I've removed
rec.skiing.resorts.europe from the x-post]

~PB

In article , Ace wrote:

Granted that it's more significant at higher speeds, but IME speeds
above 5mph are enough to be able to notice the gyro. effect, and
certainly at 10mph or more it's the predominant component of steering
input.

No it isn't. A bike with a counter-rotating front wheel to eliminate
the gyro effect has even been built to prove this. rec.bicycles.tech
will probably have more than you want to know about the subject in the
FAQ and past Googleable posts.

On Fri, 21 Nov 2003 13:32:55 -0000, Pete Biggs
wrote:

Colin Blackburn wrote:
The gyroscopic effect may well play a part when a heavy motorbike
wheel is rotating at high speed but a bicycle wheel at lower
rotational speeds is very different.

I know that is the accepted wisdom with bicycles (that gyroscopic forces
are a very minor factor in stability) but I have difficulty in believing
it.

In that case read "The Stability of the Bicycle", David Jones, Physics
Today, 23(4) 1970 pp34-40. He found that a light riderless bicycle was
subject to significat gyroscopic effects but a ridden bicycle was not. A
bicycle with a counter-rotating wheel could be balanced and steered just
as easily. The gyroscopic forces are there but with the weight of the
rider they are no significant.

Hold and spin a 26"+ wheel on its own in your hands and try to move and
rotate it about. There is a strong gyroscopic effect even when spun at
lower than normal cycling speed. It must be colossal at 20mph+.

Yes, but that is just a wheel, it isn't a wheel with a person attched to
it who isn't rotating.

[I don't know what this has to with skiing so I've removed
rec.skiing.resorts.europe from the x-post]

I think that's where the original thread came from but there is a slight
relevance in that ski bikes are balanced in very much the same way but
they have no rotating parts and so no gyroscopic forces.

Colin
--

Alan Braggins wrote:

In article , Ace wrote:

Granted that it's more significant at higher speeds, but IME speeds
above 5mph are enough to be able to notice the gyro. effect, and
certainly at 10mph or more it's the predominant component of steering
input.


No it isn't. A bike with a counter-rotating front wheel to eliminate
the gyro effect has even been built to prove this. rec.bicycles.tech
will probably have more than you want to know about the subject in the
FAQ and past Googleable posts.



Whatever. It's all off-topic as far as rec.skiing.resorts.europe is
concerned. Could you confine this thread to uk.rec.cycling from now on
please, unless any of this has anything to do with skiing?

I know the original x-post was from r.s.r.e, I don't think the x-posting
serves any purpose anymore.