Learning to ride a bicycle

On Fri, 21 Nov 2003 15:39:11 +0000, Steve Haigh
wrote:

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.

Purpose? Jeeze, this is a low-enough volume group that a bit of chat
hardly does any harm, now does it? Now if it had been x-posted to ukrm
that might have been different...\
--
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 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.

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+.


Hi Pete

I appreciate what you are saying about the gyroscopic effect on a
tilting wheel but one can cycle for a lifetime without needing to
counter steer.

My bikes each have these two devices, one at the back of the bike and
one towards the front, which are used to slow down the cycle. They're
most useful when approaching corners ;-)

James

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

Ace writes:

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.

We had this discussion on rec.bicycles.tech recently, you should look
it up. I tried some experiments and filmed them; I'll post a URL if
you're interested. The gyroscopic effects certainly exist, but they're
very weak compared to the gravitational effects. Bicycles
fundamentally steer by lean (as you yourself point out); the
gyroscopic effect at best helps to damp steering movements. Obviously
the gyroscopic effects increase with speed, but they don't become
dominant at speeds a human being can cycle at. There's an
interesting paper by a guy called David Jones called 'The Stability of
the Bicycle' which you might read; among other things he built a
bicycle with a counter-rotating gyroscope to cancel out any gyroscopic
effects from the front wheel. It rode perfectly well.

I have to say that some so-called experts are so wedded to the
gyroscopic theory in the face of overwhelming evidence that if you
show them actual film of an actual experiment they'll still deny the
evidence of their own eyes, but that's their problem.

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

;; I'd rather live in sybar-space

On Fri, 21 Nov 2003 22:05:17 GMT, Simon Brooke
wrote:

Ace writes:

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

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

We had this discussion on rec.bicycles.tech recently, you should look
it up.

I will do so. Been away from there for far too long anyway.

I tried some experiments and filmed them; I'll post a URL if
you're interested.

Please.

I have to say that some so-called experts are so wedded to the
gyroscopic theory in the face of overwhelming evidence that if you
show them actual film of an actual experiment they'll still deny the
evidence of their own eyes, but that's their problem.

G Surely not?

--
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.

In article , Steve Haigh wrote:
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?

(Someone did point out that ski bikes demonstrate the same point.)


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

Followups-To header now set.

Ace writes:

On Fri, 21 Nov 2003 22:05:17 GMT, Simon Brooke
wrote:

Ace writes:

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

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

We had this discussion on rec.bicycles.tech recently, you should look
it up.

I will do so. Been away from there for far too long anyway.

I tried some experiments and filmed them; I'll post a URL if
you're interested.

Please.

OK, web hosting kindly provided by Carl Fogel of that group

URL: http://home.comcast.net/~carlfogel/d...lt_or_gyro.mov
URL: http://home.comcast.net/~carlfogel/d...d/PA121300.mov

The bike has been suspended so that the head tube is initially
vertical. In the second movie the handlebars have been removed so as
to prevent their weight influencing the result (a criticism that was
made of the first movie).

That's the 25.5" frame of recent controversy, by the way.

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

;; I'd rather live in sybar-space