Mobile Speed Cameras......Again

[John Brown]

If you have the chance to look at a cyclists actual track on the ground (wet/dry roads, muddy tracks etc) you will see that all cyclists weave very perceptibly. Faster they go the longer the swing from side to side.
Cycling (and motor biking, skiing or skating) is series of controlled falls from one side to the other. It's controlled by turning into the fall which throws you the other way by centripetal force. So if you are so close to the kerb that you can't turn towards it you will fall off. Except of course were the weaving path at it's outermost point just reaches the kerb .
If you tried to ride a bike with the steering locked it's virtually impossible and is more like tight rope walking where you balance with the aid of a long pole or your arms stretched out.

Jacob

If you want to turn right on your bike which way do you turn the bars?

See if you can work it out.

Pete

That's not really a thing that anyone could be expected to work out, as it's totally counter-intuitive.

Work this out instead:
If I take a wooden sphere, and drill a hole symetrically from one side through to the other, such that the centre of the drill bit passes exactly through the centre of the sphere, and exits fully at the far side, what is the volume of wood remaining in what was the sphere?




Then tell me, hand on heart, that you didn't google it.

 

[Jacob]

If you have the chance to look at a cyclists actual track on the ground (wet/dry roads, muddy tracks etc) you will see that all cyclists weave very perceptibly. Faster they go the longer the swing from side to side.
Cycling (and motor biking, skiing or skating) is series of controlled falls from one side to the other. It's controlled by turning into the fall which throws you the other way by centripetal force. So if you are so close to the kerb that you can't turn towards it you will fall off. Except of course were the weaving path at it's outermost point just reaches the kerb .
If you tried to ride a bike with the steering locked it's virtually impossible and is more like tight rope walking where you balance with the aid of a long pole or your arms stretched out.

Jacob

If you want to turn right on your bike which way do you turn the bars?

See if you can work it out.

Pete

If you turn the bars to the right you will fall to the left, unless you also lean to the right. So it's a controlled fall to the right.
In fact, if the geometry of your bike allows it, you can steer by leaning alone.

 

[Racers]

So a bike is kept upright by the two gyroscopes formed by the wheels that's why counter steering works, in one Yamaha racing bike the engine spun backwards so you could change direction faster.

Pete

 

[Jacob]

I'm not sure that gyroscopes have anything to do with it on push bikes. Maybe it would with a motorbike and a big mass of heavy engine going round fast, but you can steer a motorbike downhill in neutral with the engine off, and skiers/skaters don't have moving parts at all.

 

[mseries]

So a bike is kept upright by the two gyroscopes formed by the wheels that's why counter steering works, in one Yamaha racing bike the engine spun backwards so you could change direction faster.

Pete

studies have demonstrated that the gyroscopic forces are not responsible for making a bike stay upright.

 

[RogerS]

We all know that it is the Jedi 'force' that keeps bikes upright.

 

[Racers]

Take your bike wheel out hold it by the axle and get some one to spin it and feel the force needed to turn it.

http://www.youtube.com/watch?v=vk7Xzp5Cts8

http://www.youtube.com/watch?v=yNbOh0N3BSs

Pete

 

[Jacob]

I know! But it's not clear to me what it contributes to steering, if anything at all.

PS I looked it up. The answer is next to nothing. http://www2.eng.cam.ac.uk/~hemh/gyrobike.htm

 

[JustBen]

I can't quite remember what sport it is but there is a bike sport where the steering is almost non existent and the turning circle from steering is huge.
I'm sure it's some form of oval racing though.

But is does show that steering plays little part in keeping a moving bike on its wheels and going straight.

How many of you have cycled without hands on the bars and the bike stayed up and cornered?
How many of you have seen bikes lose their riders and continue in a straight line and only fall when the momentum stops?

The only people i see steering a bicycle on the roads are those who are moving too slow (mainly drunks and old people)

 

[Finial]

All I am really after is an agreement that just as there are bad inconsiderate motorists, so to are there bad and inconsiderate cyclists.

I'll give you that, but with some provisos. Firstly, don't know about you, but I've never been hit, threatened or even inconvenienced by someone on a bike, whereas I've been hit more than once by a driver and endure horn blowing and abuse from road hogs quite often. Secondly that bike riders, being much more vulnerable, are generally more safety-conscious than drivers - so much so that most have been driven off the roads by fear of motor traffic. Thirdly, the number of drivers injured in collisions with bikes is as small as you would expect. The war between riders and drivers is very unequal and some people are much too ready to blame the victims.

 

[John Brown]

I know! But it's not clear to me what it contributes to steering, if anything at all.

PS I looked it up. The answer is next to nothing. http://www2.eng.cam.ac.uk/~hemh/gyrobike.htm

That's very interesting. I have to admit that, up until today, it would never have occurred to me that gyroscopes spinning in opposite directions would cancel out.

 

[Jacob]

......
But is does show that steering plays little part in keeping a moving bike on its wheels and going straight.

It's absolutely essential. If you can't steer the bike will fall over, sooner or later, depending on the geometry

How many of you have cycled without hands on the bars and the bike stayed up and cornered?

Depends on geometry - so my road bike can be steered (just about), with hands off, on a smooth road with no bends, not very far, but my touring bike is much more difficult.

How many of you have seen bikes lose their riders and continue in a straight line and only fall when the momentum stops?

Momentum and steering geometry helps, but never in a straight line - it'll do an ever decreasing circle until it falls over or hits something. It could veer off if it hits a bump, and circle the other way

The only people i see steering a bicycle on the roads are those who are moving too slow (mainly drunks and old people)

What, everybody else has their hands off? :lol: Not around here they don't!

 

[Jacob]

I know! But it's not clear to me what it contributes to steering, if anything at all.

PS I looked it up. The answer is next to nothing. http://www2.eng.cam.ac.uk/~hemh/gyrobike.htm

That's very interesting. I have to admit that, up until today, it would never have occurred to me that gyroscopes spinning in opposite directions would cancel out.

Nor me. Presumably front and back wheels react differently too; one is being turned by the rider, the other being tilted by the leaning frame. Do they cancel each other out? Gyroscopes are a bit of a mystery!

 

[mseries]

found this on the BBC http://www.bbc.co.uk/news/magazine-13040607

Pedestrian casualties 2001-09

Killed by cycles: 18
Seriously injured by cycles: 434
Killed by cars: 3,495
Seriously injured by cars: 46,245

Figures apply to Great Britain. Source: Department for Transport

Those figures aree meaningless. What you are ignoring is that the central premise of the Times article/research was that cyclists travel less miles in total than motorists. If you then look at the number of accidents caused by cyclists compared to motorists per miles travelled then proportionately cyclists cause just as much injury.

All I am really after is an agreement that just as there are bad inconsiderate motorists, so to are there bad and inconsiderate cyclists.

Of course I agree that there are bad and inconsiderate cyclists,it really pisses me off that there are because it's those who get us all a bad name and cause other road users to demand various sanctions for riders.

Those figures are not meaningless,if they are true and I suspect they are it means that cars killed many more pedestrians than cycles did in the same time frame. The Times interpretation of the data to me says the same thing because I know that cycles generally travel fewer miles than cars and are less common so hence less likely to kill. The data that the BBC page showed isn't per mile, it's a body count, that many people were killed by each mode of transport it's real, to me it puts it into perspective, you are nearly 200 times more likely to be killed on the pavement by a car than you are by a bicycle.

 

[JustBen]

I'm not sure how you cycle Jacob, but I was able to (and presumably still can) cycle for many miles without putting my hands on the bars. The forward momentum keeps the bike on track and only requires slight leaning to change direction.

For some reason, the picture in my head of you cycling, Jacob, is that of Granville from Open All Hours.
Ha ha. I don't know what made me think of it and I'm sorry if it upsets you.

 

[mseries]

I can't quite remember what sport it is but there is a bike sport where the steering is almost non existent and the turning circle from steering is huge.
I'm sure it's some form of oval racing though.

But is does show that steering plays little part in keeping a moving bike on its wheels and going straight.

How many of you have cycled without hands on the bars and the bike stayed up and cornered?
How many of you have seen bikes lose their riders and continue in a straight line and only fall when the momentum stops?

The only people i see steering a bicycle on the roads are those who are moving too slow (mainly drunks and old people)

You don't really steer round the bends on the velodrome. Just pedal and the banked ends cause you go round.

 

[MMUK]

I can't quite remember what sport it is but there is a bike sport where the steering is almost non existent and the turning circle from steering is huge.
I'm sure it's some form of oval racing though.

But is does show that steering plays little part in keeping a moving bike on its wheels and going straight.

How many of you have cycled without hands on the bars and the bike stayed up and cornered?
How many of you have seen bikes lose their riders and continue in a straight line and only fall when the momentum stops?

The only people i see steering a bicycle on the roads are those who are moving too slow (mainly drunks and old people)

You don't really steer round the bends on the velodrome. Just pedal and the banked ends cause you go round.

Not quite. You counter-steer just like on a motorbike.

 

[Jacob]

I'm not sure how you cycle Jacob, but I was able to (and presumably still can) cycle for many miles without putting my hands on the bars. The forward momentum keeps the bike on track and only requires slight leaning to change direction.

For some reason, the picture in my head of you cycling, Jacob, is that of Granville from Open All Hours.
Ha ha. I don't know what made me think of it and I'm sorry if it upsets you.

I see you as a cherubic innocent on a trike, saying "look no hands" just before falling into a ditch. :lol:
You couldn't do mile after mile no hands - a few hundred yards at best.

 

[JustBen]

A few hundred yards?....

http://youtu.be/vB4P672Y9BM

 

[RogerS]

......, but I've never been hit, threatened or even inconvenienced by someone on a bike, .....

I have as a pedestrian walking on the pavement in London!