Hey there.... need some help!

[Janie]

i'm only a girlie so i know nothing...........but it sounds to me as if you put it into too lower gear and thats why the back wheel locked up.......that will of stood ya bike up........hence the reason ya didn't make it round the corner..........
ya need to have more faith in ya bike,
as my old feller always tells me "if in doubt gas it out" and lean over more....... so if u do fall off the bike will slide away from you....
anyway what do i know i'm only a girlie.........

 

[Shep]

A first gear corner....that's bloody tight.

Your stalling problem may not be a 'fault' with the bike, per-se.

Try giving the bike a handfull of rev's (give the throttle a good old blip) on the down change - if nothing else it makes it pop and bang nicely on the overrun - on the approach to the corner. That will settle the bike and match wheel to engine speed, nicely, for the bend.

You will then probably get around it in second (or higher), carrying more rev's and with more drive. In effect the increased rev's (you won't bust the engine, that's for sure) will mirror the effect of a faster idle. May well cure the stalling problem. It's worth a go and costs nothing to try.

Have a watch of the onboard shots of riders at the TT. Watch the rev counter, hear the gear changes and the rapid throttle blips of those bikes without slipper clutches. You can see very quickly that high rev's and drive are king.

In passing, film and pictures of Moto GP riders also help to prove the, 'Go where you look', countersteering and the 'Once the bike is turned, the bars do nothing' theory and rules.

Colin Edwards, with his long neck, shows this really well. The bike and front wheel are pointing one way, his head and neck are straining to look the other way, staring hard - as far ahead as possible - at where he wants to go (he knows the bike will definitely follow) whilst the front wheel is often off the ground (so it cannot be steering).

The first gear corner, in my case is on a single track road with high hedges and a right angle bend, low approach speed is due to the fact I don't want to die just yet

Yes, I can ride around the 'fault' but that only hides the fact that the fault is there, you can blip all you like until the engine stalls, then your fekked

Shep

 

[Rushy]

The nmachine is light at the back with no pillion / luggage and slowing down all the weight is on the front.
mainly happens on wet /damp roads, had a couple of ,good ones whilst out round the Alps at garmish on the BMW ride out (race) gave them a bigger fright than me I think, so whatch out in future we've all don it thtas how you learn.
dave gs.

Aint that the truth .

Had the bike about 3 mths, usual commute to work ,cold morning, started bike with lights and grips on, set off , usual problem of the ABS light flashin' cos of the low oomph from the battery when I started her.

Now most people on here know that all u do is ride for a mile or so , stop , turn bike off and start her up and you are good to go. ABS kick in.

But I was late for work so after a mile at about 15-20mph in 3rd I shut the throttle, pulled the clutch in , turned the ignition off and back on and ................you guessed it, I released the clutch quite quickly in an attempt tu bump start it..........BANG ..IMMEDIATE rear wheel lock up, back end came round really quick even though I was travelling straight. Gave me a Managed to pull the clutch in and save it. Never did that again

 

[Nate]

A first gear corner....that's bloody tight.
In passing, film and pictures of Moto GP riders also help to prove the, 'Go where you look', countersteering and the 'Once the bike is turned, the bars do nothing' theory and rules.

Colin Edwards, with his long neck, shows this really well. The bike and front wheel are pointing one way, his head and neck are straining to look the other way, staring hard - as far ahead as possible - at where he wants to go (he knows the bike will definitely follow) whilst the front wheel is often off the ground (so it cannot be steering).

My understanding of bike steering is this...

Countersteering only works over a certain speed and is due to using the centrapedal force (yes i know it doesn't exist) to alter the lean angle of the bike, thus changing the circumference of the tyres on the road which is the bit that actually gets the bike moving on the radius...

Under the speed that countersteering works, then you have to rely on moving the front wheel to change direction...

Wapping, what you said seems to be different to this... Am i wrong?

 

[Wapping]

My understanding of bike steering is this...

Countersteering only works over a certain speed and is due to using the centrapedal force (yes i know it doesn't exist) to alter the lean angle of the bike, thus changing the circumference of the tyres on the road which is the bit that actually gets the bike moving on the radius...

Under the speed that countersteering works, then you have to rely on moving the front wheel to change direction...

Wapping, what you said seems to be different to this... Am i wrong?

The countersteering effect works at all speeds, the California Race School machine (basically a motorbike held in a frame with outriggers) proves this. It is simply more obviuos above, say, five miles an hour. You can test this in a nice large car park. The same machine proves that simply leaning a bike does nothing, either. You can lean it as hard as you like and nothing happens, the bike goes straight ahead. Again, it's possible to prove this in a large empty car park.

You can also test it all out by riding around with just your right hand on the bars. Turn left and right by simply pulling or pushing in the opposite direction. Empty three lane motorways are excellent, as you zip from lane to lane. I wouldn't suggest you try this on the M1 in rush hour or with plod on your tail, though.

Everyone countersteers, at all speeds, most often without realising it.

As you turn your head to look around the bend (say left) your right hand pulls right, initiating the turn left. The problem comes when the rider then tries to push the right hand bar left, making the bike want to go right, ie. in the opposite direction to the bend. The end result is the classic threepenny bit cornering. Left, straight, left a bit more, straight, left a bit more….

The rider is simply fighting the bike and physics. The result is the rider often grips the bars harder, making the problem worse, not better. A sharp jab of the bars in the opposite (counter intuitive) direction, then simply relaxing, will get the bike around in one smooth curve. The deathgrip is always tricky. I was taught, by a very patient instructor, to imagine I was holding a full pint of beer in a smooth glass...that worked for me.

Watch old film of Freddy Spencer and the rest of the Yanks in the Easter Trans-Atlantic races, USA - V - Europe, that we used to enjoy. They were riding the big muscle Hondas and Kwackas, with the raised bars. The riders countersteered the bikes so hard they bent the handlebars.

I you can, get a copy of Keith Codes’, ‘A twist of the wrist’ book. It’s all explained. Better still, the California Race School is excellent, if pricey.

 

[Wapping]

Under the speed that countersteering works, then you have to rely on moving the front wheel to change direction...

Wapping, what you said seems to be different to this... Am i wrong?

Just Googled countersteering.

Here's as good an explanation as any that I have read:

http://en.wikipedia.org/wiki/Countersteering

 

[andyclift]

The first gear corner, in my case is on a single track road with high hedges and a right angle bend, low approach speed is due to the fact I don't want to die just yet

I can't ever remember using first gear for a corner - even two up over Stelvio Pass hairpins - but even changing down to second gives massive engine braking if the revs aren't matched.

Re stalling, I had it happen once as I went around a roundabout, probably in second. Got some honking from the car behind but no sign of any lock up. Dealer could not find a reason, nothing in the fault log, and it hasn't happened in the last 15,000 miles.

As an aside, shortly after passing her test and not used to her 650 BMW, my wife went into a bend a little fast, panicked, grabbed the brakes, bike stood up and straight off the road, fortunately without injury apart from my brown trousers (I was following). She claimed she did nothing - but I saw the brake light come on!!

You can lean it as hard as you like and nothing happens, the bike goes straight ahead.

If this is the case I would like to know the explanation of why I can take both hands of the bars and steer the bike round a bend by leaning to the side.

 

[Nate]

yes ok, countersteering explained... which is what I thought...

But, what makes the bike go round a corner.... Al wikepedia explained is how to countersteer (i.e. push pull on bars ya ya ya)

 

[Wapping]

If this is the case I would like to know the explanation of why I can take both hands of the bars and steer the bike round a bend by leaning to the side.

Not trying to be clever, but I don't think you can, at least not very well. Not by taking both hands off the bars. You may, depending on your speed, carve a very wide circle (not great for the average bend) as the bike slows and starts to fall over. It is then acting as the pendulum described in the Wikepedia article.

I can only speak from experience of the California Race School and Andy Ibbot (no slouch on a bike when he was racing). Their bike is set up and you get on, the throttle is fixed (so it goes along) and they tell you to take your hands off the bars and steer it by leaning. The bike cannot fall over as outriders catch it but you can lean it a long way. The simple fact is, it went straight ahead, for all of us on the course. It was a big eye opener. They then went on to explain why the bike can't steer by simply leaning and the inputs you need to make to make it steer.

You could try it yourself in a big car park. Run a rubber band around the inside of the twist grip so you can open and hold the throttle open enough to get going along at a reasonable speed, Take your hands off the bars and lean....I suggest a big car park....see what happens. Then take the rubber band off, so that the throttle shuts when you take your hands off, now lean, as the bike slows....get ready for the turn and for the ground.

What you can do, or at least think you can do, is have both hands on the bars even gently, lean, say, left and the bike move left. What is happening is that you lean to the left and, due to the shape of your shoulders, chest and arms, and the leverage between them and the bars, your end up pulling back on the right hand bar, even gently....we all now what happens then....the bike moves left. You can probably get the feeling, sitting on a kitchen chair (this is getting very sad), arms out to imaginary bars and lean, no cheating.

Once the bike is in the turn, leant over, then you can, quite happily take your hands off the bars and the bike will continue around the curve. It needs no more steering input from you. On trackdays, if things get a bit ragged in the bend, the bike sorts itself out very well and quickly, by simply relaxing the grip on the bars.

 

[Deleted account 210609001]

Fairy magic.

My understanding is that counter steering is how you get the bike to change the lean angle one way or another. Once leant over, you steer into the corner the orthodox way, i.e. turn the bars left a bit to keep going round the left hand corner.

The corner-turning effect of minimal handlebar turning is exaggerated. (The steeper the steering angle, the more multiplied the effect is.) You can demonstrate this really easily with a pushbike. Keep the bike vertical and turn the handlebars a set amount - say 20 degrees - then push it round in a circle. Measure the turning circle. Now, keep the handlebars turned the same amount but lean the bike into the corner a bit; it will turn in a much tighter circle. Lean it even more and you will soon notice the wheel trying to tuck itself under the bike. Lean a little further still and you won't be able to continue to push.

It is this force - the wheel wanting to steer into the corner - that means you have to push the inside bar forward to hold a bike into the corner. You are NOT countersteering in the true sense, as the front wheel is still pointing in the direction you are turning. But you get the impression of trying to steer in the opposite direction.

If you put no pressure on the bars, the front wheel will generally turn itself at a sharper angle that the corner requires. This will bring the bike more upright and if left unchecked will lead the bike to go straight on. Different steering geometry will affect the level of this. If you have a steeper steering angle, the bike will (all else being equal) need more "holding down" in the corner.

You can offset this effect to varying degrees by having different sized wheels or more steering offset to affect the castor effect and increase the trail. This gave rise to leading axle forks, trailing axle forks, 16 inch front wheels, 18 inch front wheels.


Anyway, I too have been massively surprised at the engine braking effect of a big twin, once when (as described above) I switched off the ignition to reset the power feed to my sat nav. Usually I left the bike in gear so the engine never stopped, but once I did it with the clutch in and just could not get the engine turning in first second or third gears. And I have also "locked" the rear wheel by dumping the clutch on the way into a corner without any blipping. Very scary when you're not used to it.

 

[Wapping]

Fairy magic.

My understanding is that counter steering is how you get the bike to change the lean angle one way or another. Once leant over, you steer into the corner the orthodox way, i.e. turn the bars left a bit to keep going round the left hand corner.

Once you are in the bend, leant over, the geometry of the bike pushes the front wheel around the bend, even though the very large gyroscope of the front wheel is trying its damnest to run upright.

If, in the bend, leant over, you took your hands off the bars, on a constant throttle, the bike would continue the same curve, going around in a big circle, until it ran out of petrol.

You can see what happens in GP races when riders are spat off in a corner. The throttle closes, drive reduces / stops, the bike stands up and carries on, on its own, straight ahead. Similarly, on an open throttle, the bike is leaned over, power pouring through the rear wheel, the front wheel is off the ground (it can't be steering, can it) and the bike is still cornering.

If, in say a left hand bend, leant over, you pushed on the right hand bar, the bike will straighten, reducing your lean angle.

If, in say a left hand bend, leant over, you pulled on the right hand bar, the bike will turn sharper into the bend, increasing your lean angle.

Chapter 9 of Keith Code's excellent book, describes it exactly.

Here is a pretty good picture, that shows it all. Look at the front wheel, look at where the Texas Tornado is looking and what his arms must be doing. He has dropped his right shoulder into the bend. This pushes the bar right hand out (away from the bend) you can see where the wheel is pointing. His arms are nicely bent (loose, not tense) and the grip on the bars must be relaxed.

And now the other way around. You can see, the left shoulder dropped into the corner, the left arm pushed forward, the wheel is pointing right (the black V of the SP's air intake in the nose of the fairing emphasises the centre line) and the bike cornering left.

 

[camel_landy]

Nice pics...

One of the main things I think of with the counter steer is that it effectively shortens the wheelbase, therefore making for a tighter turn.

M

 

[chasr]

Once you are in the bend, leant over, the geometry of the bike pushes the front wheel around the bend, even though the very large gyroscope of the front wheel is trying its damnest to run upright.

You are assuming the Colin doesn't continue to apply the countersteering force, which he does.

One aspect not mentioned yet, is the rake (or trail, can't remember which is which) at the front. The contact patch from the front wheel is behind the extended fork-line. The drag from this has no gyroscopic component, but continues to provide lateral stability - which is why we can ride with no hands (except for one of my bikes which is bent).

 

[Tramperman]

Oh dear!

If you are new to BMs then I would suggest the following. If you are not dead positive with your gear change you may hit a false neutral, immediatly
go for the clutch, as you will not know whether to change up or down. Because you will not know what gears you are between.
DO NOT release that clutch lever. Shut off on the throttle and go round without power, it not a problem. If you did release the clutch you may find that you are in a lower (too low) gear,which may cause the rear wheel to lock up. With disasterous consequences. Once clear of the bend and on the straight, change UP the box. hen tell yourself not to rush these slow ole gears

A bit late know I hear you say!

Ive been riding GS's since 2000 and Ive never heard of a fault with the bike.

 

[Wapping]

You are assuming the Colin doesn't continue to apply the countersteering force, which he does.

One aspect not mentioned yet, is the rake (or trail, can't remember which is which) at the front. The contact patch from the front wheel is behind the extended fork-line. The drag from this has no gyroscopic component, but continues to provide lateral stability - which is why we can ride with no hands (except for one of my bikes which is bent).

...Much of the additional movement or pressure on the bars is necessary only to keep the bike in balance, only because the track is either not smooth or cambered. Keith Code's book explains it all.

....Of course I could have gone on to point out that he is also drifting the bike sideways, both tyres sliding right to left (or left to right) in relation to his line of travel, thereby allowing him to turn in later and widening the corner, enabling him to straighten the bike slightly earlier...but I thought enough was enough....

 

[Wapping]

DO NOT release that clutch lever. Shut off on the throttle and go round without power, it not a problem.

That is the first time I have ever seen anyone recomend going around any corner, on any motorcycle, with the clutch pulled, on a closed throttle....

In other words, no power to the rear wheel at all and no drive....the bike is simply rolling.....

Please show us one clear and concise example where anyone else has suggested that this is a good idea.....

 

[spock]

That is the first time I have ever seen anyone recomend going around any corner, on any motorcycle, with the clutch pulled, on a closed throttle....

In other words, no power to the rear wheel at all and no drive....the bike is simply rolling.....

Please show us one clear and concise example where anyone else has suggested that this is a good idea.....

To true Wapp,hell if I would want to try this.
"If" and when I have had the old gal find a false neutral,I will always shift up,

 

[Doofus]

The countersteering effect works at all speeds, the California Race School machine (basically a motorbike held in a frame with outriggers) proves this. It is simply more obviuos above, say, five miles an hour. You can test this in a nice large car park. The same machine proves that simply leaning a bike does nothing, either. You can lean it as hard as you like and nothing happens, the bike goes straight ahead. Again, it's possible to prove this in a large empty car park.

You can also test it all out by riding around with just your right hand on the bars. Turn left and right by simply pulling or pushing in the opposite direction. Empty three lane motorways are excellent, as you zip from lane to lane. I wouldn't suggest you try this on the M1 in rush hour or with plod on your tail, though.

Everyone countersteers, at all speeds, most often without realising it.

As you turn your head to look around the bend (say left) your right hand pulls right, initiating the turn left. The problem comes when the rider then tries to push the right hand bar left, making the bike want to go right, ie. in the opposite direction to the bend. The end result is the classic threepenny bit cornering. Left, straight, left a bit more, straight, left a bit more….

Hi

If I may offer my understanding, I am not sure I agree with some of this. (To all you physicist out there I know I have glossed over some details!)

We do steer differently at different speeds. This is becaue to steer we need to apply a sideways force to the bike, and the way we apply the force depends on our speed.

At low speeds we steer by pointing the front wheel in the direction we want to go. The force required to turn the bike in this case is basically a friction force associated with the front wheel (combined with the fact the front wheel is contrained to roll only about its axis). We do not countersteer at low speeds, we point the front wheel in the direction we want to go (we must all remember this from the doing the U-turn on our driving test no matter what the California Race School machine does!)

At high speed we apply the force in a different way. We lean the bike in the direction we want to go so that the centre of mass of the bike PLUS rider is no longer over the wheels. The turning force in this case then basically comes from the bike PLUS rider wanting to topple over, thankfully the various laws of physics conspire such that we do not topple over, but we go in a gentle curve with the centrifugal force stopping us from low-siding (i.e. balancing the toppling force).

It is true that we cannot steer by simply shifting in our seat to make the bike lean, this is because the bike will then simply lean one way while we hang off the other way. The centre of mass of bike PLUS rider in this case remains over the wheels and there is no steering (because no toppling-over force).

To make the bike PLUS rider lean, the rider needs to push against something. What we push against is the rotational inertia of the front wheel. There is a large horizontal sideways angular momentum vector running through the front wheel axis due to its high speed of rotation. If we try and turn the wheel about a vertical axis (by turning the handlebars), there is a kind of reaction force applied to the bike PLUS rider about a forward horizontal axis. This reaction force cause the bike to lean (this is a Corriolis-like effect).

The laws of physics are such that when going forwards, rotating the handlebars clockwise (viewed from above) causes the bike PLUS rider to lean to the left (viewed from the rear). You can see this intuitively if you think of yourself going at 90mph and suddenly yanking the right hand handlebar towards you - you are going to get thrown off to the left. Getting the lean right is all about making sure we are thrown to the left by only a small amount. Thankfully, the human motor faculties appear to allow us to do this without really thinking about it (and in many cases without even noticing we're doing it).

Only a small turn of the handebars is required to get enough reaction force to lean the bike enough to make the turn, but nontheless the front wheel does indeed point the wrong way. The toppling force turning us to the left overcomes the friction force from the front wheel pointing to the right and scrubs the tyre - this is probably the main reason front tyres wear out.

When we want to stop leaning, we turn the handlebars back so the reaction force brings us up straight.

To summaris, below a threshold speed the front tyre's friction effect domintates and we steer "normally". Above the threshold speed (i.e. primarily when there is enough angular momentum in the wheels) the Coriollis-like effect dominates and we countersteer. What a lot of people probably don't realise, is that at the threshold speed it is difficult to steer at all as the two effects balance! This is about the speed I tend to be going when things suddenly appear in the road which I want to avoid.

Well that's my understanding at least.

Darren

 

[Wapping]

Hi

If I may offer my understanding, I am not sure I agree with some of this. (To all you physicist out there I know I have glossed over some details!)

Well that's my understanding at least.

Darren

The California School bike was set up to show that simply leaning on a moving bike did not result in the bike turning, nothing more.

It also helped to show, quite safely, that sharp turns of the bars, resulted in sharp turns of the bike in the opposite direction, classic countersteering.

Quite neat:

<object width="425" height="355"><param name="movie" value="http://www.youtube.com/v/3nRUeEkS644&rel=1"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/3nRUeEkS644&rel=1" type="application/x-shockwave-flash" wmode="transparent" width="425" height="355"></embed></object>

<object width="425" height="355"><param name="movie" value="http://www.youtube.com/v/C848R9xWrjc&rel=1"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/C848R9xWrjc&rel=1" type="application/x-shockwave-flash" wmode="transparent" width="425" height="355"></embed></object>

 

[Nate]

My understanding of bike steering is this...

Under the speed that countersteering works, then you have to rely on moving the front wheel to change direction...

Wapping, what you said seems to be different to this... Am i wrong?

yes ok, countersteering explained... which is what I thought...

But, what makes the bike go round a corner.... Al wikepedia explained is how to countersteer (i.e. push pull on bars ya ya ya)

OK so I probably didnt phrase my question well... But what makes it go round a corner...? I understand and use countersteering (passive and active) when i'm on my bike.... you have to, whether you know it or not.... But... What makes the bike corner (as opposed to what initiates a turn)...

So far I see two answers

Once you are in the bend, leant over, the geometry of the bike pushes the front wheel around the bend, even though the very large gyroscope of the front wheel is trying its damnest to run upright.

Similarly, on an open throttle, the bike is leaned over, power pouring through the rear wheel, the front wheel is off the ground (it can't be steering, can it) and the bike is still

This seems to contradict itself... How

Hi



At low speeds we steer by pointing the front wheel in the direction we want to go. The force required to turn the bike in this case is basically a friction force associated with the front wheel (combined with the fact the front wheel is contrained to roll only about its axis).

Cool But is it different for high speeds?

I always thought it was more to do with the tyre profile and the fact that there is a larger circumference at the centre of the tyre and a smaller on the outside... Therefore, a bit like putting a cotton reel on a pencil and rolling it over a desk, it will go round a corner due to the difference in diameters....

Please help me out cos this is really bugging me now