Limit cornering on bikes

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Andres125sx
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Joined: Tue Aug 13, 2013 9:15 am
Location: Madrid, Spain

Re: Limit cornering on bikes

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J.A.W. wrote:
Sun Mar 08, 2020 11:09 am

No Andres, you surely cannot be serious...

What is "laughable", is that you can possibly imagine that professional experts in their field,
do not/are not fully capable of, (even when expected to) - providing expert feedback on the
basis of a very real, & thorough, understanding of the needful rider-feedback systems of the
super-high performance machine - they must master to enable the very best likehood of a title-win.

(Ask yourself why ex-champions, yet still fairly recent, & fit/active, such as Stoner & Lorenzo
are so sought after by teams to provide even more expert test-rider feedback...)
You´re confusing providing feedback with a deep understand of the physics behind motorcycling, and they´re completely different.

You don´t need any engineering understanding to know the bike is oversteering at the exit of a corner too easily, or the rear suspension is too soft, or TC need to allow some more oversteer, or the frame is not allowing a smooth corner entry.

To provide feedback you only need experience riding motorcycles, wich obviously any MotoGP, Moto2 or Moto3 rider enjoy in excess, to know if the bike is performing ok or has some problem or something to improve. If the bike cannot enter a corner smoothly the rider does not care and does not know the engineering explanation for that, he only knows the bike should enter corners better

Or you think those 15 years old riders know something about engineering when they didn´t even studied basic maths yet? :lol:

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strad
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Joined: Sat Jan 02, 2010 12:57 am

Re: Limit cornering on bikes

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I have to agree with Andres on this. The riders can jump on and push a bike to it's limits and come back in and say it does this wrong or that is does this or that right but they could not engineer a motorcycle.
They know what happens when they do A or B but not necessarily know why. :wink:
If a rider/driver knew what the engineers know we wouldn't need engineers.
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss

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Tim.Wright
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Joined: Fri Feb 13, 2009 5:29 am

Re: Limit cornering on bikes

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This is also exactly my experience on the matter.
Not the engineer at Force India

Jolle
Jolle
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Location: Dordrecht

Re: Limit cornering on bikes

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Yes they perhaps don't know all the engineering stuff but feeling all the gyroscopic effects and working with them, is biker/racer 101.

Just like Ducati's locking rear spring for the starts. The rides probably don't have a clue how it works, but they feel the grip. Another one is MM his corner exit. One of the reasons he's so good, he figured out quite early that a bike leaning but going straight can accelerate harder then when the bike is upright. This is because the CoG is lower and the contact patch of the tire is bigger. Seems so logical...

Slo Poke
Slo Poke
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Joined: Thu Apr 11, 2019 11:14 am

Re: Limit cornering on bikes

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Hi Erunanethiel:
In a steady state ‘limit’ cornering situation a bike shouldn’t be able to stand back up because (it has to countersteer into the turn), momentarily carving a tighter line than before. But if it is at the edge of traction, it can’t.

Countersteer is merely a tool for the box and should be left there until an experienced fast rider spots a reason good enough to use it. It works exactly as they say but with over-use you will eventually find yourself in a self-inflicted crazy-caster or tankslapper situation. In a steady state corner, such as parabolica Monza, it’s sometimes warranted to counter out caster angle and that’s achieved by applying gentle pressure on the right hand, inside handlebar grip or clip-on. It could easily be mistaken for countersteer but it isn’t, it’s cancelling out caster. Countersteering is best kept where I suspect it came from (strangely, as far as I’m concerned, in road safety).
When a motorcyclist becomes comfortable and at ease with a bike he/she realises at some point that he/she is not alone. Bikers are never truly alone as they always have a trustworthy attendant along with them, on every trip out they make. That applies to any two wheeled vehicle and the attendant is known as Gyroscopics from not one wheel but two. Uni cyclists are the only bike riders that truly go it alone, plus they’ll be forever unique in having to use countersteer.
Gyroscopics provide just one component and it’s simply stability through damping. Within reason damping allows the rider to move around on the bike and any two wheeled vehicle operator needs a degree of lateral freedom to move their weight around. They must do in order to make the bike do what they want it to, otherwise the bike will tend to control them. At liberty to move around many riders hang off the bike in corners and any such rider is not only minimising centrifuge but is also bringing or maximising aerodynamics into the equation. Rather like the infinity wings that the BTCC guys have recently adopted, as the philosophy goes it adds a little extra weight to the front contact patch. When exiting a corner, or at least post apex, riders tend to centralise their body weight in a way that harmonises the shift to the dissipating influence of centrifuge pivoting the bike from the rear contact patch, as the front wheel should have already gone light under acceleration.
When a rider parts company from a bike we often see a wayward and riderless bike and the reason it can become riderlessly upright is because of caster angle and gyroscopics guide it to the armco. One aspect is engineered in to provide drivability and the other is a force of nature usefully able to provide bike riders in general a far safer and controllable feel.
At speed, post apex under high acceleration you really don’t want to be messing with what you termed as countersteer.
If motorcycles frighten anyone at all, or you get the idea that someone isn’t too fluent riding them, then do that person a favour and advise them to buy a car.

Erunanethiel, I have to ask as you state ‘it has to countersteer into the turn’. From where did you acquire that nugget of information? Wasn’t a road safety school was it? If that’s the case then, don’t go back there.

J.A.W.
J.A.W.
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Re: Limit cornering on bikes

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strad wrote:
Mon Mar 09, 2020 7:44 pm
I have to agree with Andres on this. The riders can jump on and push a bike to it's limits and come back in and say it does this wrong or that is does this or that right but they could not engineer a motorcycle.
They know what happens when they do A or B but not necessarily know why. :wink:
If a rider/driver knew what the engineers know we wouldn't need engineers.
Nah, sorry strad, but we are now - just 'bout into the 3rd decade of the C21st,
& your ideas are long out of date, ok, so yeah, Honda 50+ years ago might've accepted
the awesome natural talent of Mike Hailwood, to simply climb aboard their unruly 500
& fearlessly max it out, while being unconcerned/uninterested in 'the technical stuff',
as the myriad of HRC technicians fussed 'n' fettled their machine - but no longer*...

When even the likes of super-contained 35 y/o Lewis Hamilton is taken aback at the inputs
needful for the big bikes, there is no need to wonder why the younger Marquez is, too (despite
his father claiming he had more riding talent than Marc, at one stage), any Champion must
indeed have a thorough understanding of the essential functions at his disposal, in order to
provide effective feedback to his team.

This was a cogent lesson Honda learned from Hailwood's loss to the analytical Agostini, &
again from Doohan later on, plus Stoner too, & most recently, when they 'released' both Pedrosa
& then Lorenzo, when they could not 'gel' with the bike, nor explain to HRC, what was really
needed to do so.

*I'd suggest that those who do not get this, should read the memoirs of Chuck Yeager, for
an apt analogy, since Yeager was both a 'natural' (& ace) fighter pilot with excellent 4D
proprioceptive flying skills, yet also possessed a functional grasp of the technical systems,
thus making an exceptional record-breaking (yeah, the 'big one', the dreaded 'Sound Barrier')
test-pilot too, as he was very able to discuss effectively, his 'hands-on' experiential concerns
with the engineers below, & so ensure the needful modifications were properly conveyed.
Last edited by J.A.W. on Tue Mar 10, 2020 11:25 am, edited 1 time in total.
Dr Moreau sez..
"Who breaks the law... goes back to the House of Pain!"

Tommy Cookers
Tommy Cookers
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Joined: Fri Feb 17, 2012 3:55 pm

Re: Limit cornering on bikes

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so who/where are (e.g.) today's Peter Williams or John Surtees ?
or engineering graduates (ha !) like Nigel Mansell ?

btw
Yeager was (unlike others) most untrained for the job (that was to develop concerns and convey them)
importantly though being a maintenance test pilot based on a dry lake he was skilled with the landing issue there
twice (X2 and reaction-control F104) he blew his mission via inaccuracy or otherwise breaching the flight envelope
(Bell's test pilot Goodlin wanted millions to break the sound barrier - so Y was given the job to do it at normal pay rate)

I have video footage of his 51 crossing my nose at Kissimmee

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strad
271
Joined: Sat Jan 02, 2010 12:57 am

Re: Limit cornering on bikes

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@JAW.. I think the most cogent statement in this thread is this
You´re confusing providing feedback with a deep understand of the physics behind motorcycling, and they´re completely different.
I can't tell you how many times I have seen riders/drivers completely misled by seat of the pants feel.
It's why we have engineers trained to read the real feed back from sensors. And why being able to correlate lap times, corner speeds and all the computerized information from the myriad of sensors is so valuable. It's why those engineers get paid their well earned salaries. I don't think race teams would waste the money if they only needed a driver to tell them what they needed to change. I don't think even a Chuck Yeager could engineer a better plane but only supply feedback as to whether a certain change made a problem better or worse.
But you are of course entitled to your opinion. :wink:
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss

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Tim.Wright
464
Joined: Fri Feb 13, 2009 5:29 am

Re: Limit cornering on bikes

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Drivers drive. Engineers engineer.

Hero worshipping aside, there hasn't been any overlap in these two disciplines in motorsport for at least 40 years now.
Not the engineer at Force India

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strad
271
Joined: Sat Jan 02, 2010 12:57 am

Re: Limit cornering on bikes

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1980? I'd say more than 40. :wink:
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss

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SectorOne
392
Joined: Sun May 26, 2013 8:51 am

Re: Limit cornering on bikes

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Slo Poke wrote:
Tue Mar 10, 2020 10:19 am
Hi Erunanethiel:
In a steady state ‘limit’ cornering situation a bike shouldn’t be able to stand back up because (it has to countersteer into the turn), momentarily carving a tighter line than before. But if it is at the edge of traction, it can’t.

Countersteer is merely a tool for the box and should be left there until an experienced fast rider spots a reason good enough to use it. It works exactly as they say but with over-use you will eventually find yourself in a self-inflicted crazy-caster or tankslapper situation. In a steady state corner, such as parabolica Monza, it’s sometimes warranted to counter out caster angle and that’s achieved by applying gentle pressure on the right hand, inside handlebar grip or clip-on. It could easily be mistaken for countersteer but it isn’t, it’s cancelling out caster. Countersteering is best kept where I suspect it came from (strangely, as far as I’m concerned, in road safety).
When a motorcyclist becomes comfortable and at ease with a bike he/she realises at some point that he/she is not alone. Bikers are never truly alone as they always have a trustworthy attendant along with them, on every trip out they make. That applies to any two wheeled vehicle and the attendant is known as Gyroscopics from not one wheel but two. Uni cyclists are the only bike riders that truly go it alone, plus they’ll be forever unique in having to use countersteer.
Gyroscopics provide just one component and it’s simply stability through damping. Within reason damping allows the rider to move around on the bike and any two wheeled vehicle operator needs a degree of lateral freedom to move their weight around. They must do in order to make the bike do what they want it to, otherwise the bike will tend to control them. At liberty to move around many riders hang off the bike in corners and any such rider is not only minimising centrifuge but is also bringing or maximising aerodynamics into the equation. Rather like the infinity wings that the BTCC guys have recently adopted, as the philosophy goes it adds a little extra weight to the front contact patch. When exiting a corner, or at least post apex, riders tend to centralise their body weight in a way that harmonises the shift to the dissipating influence of centrifuge pivoting the bike from the rear contact patch, as the front wheel should have already gone light under acceleration.
When a rider parts company from a bike we often see a wayward and riderless bike and the reason it can become riderlessly upright is because of caster angle and gyroscopics guide it to the armco. One aspect is engineered in to provide drivability and the other is a force of nature usefully able to provide bike riders in general a far safer and controllable feel.
At speed, post apex under high acceleration you really don’t want to be messing with what you termed as countersteer.
If motorcycles frighten anyone at all, or you get the idea that someone isn’t too fluent riding them, then do that person a favour and advise them to buy a car.

Erunanethiel, I have to ask as you state ‘it has to countersteer into the turn’. From where did you acquire that nugget of information? Wasn’t a road safety school was it? If that’s the case then, don’t go back there.
What a load of rubbish.
"If the only thing keeping a person decent is the expectation of divine reward, then brother that person is a piece of sh*t"

Slo Poke
Slo Poke
1
Joined: Thu Apr 11, 2019 11:14 am

Re: Limit cornering on bikes

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SectorOne wrote:
Thu Mar 12, 2020 5:27 pm
Slo Poke wrote:
Tue Mar 10, 2020 10:19 am
Hi Erunanethiel:
In a steady state ‘limit’ cornering situation a bike shouldn’t be able to stand back up because (it has to countersteer into the turn), momentarily carving a tighter line than before. But if it is at the edge of traction, it can’t.

Countersteer is merely a tool for the box and should be left there until an experienced fast rider spots a reason good enough to use it. It works exactly as they say but with over-use you will eventually find yourself in a self-inflicted crazy-caster or tankslapper situation. In a steady state corner, such as parabolica Monza, it’s sometimes warranted to counter out caster angle and that’s achieved by applying gentle pressure on the right hand, inside handlebar grip or clip-on. It could easily be mistaken for countersteer but it isn’t, it’s cancelling out caster. Countersteering is best kept where I suspect it came from (strangely, as far as I’m concerned, in road safety).
When a motorcyclist becomes comfortable and at ease with a bike he/she realises at some point that he/she is not alone. Bikers are never truly alone as they always have a trustworthy attendant along with them, on every trip out they make. That applies to any two wheeled vehicle and the attendant is known as Gyroscopics from not one wheel but two. Uni cyclists are the only bike riders that truly go it alone, plus they’ll be forever unique in having to use countersteer.
Gyroscopics provide just one component and it’s simply stability through damping. Within reason damping allows the rider to move around on the bike and any two wheeled vehicle operator needs a degree of lateral freedom to move their weight around. They must do in order to make the bike do what they want it to, otherwise the bike will tend to control them. At liberty to move around many riders hang off the bike in corners and any such rider is not only minimising centrifuge but is also bringing or maximising aerodynamics into the equation. Rather like the infinity wings that the BTCC guys have recently adopted, as the philosophy goes it adds a little extra weight to the front contact patch. When exiting a corner, or at least post apex, riders tend to centralise their body weight in a way that harmonises the shift to the dissipating influence of centrifuge pivoting the bike from the rear contact patch, as the front wheel should have already gone light under acceleration.
When a rider parts company from a bike we often see a wayward and riderless bike and the reason it can become riderlessly upright is because of caster angle and gyroscopics guide it to the armco. One aspect is engineered in to provide drivability and the other is a force of nature usefully able to provide bike riders in general a far safer and controllable feel.
At speed, post apex under high acceleration you really don’t want to be messing with what you termed as countersteer.
If motorcycles frighten anyone at all, or you get the idea that someone isn’t too fluent riding them, then do that person a favour and advise them to buy a car.

Erunanethiel, I have to ask as you state ‘it has to countersteer into the turn’. From where did you acquire that nugget of information? Wasn’t a road safety school was it? If that’s the case then, don’t go back there.
What a load of rubbish.
Sector One! I’m completely at a loss! ‘What a load of rubbish’ you say! Whatever do you mean? I mean! Seriously. What minor part of the discourse I’ve presented, could possibly be throwing you?
Please! Pray tell, I beg you, enlighten me.

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strad
271
Joined: Sat Jan 02, 2010 12:57 am

Re: Limit cornering on bikes

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Sector One; I'm thrown by your use of the word caster. Are you referring to the "trail"
That is created by neck angle? Is it not? :?
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss

joshuagore
joshuagore
1
Joined: Fri Feb 12, 2010 3:01 am

Re: Limit cornering on bikes

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At the limit, counter steer relates to the slip angle of the tire carcass as much as it does to do with stability or self centering forces(they are related). There is decently complicated math behind all this done by Jim Papadopoulos https://www.nature.com/news/the-bicycle ... cs-1.20281 or you can go back to the work of Tony Faole in Motorcycle Chassis and Handling and Dynamics.

I have been building riding and tinkering with zero trail or reducing trail suspension, and traditional suspension using bicycles and the larger 'mid fat' tire carcasses available to better understand what is going on when the limit of traction and countersteer is applied. I have noticed countersteering at the limit to be at least partially influenced by the spring rate of the tire, carcass and its construction(tpi, and ply orientation maybe?). This is at the lower speeds of bicycles so some of the behavior is easier to perceive or document(capture on consumer cameras, or cheaper data loggers). Maybe the ultra thin bike tire/carcass has no analogous comparison to what is being done with a prototype road racer on slicks, but I would guess some of what I have observed is transferable.

What I will say is this, on a zero trail setup, or negative trail front suspension I CAN ride no handed, but it isn't always easy, if I reduce tire pressure, a moment occurs where I believe the tires slip angle and the resulting torsional spring force induces an oscillation. This oscillation is harder to evoke with higher pressure in the tire, a stiffer carcass, or a reduced slip angle due to smaller tire volume.

Some of these characteristics are hard to feel until you remove the natural self correction of more trail. When you reduce the trail your arms are now woefully aware of the forces going into loading the tire and keeping it straight, in that moment you certainly feel the tire load up and in video you can observe the carcass deflect, and the user respond, a response which may have been partially natural in a bike setup with the proper trail.

https://joshgoreworks.com/linkage-forks/

Just my 2 cents.

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strad
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Joined: Sat Jan 02, 2010 12:57 am

Re: Limit cornering on bikes

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thank you. Interesting links there. =D>
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss