2018 FIM Moto GP World Championship

[Andres125sx]

J.L. being a current factory Ducati rider, & a past multiple World Champ.. or Andres' grasp of "physics" - its a tough choice.. not..

& the clincher is.. Dovi - who also took up J.L.'s aero-downforce preference.. to the extent of a front-end lose DNF, yesterday..

Sure, a front end lose is an unquestionable evidence those winglets produce useful DF while cornering


Anycase I was asking for a source to learn about the subject because I´m curious, but have never denied they produce DF, only posted what I´ve read/hear about winglets on bikes, and it´s they don´t produce DF for cornering, only aid keeping the front wheel down while accelerating

I guess that´s because bikes lean, so any DF will produce some vertical (usefull) DF, but they will mainly increase centripetal forces wich is obviously bad, because they lean around 60º so they´re closer to being parallel to the tarmac than vertical and DF will (mainly) go against grip

[nacho]

To my understanding the winglets help the most in acceleration and braking/corner entry. Where they usually cause problems are quick direction changes. Rider feeling and confidence is such a huge thing that even if the vertical downforce is negated by the horizontal push it still can make all the difference if it gives the right feeling.

[etusch]

To my understanding the winglets help the most in acceleration and braking/corner entry. Where they usually cause problems are quick direction changes. Rider feeling and confidence is such a huge thing that even if the vertical downforce is negated by the horizontal push it still can make all the difference if it gives the right feeling.

I don't think it will help for braking. Because stoppie is something you dont want like wheelie. Weight is on front wheel and you need back is at ground. Ducati feels a bit comfortable with these winglets because of long WB. If I am not wrong they can use rear tyre more at braking

[etusch]

https://www.motorsport.com/f1/news/red- ... 40037/?s=1

[J.A.W.]

J.L. being a current factory Ducati rider, & a past multiple World Champ.. or Andres' grasp of "physics" - its a tough choice.. not..

& the clincher is.. Dovi - who also took up J.L.'s aero-downforce preference.. to the extent of a front-end lose DNF, yesterday..

Sure, a front end lose is an unquestionable evidence those winglets produce useful DF while cornering


Anycase I was asking for a source to learn about the subject because I´m curious, but have never denied they produce DF, only posted what I´ve read/hear about winglets on bikes, and it´s they don´t produce DF for cornering, only aid keeping the front wheel down while accelerating

I guess that´s because bikes lean, so any DF will produce some vertical (usefull) DF, but they will mainly increase centripetal forces wich is obviously bad, because they lean around 60º so they´re closer to being parallel to the tarmac than vertical and DF will (mainly) go against grip

Andres, your multiple 'mocking emojies' once again - betray your lack of understanding..

As a machine which runs banking angles in turns, the technical dynamics of a racing motorcyle - are far more complex than your simple reductionism "physics" - purports to explain.

While the actual aero-downforce levels provided by winglets is miniscule compared to F1 values, the 'confidence'
aspect which they provide for the rider - is deemed important by them - as J.L. stated..

& Dovi's crash tested the limits of that effect, (esp' with his being equivocal about using them, as I'd duly noted),
but your jeering comment - shows how you missed that point, also..

[Nonserviam85]

So downforce doesn't help at braking? Funny to hear that at a F1 technical forum...

[nacho]

[/quote]
I don't think it will help for braking. Because stoppie is something you dont want like wheelie. Weight is on front wheel and you need back is at ground. Ducati feels a bit comfortable with these winglets because of long WB. If I am not wrong they can use rear tyre more at braking
[/quote]

Downforce in front will ensure the front is planted when braking hard. Current MotoGP bikes will basically try to wheelie the whole straight and riders are pulling themselves forward on straights.

Ducati riders use the rear brake more than others but mostly to aid turning. Mid-corner turning has been their weakness since forever.

[Andres125sx]

So downforce doesn't help at braking? Funny to hear that at a F1 technical forum...

Funny or not, bikes are far from F1 cars, their rear wheel can literally jump while braking if they take a bump because maybe 90-95% of the weight is at the front wheel while braking, so DF at the front does not help, if it would be at the rear it would be a completely different matter, but that´s not the case

I´ve read that´s one of the problems of Pedrosa in MotoGP, he´s too light and can´t load the rear end at the brakings so he literally can´t brake as hard as heavier riders, his rear wheel loose contact sooner

F1 cars don´t have any problem of a jumpy rear end, it becomes lighter too but not to the point the wheels can loose contact with tarmac as we see on MotoGP (in F1 brake balance is around 55-45% or 60-40% as much, front-rear, wich is an evidence the rear end is more planted), and the DF is more balanced so it also aids keeping the rear planted

[etusch]

I think you are missing my point. When they brake they can already make it harder without any downforce(coming from winglets) but it cause rear wheel left the ground. if there is a df to help plant front wheel to ground and they brake harder what is there to prevent that to happen unwanted stoppie. So it is not about braking harder, they don't need that.
In the other hand that winglets designed for preventing wheelie not helping to brake.

[henry]

So downforce doesn't help at braking? Funny to hear that at a F1 technical forum...

Funny or not, bikes are far from F1 cars, their rear wheel can literally jump while braking if they take a bump because maybe 90-95% of the weight is at the front wheel while braking, so DF at the front does not help, if it would be at the rear it would be a completely different matter, but that´s not the case

I´ve read that´s one of the problems of Pedrosa in MotoGP, he´s too light and can´t load the rear end at the brakings so he literally can´t brake as hard as heavier riders, his read wheel loose contact sooner

F1 cars don´t have any problem of a jumpy rear end, it becomes lighter too but not to the point the wheels can loose contact with tarmac as we see on MotoGP (in F1 brake balance is around 55-45% or 60-40% as much, front-rear, wich is an evidence the rear end is more planted), and the DF is more balanced so it also aids keeping the rear planted

F1 have a weight shift under braking of around 10%. I’m guessing that a MotoGP bike is probably nearer 50%. I can find a wheelbase figure but not CG height, so I can’t do a calc.

Another difference is that the drag vector during braking on an F1 car is around CG height and so doesn’t make much contribution to balance change. When a MotoGP rider sits up for braking the drag vector will rise and so help reduce forward weight transfer. This may be another issue for a short rider, such as Pedrosa, since he doesn’t lift the drag as high, and he can’t shift his weight as far rearwards as taller riders because of arm length. Rossi has always been regarded as good under brakes, perhaps his stature helps.

I’ve never really thought about the physics of bikes, so I may be well off.

[rscsr]

So downforce doesn't help at braking? Funny to hear that at a F1 technical forum...

Funny or not, bikes are far from F1 cars, their rear wheel can literally jump while braking if they take a bump because maybe 90-95% of the weight is at the front wheel while braking, so DF at the front does not help, if it would be at the rear it would be a completely different matter, but that´s not the case

I´ve read that´s one of the problems of Pedrosa in MotoGP, he´s too light and can´t load the rear end at the brakings so he literally can´t brake as hard as heavier riders, his read wheel loose contact sooner

F1 cars don´t have any problem of a jumpy rear end, it becomes lighter too but not to the point the wheels can loose contact with tarmac as we see on MotoGP (in F1 brake balance is around 55-45% or 60-40% as much, front-rear, wich is an evidence the rear end is more planted), and the DF is more balanced so it also aids keeping the rear planted

I remember Lorenzo saying, that he basically never used the rear brakes on the Yamaha and had to change that for the Ducati.
And regarding DF on bikes, it certainly helps during acceleration but also during cornering. This is because the bike is "more upright" than the resulting mass force of the whole bike (with the rider).

[Bill_Kar]

So downforce doesn't help at braking? Funny to hear that at a F1 technical forum...

Funny or not, bikes are far from F1 cars, their rear wheel can literally jump while braking if they take a bump because maybe 90-95% of the weight is at the front wheel while braking, so DF at the front does not help, if it would be at the rear it would be a completely different matter, but that´s not the case

I´ve read that´s one of the problems of Pedrosa in MotoGP, he´s too light and can´t load the rear end at the brakings so he literally can´t brake as hard as heavier riders, his read wheel loose contact sooner

F1 cars don´t have any problem of a jumpy rear end, it becomes lighter too but not to the point the wheels can loose contact with tarmac as we see on MotoGP (in F1 brake balance is around 55-45% or 60-40% as much, front-rear, wich is an evidence the rear end is more planted), and the DF is more balanced so it also aids keeping the rear planted

I remember Lorenzo saying, that he basically never used the rear brakes on the Yamaha and had to change that for the Ducati.
And regarding DF on bikes, it certainly helps during acceleration but also during cornering. This is because the bike is "more upright" than the resulting mass force of the whole bike (with the rider).

Exactly. He's experiencing a huge problem because he has to change a lot of things to tame the beast. Plus, his fitness level is not enough. He was literally exhausted during mid race in France.
What is interesting though, is that people say that Suzuki suits him -and it does in the extend that it's a corner bike, like Jorge- but it is different than Yamaha nonetheless. Rins for example uses a lot of rear brakes.

[J.A.W.]

So downforce doesn't help at braking? Funny to hear that at a F1 technical forum...

Funny or not, bikes are far from F1 cars, their rear wheel can literally jump while braking if they take a bump because maybe 90-95% of the weight is at the front wheel while braking, so DF at the front does not help, if it would be at the rear it would be a completely different matter, but that´s not the case

I´ve read that´s one of the problems of Pedrosa in MotoGP, he´s too light and can´t load the rear end at the brakings so he literally can´t brake as hard as heavier riders, his read wheel loose contact sooner

F1 cars don´t have any problem of a jumpy rear end, it becomes lighter too but not to the point the wheels can loose contact with tarmac as we see on MotoGP (in F1 brake balance is around 55-45% or 60-40% as much, front-rear, wich is an evidence the rear end is more planted), and the DF is more balanced so it also aids keeping the rear planted

Got references for those assertions, Andres?

Actually, N-85 & nacho are correct, whereas Andres' fundamental lack of Moto GP dynamics detail - lets him down..

As stated, very little rear brake is used, ('cept to help with cornering, as previously - & correctly, noted),
& indeed, several expensive ( slipper clutch/electronic over-ride) 'fixes' - were needed to reduce unwanted
'engine braking' effects from the high inertia big 4T engines, too.. as it happens..

Obviously, just as in F1, added downforce via aero-means - allows for harder braking to be transmitted to the
front tyre contact patch.. but.. sans anti-lock systems - it is fully incumbent on each rider to carefully modulate
the pressure applied, as the aero-downforce drops - with the speed..

[Andres125sx]

So downforce doesn't help at braking? Funny to hear that at a F1 technical forum...

Funny or not, bikes are far from F1 cars, their rear wheel can literally jump while braking if they take a bump because maybe 90-95% of the weight is at the front wheel while braking, so DF at the front does not help, if it would be at the rear it would be a completely different matter, but that´s not the case

I´ve read that´s one of the problems of Pedrosa in MotoGP, he´s too light and can´t load the rear end at the brakings so he literally can´t brake as hard as heavier riders, his read wheel loose contact sooner

F1 cars don´t have any problem of a jumpy rear end, it becomes lighter too but not to the point the wheels can loose contact with tarmac as we see on MotoGP (in F1 brake balance is around 55-45% or 60-40% as much, front-rear, wich is an evidence the rear end is more planted), and the DF is more balanced so it also aids keeping the rear planted

F1 have a weight shift under braking of around 10%. I’m guessing that a MotoGP bike is probably nearer 50%. I can find a wheelbase figure but not CG height, so I can’t do a calc.

Another difference is that the drag vector during braking on an F1 car is around CG height and so doesn’t make much contribution to balance change. When a MotoGP rider sits up for braking the drag vector will rise and so help reduce forward weight transfer. This may be another issue for a short rider, such as Pedrosa, since he doesn’t lift the drag as high, and he can’t shift his weight as far rearwards as taller riders because of arm length. Rossi has always been regarded as good under brakes, perhaps his stature helps.

I’ve never really thought about the physics of bikes, so I may be well off.

Interesting, I had never considered drag vector influence while braking, not sure if accurate, but to me it makes perfect sense

[JonoNic]

Isn't steering rake affected under heavy braking? The more vertical the rake, by lifting the rear wheel, the more unstable the bike is on turn but steering input is much faster. Also, to keep an ideal wheelbase (for handling characteristics), rake will be steeper if engine configuration or rear swingarm is takes too much wheelbase. So would a steeper rake would be less sensitive with those aero wings or not?