Wheelie / Stoppie physics

[manuboy]

This mightve been discussed b4, but i couldn't figure what to search on...

What actually causes wheelies / stoppies. Like i figure it's somehow about weight / balance / energy and momentum. I figure the "centre of rotation" that the bike moves around must become the axle in question?

But when does hard braking become enough to rotate the rear end around the front and the same for wheelies - when does hard acceleration become front wheel skyward?

Duh??

[sAsLEX]

for wheelies the torque of the engine induces a rotation in the opposite direction to the rotation provided by gravity about the back wheel, when this torque exceeds the torque created by the weight of the bike/rider then the front wheel will lift


for stoppies the centre of gravity of the bike must be highish, the forwards momentum of the COG create a torque about the front wheel which is countered by the friction and stopping force of the brakes on the wheel so the bike pivots about the front wheel

really need some force diagrams so off to paint back in a bit

[White trash]

I was told, (and I'm not sure if it's correct) that during a wheelie, the front sprocket is essentially trying to "climb" the chain.

Might be a load of shit, who knows.

[bugjuice]

how can it climb? they're both stuck in the same motion.. kinda see the logic, but that's a 'cute' thing, just a bit of wank really

a wheelie in brief - the rear wheel is providing more traction and torque than the front weight is in total, so it lifts the front wheel up. The bigger the bike, the more torque it needs to lift the heavier weight.

a stoppie in brief - the front wheel is braking beyond the point of which the weight on the rear of the bike isn't enough, so it starts to lift, and thus the front wheel is doing all the braking (so that's 100% Mr LTSA-I-know-it-all bs).

As for rotating the rear wheel round during a stoppie, that's nothing to do with the amount of braking really. If the wheel is up, it's up. You're then shifting your body motion to make the rear of the bike spin around. Same for a wheelie (ish). During a wheelie, you lean your body, and can use the handlebars to help steer.

Heaps of topics on this, and heaps of 'how to's' on the net, but each rider has a slightly different way of doing stuff, and each bike will be different again. Ask Mr Skid to do a stoppie, then try a sprotsbike brakes..

[sAsLEX]

a wheelie in brief - the rear wheel is providing more traction and torque than the front weight is in total, so it lifts the front wheel up.


huh, sorry this doesn't really explain it, in a wheelie the front wheel plays little part in the macro scale of things, sure the rotational inertia can be used to steer the bike and can impact the lifting/dropping of the front wheel, but not much.

the amount of traction has no direct impact other than the amount of torque being induced from the tire would greatly drop once the tire looses traction

[Big Dave]

Might be a load of shit, who knows.

I do - you're full of it.
(and I'm not sure about the physics)

[bugjuice]

without traction, there's no grip. no grip is no good, cos it'd just spin, and the front ain't gonna come up. Didn't mention anything about the front wheel playing a huge role, just mentioned it lifts the front wheel. Stick a brick on the front then, it'll lift that instead..

[manuboy]

3 points so far to Saslex, cos he has a lovely turn of phrase (physics wise).

2 points to WT, cos unlike me he can actually do both... (and should be glad i asked the question - cos next time it goes wrong for him, he could do a quick mental calculation on the inverse square hyponuse of the torque to get it sorted.... or not)

2 points to Bug, cos i didn't want him to feel left out... and cos he said "bit of wank" which is ... nice ...

[bugjuice]

lol .

[Motu]

It's all to do with stroke and grip,you have to get the speed right....and keep within the friction circle...invarably a mess to clean up at the end.

[ducatilover]

lets just say that the front goes slower than the back.....it works for me.... and motu has another good explanation:killingme

[phoenixgtr]

I did a stoppie the other day. Wasn't intentional. Had something to do with the cage infront of me slamming on their brakes. Didn't really notice the back end had lifted up until it came back down. Very exciting. I stopped within inches of the cages bumper :niceone:

[TwoSeven]

If you go back the the thread on chain/sprockets where it was stated the rear shock extends, the answer to the wheelie question is there. Simply put, once the shock is fully extended, the chain pulls the front wheel up as the bike tries to piviot round the rear axle.

Stoppy, pretty much the front axle is dropping below its horizontal, so the force forward then turns into a lever around the front axle.

[manuboy]

If you go back the the thread on chain/sprockets where it was stated the rear shock extends, the answer to the wheelie question is there. Simply put, once the shock is fully extended, the chain pulls the front wheel up as the bike tries to piviot round the rear axle.

Stoppy, pretty much the front axle is dropping below its horizontal, so the force forward then turns into a lever around the front axle.

Nice (and 10 or something)

Cheers

[Smorg]

blah blah blah...........................drop the clutch open the accelerator figure it out for yourself:rockon: :yes:

[manuboy]

blah blah blah...........................drop the clutch open the accelerator figure it out for yourself:rockon: :yes:

blah blah blah ... Why? When i can have somebody else figure it out for me?...

[bugjuice]

cos it's only when you do it yourself that you understand what's going on. Else it's all just words.

[ManDownUnder]

cos it's only when you do it yourself that you understand what's going on. Else it's all just words.

Only way I'll ever lift the front of the RF is with a crane... and a big one at that!

[Sniper]

You need top experiment to find your limits, but remember, its inevidible that you will crash. :lol:

[ducatilover]

Only way I'll ever lift the front of the RF is with a crane... and a big one at that!
bwahahaha bloody whale:nya: :moon:

[sAsLEX]

cos it's only when you do it yourself that you understand what's going on. Else it's all just words.

there is alot of things in life that you cant just do to understand.

Quantum physics etc can be a bit difficult to practice, but some people claim to understand.

If you understand first what makes something happen then it is more a relisation when you can achieve something like a wheelie!

[MisterD]

Newton's laws (I forget which is 1,2 and 3, but...)

1) If all forces on an object are equal, it will continue in a straight line at a constant velocity.

2) Force = mass x acceleration (or Acceleration is Force divided by the mass it acts on)

3) Action and reaction are equal and opposite.

Therefore: as your engine turns your rear wheel there is an equal and opposite force trying to turn the bike back around the wheel. If this force is larger than the weight of the front end...wheelie.

A stoppie is the same thing in reverse, but you are applying a force with your front brake to accelerate you backwards, so your rear wheel comes up this time.

[vifferman]

Only way I'll ever lift the front of the RF is with a crane... and a big one at that!
That's a bit sad!
The VFR will wheelie, and it's supposedly heavier and less powerful than the RF, isn't it?

[**R1**]

Only way I'll ever lift the front of the RF is with a crane... and a big one at that!Bollocks!!

[**R1**]

And im not sure how the phisics of it all works, but i do know that if ya cant wheelie and stoppy your ghey.... and R1's must have good phisics coz they wheelie and stoppy great!!

[Hitcher]

I was told, (and I'm not sure if it's correct) that during a wheelie, the front sprocket is essentially trying to "climb" the chain.

Might be a load of shit, who knows.
Unless you've got a shaftee. But of course they can't wheelie anyway...

[TwoSeven]

Newton's laws (I forget which is 1,2 and 3, but...)

1) If all forces on an object are equal, it will continue in a straight line at a constant velocity.


I would suggest that if this rule were true, then the object would be stationary. Since according to your rule three, if there is a force trying to push the object in one direction, there must be an equal and opposite force pushing it back.

[crash harry]

I would suggest that if this rule were true, then the object would be stationary. Since according to your rule three, if there is a force trying to push the object in one direction, there must be an equal and opposite force pushing it back.

Nope. If all forces are balanced then there is no acceleration or deceleration. That includes ALL forces, so friction etc.

So lets say you had an amazing frictionless motorcycle and you lived on the moon (no atmophere so no air friction). If you were riding along at 100km/h and you pulled in the clutch (no friction remember) then all the forces involved would be balanced and the bike would continue at 100km/h indefinitely. However, if you applied the brakes the action of the brakes and the front wheel would apply a force opposing the motion and causing the bike to decelerate (assuming THEY had friction) .

As for forces being balanced, the "equal and opposite reaction" in this case is being supplied through the friction of the tyre by the moon, which will alter slightly in it's rotation. (yes I am saying that every time you accelerate or brake you are affecting the earth's spin and/or orbit. Just a tiny bit. Everytime you walk for that matter, or even roll over in bed... However, you must stop again at some point which applies the same force in the opposite direction. Over time the effect cancels out.)

Every action has an equal and opposite reaction. You can't argue with Newton (well, you can try but he's been dead a long time so I doubt he'll pay much attention...)

WOW. I must have had a long day.
Most. Ridiculous. Post. Ever.

[avgas]

I like Statics and Dynamics 101.....
in stoppie......front tyre stops, bikes momentum throws weight of bike (which is a force), over front axel in rotational motion....energy transfered in a rotational torque type effect and when its out the wheel goes back down. More weight over front, less torque required (gravity vs balance)
in a wheelie....almost the opposite, rotational torque of wheel being sufficent to have enough torque to rotate bike in opposite direction (ie too fast acceleration to speed ratio). Energy changed as rotational force pushes bike over back axel....and eventually is returns.... unless you can provide more energy to it.
More weight over back axel, less torque required.

[Smorg]

Only way I'll ever lift the front of the RF is with a crane... and a big one at that!


Balls Ive seen one being flipped:doh:

[Skyryder]

Balls Ive seen one being flipped:doh:

Bloody hell I have enough trouble trying to figure the counter steering equation let alone this wheelie/stoppee bullshit. So my postulatiuon on the subject is this.

Whhelies=clutch and throttle corordination..........or lack off.

Stoppeise= jobbeise (that's the polite word for shit)

Skyryder

[TwoSeven]

Nope. If all forces are balanced then there is no acceleration or deceleration. That includes ALL forces, so friction etc.


Hmm. what started the object moving in the first place then ?


I know what you are trying to say - just dont think it came out right is all :)

I think you meant: "Every object in a state of uniform motion tends to stay in that state unless an external force is applied to it" - which is newtons 1st law.

Newtons 3rd law - the equal and opposite one is a bit dodgy - applied to the above, if you push an object it will move (the action) - But it also means that you must have pushed against something else in the opposite direction which offered up more resistance (the reaction).

So both laws applied, if you push something - it will keep moving until something stops it :)

[Good Girl]

blah blah blah...........................drop the clutch open the accelerator figure it out for yourself:rockon: :yes:

I been trying the whole wheelie Buzz, and found that as long as your awear of how much you have to accelerate you should be sweet.
If in doubt hit the back break and have controll.
STAY :calm:

I must admit first time I pulled a wheelie I was so stoked to get it up I ended up running after the thing, an ugly end for my poor 125 :weep:

First time generally counteracts with a funk-up. But that's ok :niceone:

[ducatilover]

And im not sure how the phisics of it all works, but i do know that if ya cant wheelie and stoppy your ghey.... and R1's must have good phisics coz they wheelie and stoppy great!!
yup r1's are kewl..... my gn could lift off in second if you changed with no clutch and gave it heaps [whilst nearly killing it]:killingme

[Mental Trousers]

mmmm, my turn.

With a wheel stand, if you accelerate there are 3 main forces acting on the bike - thrust, momentum and gravity. Genereally what happens is that the centre of gravity (CoG) is above that of the centre of thrust (CoT). When you have this situation, the thrust forward is below the momentum which is pushing back. This offset of the CoG and CoT produces another force - Lift. Once Lift is greater than Gravity, the front end leaves the ground and you solo down the road like some sort of god.

A stoppy is the same but opposite - the thrust is backwards while the momentum is pushing forwards. Same thing, just a mirror.

What happens with the sprockets and chain is different. The front sprocket is trying to pull the chain forward at the top. The rear sprocket is trying to resist the chain being pulled, also at the top. Now because the centre of both sprockets is offset from one another, this again produces another force - that of lift at the front sprocket. So the front sprocket will try to climb, adding to the lift produced in the paragraph second above this one.

[Big Dave]

Regardless of what they climb - Some are easier to get up than others.
Stretch is a legend.

[ducatilover]

Regardless of what they climb - Some are easier to get up than others.
Stretch is a legend.
holy mutha fuken moses sack.:drinknsin :spudwhat:

[ducatilover]

:stupid:
mmmm, my turn.

With a wheel stand, if you accelerate there are 3 main forces acting on the bike - thrust, momentum and gravity.
momentum? aint that the same as thrust? hang on no.....okay i'm good cary on...



but does momentum act upon an object? isnt the momentum the result of the forces applied?

[T.W.R]

its about balance & feeling the bike

this ones a fairly impressive stand-up:niceone:

[Mattyc]

Only way I'll ever lift the front of the RF is with a crane... and a big one at that!

BWAAAAAAAAAAAAAAAHAAAAA ROFL COPTER:chase: :chase:

[Mattyc]

. Now because the centre of both sprockets is offset from one another, this again produces another force - that of lift at the front sprocket. So the front sprocket will try to climb, adding to the lift produced in the paragraph second above this one.

WT was right AUU

Chuck Norris could wheelie an RF 900

! can wheelie my zx9, its a bit of a heffer tho - havent tried any intentional stoppies yet, the mx bike is fun to do them on, specially the mrs bike

[bugjuice]

crash harry, why the hell are you on about the moon now?


wheelies ain't hard to do, just hard to refine. Go play wiv yerself and find out.

[MisterD]

Newtons 3rd law - the equal and opposite one is a bit dodgy - applied to the above, if you push an object it will move (the action) - But it also means that you must have pushed against something else in the opposite direction which offered up more resistance (the reaction).

So both laws applied, if you push something - it will keep moving until something stops it :)

This is always something that confuses people, action and reaction means if you push something then it pushes back at you equally. So if you push against something which cannot move, you will slide backwards, see?

[Hitcher]

its a bit of a heffer tho
It's a bit of a heifer though [Courtesy of Hitcher's Editing Services, a wholly-owned subsidiary of English As A First Language Ltd]

[Smorg]

MOOOOOOOOOKKKKK!!!!!!!

[Mattyc]

It's a bit of a heifer though [Courtesy of Hitcher's Editing Services, a wholly-owned subsidiary of English As A First Language Ltd]

cheers Hitcher, least you knew what i meant

[Marmoot]

A wheelie is caused by the jet of exhaust gas that overcomes the weight of the front.
That is why wheelies are normally done at high RPM, so that the exhaust emission is at higher speed and provides higher thrust. And this is also why wheelies are easier done on sportsbike, due to the exhaust pipe angled upwards, pushing the rear of the bike down and lifting the front up (see: Momentum and Power-Coupling) in a similar way an end of a see-saw move upwards if you push the other end down.

Stoppies, on the other hand, has nothing to do with exhaust gas. It happens normally when a rider is bold enough to properly decelerate as hard as he can. As long as front tyre traction is not exceeded, the front wheel will not lock up causing the bike to crash.
When the rider is bold enough, it is normally caused by a surge in testosterone level (testosterone causing man-ego and desire to impress). This surge of hormone in the glandular area increases the liquid mass up to the n-th degree. When the courage generated induces braking, the liquid mass sloshes front-ward, causing frontward momentum. This momentum is normally above the bike's centre-of-gravity, and combined with steep steering angle of sportbikes this momentum causes another power-coupling similar to wheelie but to the other direction (refer to: Clockwise and Anti-clockwise) and pushes the front down while lifting the rear up.

I hope that explains how wheelie and stoppie happens, and why it is much easier to induce them on sportsbike. :yes:

[TwoSeven]

My question is - if your riding a motorcycle in reverse and you hit the rear brake causing the front wheel to lift - is that a wheelie or a stoppie ?

[avgas]

My question is - if your riding a motorcycle in reverse and you hit the rear brake causing the front wheel to lift - is that a wheelie or a stoppie ?
Stoppie....cos you stopped

[crash harry]

My question is - if your riding a motorcycle in reverse and you hit the rear brake causing the front wheel to lift - is that a wheelie or a stoppie ?

I think that needs a new name... I think if I did it my audience would call it "Oh look, he's crashed his bike!", whereas I would call it "Aaarrrgh!!! Get this thing offa me!"

[crash harry]

crash harry, why the hell are you on about the moon now?


Do I need a reason to talk about the moon? I like the moon.

Okay, I'm having one of those weeks where I don't make much sense apparently. I thought I'd inflict it on KB for some reason.

[skidMark]

i wouldve thought it would be something to do with traction i mean you lean out the back a) the COG is further back and b) more traction on back so instead of slipping with all the power it forces to hard that it lifts the front wheel i mean if you have enough traction and power you can wheelie anything

you can have all the power in the world....but with no traction youll just be smoking your tyres lol

don't care about the physics really they r just a hell load of fun to do :2thumbsup

[Hitcher]

Everybody thinks they're Stephen Fucking Hawking.

[sAsLEX]

Everybody thinks they're Stephen Fucking Hawking.

wHo isked u?! iF wE wants you're oppionion we wud aks for it

[skidMark]

wHo isked u?! iF wE wants you're oppionion we wud aks for it


but he has a cool avatar and for that alone his posts are valid even though it's rather sad but in some way impressive he has over 6000 posts lol

[Mental Trousers]

Momentum tries to preserve the current state of something, so if you give a bike some thrust forward, momentum will always push backwards and vice versa. Laws of Energy Conservation blah.

[Mattyc]

while you guys have been blithering on i have been out doing wheelies, its as simple as this pull in the clutch a little, rev the bitch, drop clutch, twist throttle, maintainin balance on back wheel until asshole starts to pucker slowly ease it down with the throttle in an effort to not crush your nuts.\

Not game for stoppies on the zx9 til i get some oggy's fitted, on the mx bike they are easy as shit, slam on the front brake while sort of pushing down and back on the pegs , forward on the bars - sort of hard to explain, i pulse the front brake and roll a little ....

I really can't see what all the fucken blithering is about - just go try them

:spudbooge :eyepoke:

[Marmoot]

you can have all the power in the world....but with no traction youll just be smoking your tyres lol

don't care about the physics really they r just a hell load of fun to do :2thumbsup

bah....you can have all the power in the world and all the traction you can get, but without the exhaust gas jet pointed upwards you'll just accelerate like a bullet. :eyepoke:

[Marmoot]

Not game for stoppies on the zx9 til i get some oggy's fitted, on the mx bike they are easy as shit, slam on the front brake while sort of pushing down and back on the pegs , forward on the bars - sort of hard to explain, i pulse the front brake and roll a little ....

I really can't see what all the fucken blithering is about - just go try them

:spudbooge :eyepoke:

And this one.....without significant testicular fluid motion you will not be able to do stoppies as there is not enough momentum to help the bike.
That's why when someone did massive stoppies, especially in unfavourable surface, people would normally utter "Gosh, he has BIG balls" due to him controlling bigger glandular liquid ability.

And that's why more guys do stoppies than girls, although lactating glands can also be utilized to help in abscense of testicular equipment, albeit being harder to control due to longer momentum arm distance (located further from bike's Centre of Gravity).

[Mattyc]

And this one.....without significant testicular fluid motion you will not be able to do stoppies as there is not enough momentum to help the bike.
That's why when someone did massive stoppies, especially in unfavourable surface, people would normally utter "Gosh, he has BIG balls" due to him controlling bigger glandular liquid ability.

And that's why more guys do stoppies than girls, although lactating glands can also be utilized to help in abscense of testicular equipment, albeit being harder to control due to longer momentum arm distance (located further from bike's Centre of Gravity).

I Concurr!!!!!!!!!!!!!!!!!!!

[Hitcher]

I Concurr!!!!!!!!!!!!!!!!!!!
As in "divide and concurr"? [Hitcher's tip du jour: to quickly check spelling of a word, type "define (whatever the word is)" into your Google search window and hit Enter. Or go to www.dictionary.com]

[Mattyc]

as in I conCURRRRRRRRRRR ! lol

:eyepoke:

[TwoSeven]

..........

Here (http://www.ilovewavs.com/TV/Cartoons/Simpsons/Bart/Concur.wav)

[Deviant Esq]

As far as how they work, I'd say that's been sufficiently explained. In some form or another :blink:

As far as how they look, here's a wee vid I found of stunt wheelies and stoppies (and a few drops as well!:doh:)

:2thumbsup

http://video.google.com/videoplay?docid=2481717561843851052&q=motorcycle

[thehollowmen]

this thread has given me and a physics PhD here the best laugh we've had for a while :-)

kudos

[Marmoot]

this thread has given me and a physics PhD here the best laugh we've had for a while :-)

kudos

yea man. Those who argued about torque, traction and sprockets surely don't know about anything. To know the real answer to wheelies/stoppies issue you'd be better off asking to doctors and biologist. The real answer lies in your body (around your testicles) :first:

[MisterD]

yea man. Those who argued about torque, traction and sprockets surely don't know about anything. To know the real answer to wheelies/stoppies issue you'd be better off asking to doctors and biologist. The real answer lies in your body (around your testicles) :first:

You're just dispalying your own ignorance there Marmoot, a man as well read as you obviously are should know that when you get right down to it, everything is a branch of Physics....

[Marmoot]

You're just dispalying your own ignorance there Marmoot, a man as well read as you obviously are should know that when you get right down to it, everything is a branch of Physics....

Physics as in "let's get physical"?
That'd be true. As long as it involves human body and sexual organ, I'm in (preferably ones without testicular feature on it).

[MisterD]

"let's get physical"?


Olivia Neutron-Bomb, I rest my case. :doobey:

[manuboy]

this thread has given me and a physics PhD here the best laugh we've had for a while :-)

kudos

I Concurr!!!!!!!!!!!!!!!!!!!

[dawnrazor]

This mightve been discussed b4, but i couldn't figure what to search on...

What actually causes wheelies / stoppies. Like i figure it's somehow about weight / balance / energy and momentum. I figure the "centre of rotation" that the bike moves around must become the axle in question?

But when does hard braking become enough to rotate the rear end around the front and the same for wheelies - when does hard acceleration become front wheel skyward?

Duh??
Okay you've got the "law of the lever" saying force, pivot, load, add to this some speed and weight transfer, and suddenly the load decreases and the force increases in the case of a wheelie or the oppisite in the case of a stoppie, if the lever is balanced before the other factors act on it.

the pivot is the fixed point