Wheelie / Stoppie physics

**manuboy** · 5th December 2005, 13:52

Originally Posted by Smorgen

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

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

**bugjuice** · 5th December 2005, 14:20

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

**ManDownUnder** · 5th December 2005, 14:33

Originally Posted by bugjuice

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** · 5th December 2005, 14:34

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

**ducatilover** · 5th December 2005, 14:53

Originally Posted by ManDownUnder

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

bwahahaha bloody whale

**sAsLEX** · 5th December 2005, 14:58

Originally Posted by bugjuice

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** · 5th December 2005, 15:28

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** · 5th December 2005, 15:47

Originally Posted by ManDownUnder

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** · 5th December 2005, 17:47

Originally Posted by ManDownUnder

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

Bollocks!!

**R1** · 5th December 2005, 17:49

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** · 5th December 2005, 18:18

Originally Posted by 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.

Unless you've got a shaftee. But of course they can't wheelie anyway...

**TwoSeven** · 5th December 2005, 18:44

Originally Posted by 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.

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** · 5th December 2005, 19:18

Originally Posted by TwoSeven

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** · 5th December 2005, 19:40

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.