Why I wish there was an outdoor go-kart track close to me

[mst]

Originally Posted by sharky nrk

You are correct, I did describe what happens with any turn......specifically that increased velocity has the effect on increasing the force pushing you away from the center of the arc/turn. What you read/believe is incorrect, the lateral (although lateral is not the best worn since we are talking angular movement ) is not the same. That is why I posted the FBD with the formula and the relationship can be clearly seen.

I don't fully understand your diagram.

How do your "numbers" compare with this : (lean angle & lat accel calc spreadsheet) : (Specifically his "lateral acceleration" under Turn Conditions)

http://www.msgroup.org/forums/mtt/images/bike032210.xls

[sharky nrk]

^^ that is a neat spreadsheet BTW and it tells you the same story I am explaining. So on the sheet if you leave everything the same and enter 20mph in turn condition speed - you get a lateral acceleration of 21 ft/s^2 and a 321 lbf load on the rear wheel and you need around 34 deg lean at the CoG - if you increase that speed to 30 mph then your lateral acceleration just to 48 ft/s^2 and your at 722 lbf at the rear wheel and you need 56 deg lean at the CoG.

[mst]

And if you enter 60 mph for a turn radius of 360 feet, what are the resulting numbers ?

[sharky nrk]

Originally Posted by mst

And if you enter 60 mph for a turn radius of 360 feet, what are the resulting numbers ?

Yes the numbers are similar in terms of force but you changed a major parameter of the calculation - the radius of the turn opened up significantly which has the effect of reducing the angular acceleration. You can't change multiple variables in the equations and draw the conclusions.

In this particular conversation we are talking about relatively low speeds in relationship to lean angle - not low speeds in relationship to corner radius or lean angle in relationship to curve radius. In general as the speed increases, the force increases, and the lean angle has to increase in a physical relationship for a constant set of parameters (bike/rider mass, geometry of the corner, etc etc).

[asdfman]

Good ol' M13 back when his videos weren't so depressing.

[mst]

Originally Posted by sharky nrk

Yes the numbers are similar in terms of force but you changed a major parameter of the calculation - the radius of the turn opened up significantly which has the effect of reducing the angular acceleration. You can't change multiple variables in the equations and draw the conclusions.

In this particular conversation we are talking about relatively low speeds in relationship to lean angle - not low speeds in relationship to corner radius or lean angle in relationship to curve radius. In general as the speed increases, the force increases, and the lean angle has to increase in a physical relationship for a constant set of parameters (bike/rider mass, geometry of the corner, etc etc).

I think you need to re-read my previous posts

[sharky nrk]

Since we are not obviously on the same wavelength (either I misinterpreted your initial posts/or visa versa ...... or your point is just lost on me altogether as my message has been as consistent I could make it); we can let it die here and just go with a

[Motofool]

Originally Posted by sharky nrk

Since we are not obviously on the same wavelength (either I misinterpreted your initial posts/or visa versa ...... or your point is just lost on me altogether as my message has been as consistent I could make it); we can let it die here and just go with a

It seems that you are both saying the same thing.

For any combination of speed and radius of turn, same lean angle means that the same force is applied on each contact patch.

Consider that gyroscopic effect of high speed makes flicking harder but balance easier.
Balance is a little more difficult to achieve a lower speeds, but flicking is easier, due to less gyro.
That may be what M13 was referring to.

The above posted gymkhana video shows that extreme forces and lean angles can happen at low speeds.
Notice how for very small radius (rotation around cones) the speed and lean angles are less extreme.
Why?

[mst]

Originally Posted by Motofool

Consider that gyroscopic effect of high speed makes flicking harder but balance easier.
Balance is a little more difficult to achieve a lower speeds, but flicking is easier, due to less gyro.
That may be what M13 was referring to.

re: balance :

What is your response to this : ?

http://www.msgroup.org/Tip.aspx?Num=172&Set=145-180

The only time that balance plays a significant part in the control of your motorcycle is when you are traveling at slow speeds (about as fast as you can walk.)

The rider in the first (kart track) video never was going as slow as 20 km/hr, more like 40-60 km/hr.

If you agree with the msgroup article, then the "balance difficulty" is not a factor in the kart track video due to the speeds.

[allanoue]

Originally Posted by mst

re: balance :

What is your response to this : ?

http://www.msgroup.org/Tip.aspx?Num=172&Set=145-180

The only time that balance plays a significant part in the control of your motorcycle is when you are traveling at slow speeds (about as fast as you can walk.)

The rider in the first (kart track) video never was going as slow as 20 km/hr, more like 40-60 km/hr.

If you agree with the msgroup article, then the "balance difficulty" is not a factor in the kart track video due to the speeds.

"A little more difficult" is a relative term. Drop your apsalutes and relax.

[Motofool]

Originally Posted by mst

re: balance :

What is your response to this : ?

http://www.msgroup.org/Tip.aspx?Num=172&Set=145-180

The only time that balance plays a significant part in the control of your motorcycle is when you are traveling at slow speeds (about as fast as you can walk.)

The rider in the first (kart track) video never was going as slow as 20 km/hr, more like 40-60 km/hr.

If you agree with the msgroup article, then the "balance difficulty" is not a factor in the kart track video due to the speeds.

I would disagree with that article, but I would like the author to better define balance.

In my opinion, balance is always present, during slow or fast riding.
Balance means keeping the vector weight perfectly aligned with the line that connects both contact patches.
Because the dynamic nature of movement, either the rider or the steering mechanism/geometry brings back that vector over that line after each minute deviation via steering.
When we steer, we relocate that line to the opposite side of that vector, making it work to restore balance.
If you weld the steering mechanism to the frame, no bike can stay up at any speed.

Returning to your question, keeping balance at low speeds requires more dramatic and longer inputs to the steering bar in order to correct deviations from the balance conditions.

https://www.ninjette.org/forums/show...1&postcount=13

The rider of the video is using a sport riding style, but other riders would be also succesful by using a supermoto style or a Gymkhana style.
Each style has an specific goal, but as long as each bike has enough ground clearance and tire grip and each rider is smooth and gentle with suspension, they can have similar performances on this specific track.

[Elloelvi]

Originally Posted by sharky nrk

It would be because the centrifugal force is related to the square of velocity. Simplified the faster your moving around the arc of a turn, the greater the force pushing you outward - to combat this, physically you lean the bike at an angle and use this force to drive the contact patch into the surface to create additional friction force for the tire to grip.

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