"Negative Steering" Please explain. 1

• Jun 23, 2003

• Thread starter
• #2

Tryan

Mechanical

May 17, 2003

33

So let me clarify Metalguy's response.If I was going down a hypothetical hill on a hypothetical bike set up on skids hypothetically would it still happen?

 

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• Jun 23, 2003

• #3

Metalguy

Materials

Jan 2, 2003

1,412

Dunno about skids, but this subject has been debated many times on motorcycle fora. Gyro forces are way too small at low speeds to have any real effect.

 

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• Jun 23, 2003

• #4

ICman

Industrial

Feb 28, 2003

165

It is called countersteering and it has been proven many times, like Metalguy says.

Check out "Proficient Motorcycling" by David Hough. He explains it in the first book, and expands on it in the second, "More Proficient Motorcycling". He's good at simple explanations.

The second book (which I am currently reading) also describes the gyroscopic effect necessary to right the bike after it leans.

If you hypothetical bike turns by leaning, it would probably work. Watch a flat-track motorcycle race sometime on TV. You'll see the bikes take a left turn while leaning left, but with the front wheel turned to the right. Countersteering in the extreme.

 

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• Jun 23, 2003

• Thread starter
• #5

Tryan

Mechanical

May 17, 2003

33

Sorry Metalguy, I did understand your explanation , as I said I've been using counter steering for 35 years, and the hypothetical bike on skids was just a polite way of taking gyroscopic effects out of the equation!! Thanks for all the input.

 

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• Jun 23, 2003

• #6

ICman

Industrial

Feb 28, 2003

165

Okay, now that you've set us up , the REAL question:

At what speed does countersteering begin?

If you're walking the bike, you turn the front wheel toward the direction you want to go. At some low speed (riding, hopefully), countersteering takes effect. I'm sure it has to do with the friction between front tire and surface, speed of the wheel, and angle of the turn.

Has anyone developed an equation for this? Is it even possible to calculate? Does the rear tire, CoG, bike weight, etc. affect the calculation?

 

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• Jun 23, 2003

• Thread starter
• #7

Tryan

Mechanical

May 17, 2003

33

Don't know about a setup, and it was a genuine question. When Metalguy gave that very simple explanation a very old light suddenly flicked on! Of course! and it probably depends on the geometry of the front forks as to the intensity of the effect! For instance if you had a bike with the forks at 90 degrees to the road it may not work at all.And at what speed ? Maybe even when stationary!!I have more thoughts but have to go.

 

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• Jun 23, 2003

• Thread starter
• #8

Tryan

Mechanical

May 17, 2003

33

Back! As I was saying, even when stationary if you balanced on the bike and pulled on the right h/bar it would probably fall to the left, without any counterbalancing from the "rider"! {I am making this up as I go so don't quote me and feel free to disagree} I think there would be too many variables to work out a usable formula, just knowing how to use it is usfull enough! Out of interest I think a graph based on the effects of counter steering might look like a fireman's helmet on a flat line ! The front of the helmet, where it touches the line,, representing 90 deg steering head angle to the horizontal and zero effect, and the rear of the helmet, where it touches the line ,representing a steering head angle parallel to the horizontal and the effect back to zero!The hump would represent the effect and would not have a numerical value as such but would show the increase - peak - decrease.Am I talking through my hat?

 

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• Jul 7, 2003

• #9

okeng

Mechanical

Jun 14, 2003

59

Motorcycles turn by leaning.

The quickest way to initiate lean is to twitch the bars the wrong way. This makes the bike lean, which makes it turn.

What the dirt-trackers do is not countersteering. My opinion is that once you start dealing with lots of wheelspin and big slip angles, there is hardly anything in the pavement world that applies.

Yes, I know that road racers now use big slip angles and slide a lot. When they do that, all the stuff they learned in the years of not doing it has to go out the window and they have become dirt trackers with a higher coefficient of friction.

Jess Davis
Davis Precision Design

 

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• Jul 9, 2003

• Thread starter
• #10

Tryan

Mechanical

May 17, 2003

33

If you take the true meaning of the word "countersteering",With counter meaning opposite direction and steering meaning the direction the vehicle is going, then I think what dirt-trackers do is exactly countersteering! Having said that,dirt oriented cars also countersteer to go around a corner and they don't lean!!Perhaps there should be a different name for the effect when a bike is on bitumen, maybe,..... Negative Steering!!

 

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• Jul 9, 2003

• Thread starter
• #11

Tryan

Mechanical

May 17, 2003

33

So what happened to Metalguy's response to my initial question, it's gone!!!

 

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• Jul 9, 2003

• #12

Metalguy

Materials

Jan 2, 2003

1,412

Good point! *I* sure didn't delete it. I see the incorrect "gyro" response is gone too. Looks like somebody screwed up.

 

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• Jul 9, 2003

• #13

okeng

Mechanical

Jun 14, 2003

59

Tryan,

You're certainly right about the terminology. I was just referring to countersteering as it applies to street bikes. What you do when you slide is a different thing but the term countersteering is certainly descriptive. It needs a name.

If anyone has metalguy's explanation saved, I'd like to read it.

 

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• Jul 9, 2003

• Thread starter
• #14

Tryan

Mechanical

May 17, 2003

33

Metalguy basically said,if you pull on the right h/bar the bike tries to fall over to the left, and vice versa.If he doesn't mind I'll try to expand!
Bike going along perpendicular with a fork angle say, 10 deg , pull on h/bar, wheel turns slightly taking the bike in that direction, momentarily .If it was a car it would simply follow the direction of the front wheel.By turning the wheel, it moves the centerline of the front wheel slightly to the right, because of the fork angle.The inertia of the perpendicular bike going straight ahead basically makes the bike fall over or lean in the opposite direction! Out of interest, would counter steering work on a bike with zero steering head angle, and axle and forks all in line with the steering head ? I'm thinking no!

 

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• Jul 9, 2003

• #15

okeng

Mechanical

Jun 14, 2003

59

Perfect. I think that's exactly what happens but I sure didn't word it that clearly.

I think it would work even with zero angle if you were moving. The centrifugal force would make the bike lean even if the fork geometry didn't. Actually, I think the centrifugal force is what does it anyway, or at least it seems to dominate at high speeds. It doesn't take much of a pull to start the turn. On the other hand, a harley takes a lot more pull than a cbr900, so rake may have something to do with it. Soft, mushy tires, wimply forks, and flexy frames may have something to do with it, too.

 

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• Jul 9, 2003

• Thread starter
• #16

Tryan

Mechanical

May 17, 2003

33

Should have put more thought into that one!Your right ,of course it's got nothing to do with fork angle, other than perhaps to vary the effect,and everything to do with centrifugal force!Should have left it with Metalguy's very simple, but exactly right, answer! Pull on h/bar and bike tries to fall over! As for a proper name for it on bitumen, probably doesn't matter all that much!!

 

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• Jul 10, 2003

• #17

Metalguy

Materials

Jan 2, 2003

1,412

Tryan,

Yes, I think you did a great job re-writing my orig. comments.

All I can add is that the effect is VERY strong-new riders should know that it's more a pressue/force that you apply to the bars rather than actually moving them much at all. The DO move, but very little.

Tonight on my way home I'll attempt to see just how much they actually move in order to use this method to get around a &quot;fast sweeper&quot;--around 80 MPH on my ZX10 Ninja. Good thing I'm in Italy.<g>

 

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• Jul 10, 2003

• Thread starter
• #18

Tryan

Mechanical

May 17, 2003

33

Do I detect a touch of sarcasm,probably justified! Wasn't trying to steal your thunder, just stimulating discussion!As I recall from school, You got 1/2 a mark for the answer and 1/2 a mark for how you got the answer, guess old habits ...........anyway be carefull on that Ninja!!

 

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• Jul 10, 2003

• #19

Metalguy

Materials

Jan 2, 2003

1,412

Er, no, didn't mean any sarcasm at all. When I use it there's usually little doubt.<g>

You have to remember that *I* didn't invent/discover this phenonena about countersteering, so no &quot;thunder&quot; is involved.

&quot;Live to ride-ride to live&quot;!

 

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• Jul 11, 2003

• #20

Metalguy

Materials

Jan 2, 2003

1,412

From last nights ride home, the amount of countersteering movement isn't visually apparent-certainly less than 1 deg. of steering-stem rotation. It's just pressure, not any significant movement.

 

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