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Help Me Understand...


Stroker
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I was watching this Moto Gymkhana video and am trying to work this out -

 

They counter steer to weave in between the cones.But when they do U turns and circles, they are turning the bars right to go right and left to go left...?

 

Are they initiating the U turns and circles by countersteering and then turning the bars right to go right and left to go left...?

 

 

Help me understand this? Thanks

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Stroker, I may edit my reply tomorrow :)

 

What is a countersteer and what does it do?

But when they do U turns and circles, they are turning the bars right to go right and left to go left...? Just a second...

Are they initiating the U turns and circles by countersteering and then turning the bars right to go right and left to go left...? You have won the prize. Why would you want to countersteer before such a maneuver? What are the benefits for countersteerings in these situations? And why would you then turn the bars to the right to go right or left to go left afterwards?

What did you notice about the riders in the video? Which ones would you think are the better riders, and why?

 

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Stroker, If you do not have the Twist of The Wrist books and/or the videos I would recommend that you try to get them. You should be able to purchase them from the school's main site. http://www.superbikeschool.com/ and go to the store page. here https://secure.echoalley.com/superbikeschool/store/

 

If you look on Youtube you may be able to find the Twist videos there. That is provided that you can view them in your area.

 

Gymkhana is a sport where the basic riding rules apply. Some of the techniques are different from track riding though.

 

 

Jeff

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I was watching this Moto Gymkhana video and am trying to work this out -

 

They counter steer to weave in between the cones.But when they do U turns and circles, they are turning the bars right to go right and left to go left...?

 

Are they initiating the U turns and circles by countersteering and then turning the bars right to go right and left to go left...?

 

Help me understand this? Thanks

 

What you see is less evident for track or street riding: big changes of speed between maneuvers (from and to almost zero mph for the rear tire).

That makes countersteering minimum or non-existing.

 

Going into lean to go around the obstacle, yes, countersteering to initiate the rolling movement and then strong braking-steering that finishes the lean needed to keep balance around the cone.

 

Going out of lean leaving the obstacle, no, zero countersteering (as the steering has been locked against the end while rotating around the cone) to straighten the bike, just strong acceleration and steering.

 

Hope this helps you, but ............... you have brought your question to super-fast track riders who seldom ponder the mysteries of slow riding. :)

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Lnewqban it is interesting that you mention rear tire speed, would you care to elaborate on that statement?

I will disagree with the countersteering statement about minimum to non-exiting though and go back to my earlier question: At what speed would you not have to countersteer?

 

Hope this helps you, but ............... you have brought your question to super-fast track riders who seldom ponder the mysteries of slow riding. :)

Are there any differences between the two? If so, what are they?

 

Bonus question: What is the same between super fast track riders and Gymkhana riders?

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Lnewqban it is interesting that you mention rear tire speed, would you care to elaborate on that statement?

I will disagree with the countersteering statement about minimum to non-exiting though and go back to my earlier question: At what speed would you not have to countersteer?

 

Hope this helps you, but ............... you have brought your question to super-fast track riders who seldom ponder the mysteries of slow riding. :)

Are there any differences between the two? If so, what are they?

 

Bonus question: What is the same between super fast track riders and Gymkhana riders?

 

Yes, the extreme rotational maneuvers make the rear tire move much slower than the front tire.

Actually, the rider tries to complete the maneuver with the minimum possible trajectory of the rear tire, because trajectory has more influence on shortest attack times than speed.

 

It is not that there is a speed below which you wouldn’t have to counter-steer; the problem is that the rider cannot turn the handlebar anymore: the circle is completed at full lock due to the reason explained above.

 

Are there any differences between the two? – Yes:

- The magnitude of the angle of steering.

- Steering the bike at full lock by acceleration rather than by counter-steering.

- For one rider, speed is key; for the other, it is radius.

- One rider avoids max lean angle; the other induces max lean when at full lock (because that reduces the radius of turn).

 

What is the same between super fast track riders and Gymkhana riders? – Fine sense of balance. :)

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I just wasn't thinking about the wheel rotational speed difference between the fast front tire (Large radius) vs slow rotational speed rear wheel (short radius)

In otherwords I was having a Forest Gump moment "Stupid is as Stupid does" :o

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................ In otherwords I was having a Forest Gump moment "Stupid is as Stupid does" :o

 

No stupid at all, these things are difficult to see.

 

Cornering properly at the track means successfully dealing with the centripetal acceleration and its associated forces that try keeping us going straight instead of making a curve.

As we all know, those cornering forces depend on the square of the velocity and on the inverse of the radius.

 

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The radii of turns in the track are huge, which make us focus on velocity (any number elevated to square can grow or shrink fast); hence, the required fine senses of entry speed and throttle control.

In those conditions, when we need a rolling lateral force to change lean angle, we momentarily change the centripetal acceleration by changing the radius of the turn via counter-steering.

 

The radii of turns in the Gymkhana track are so small that become the main factor in the formula of centripetal force (any number divided by almost zero becomes almost infinite); hence, a little change in velocity gives enough rolling lateral force to come out of lean.

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Lnewqban it is interesting that you mention rear tire speed, would you care to elaborate on that statement?

 

I was interested in how you noticed the rear tire speed in the video. Therefore asking you to elaborate on that statement.

Your reply was/is spot on.

Hence my following reply along with my daft self poking statement because I was not thinking.

 

I just wasn't thinking about the wheel rotational speed difference between the fast front tire (Large radius) vs slow rotational speed rear wheel (short radius)

In otherwords I was having a Forest Gump moment "Stupid is as Stupid does" :o

I ride some Gymkhana locally and was not thinking about the physics required to preform the maneuvers while watching the videos.

 

I think that I may not be thinking right now :rolleyes:

 

You do require me to dig deep into the old grey matter with your mathematical equations and diagrams. It is stuff that I have not used on paper for 25+ years.

Keep 'em coming even if it is frustrating for me time to time trying to remember. I still enjoy working the brain.

 

Jeff

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