Motorcycle physics -- Countersteering and Bodysteering

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    Motorcycle Physics
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Discussion Overview

The discussion revolves around the mechanics of motorcycle steering, specifically focusing on countersteering and bodysteering techniques. Participants explore the implications of rider weight shifts on motorcycle handling, particularly in the context of real-world riding scenarios versus theoretical models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether a rider can change the combined center of gravity of the motorcycle system by shifting their weight, particularly in the context of a frictionless scenario versus real-world conditions.
  • Another participant asserts that using shifted weight on footpegs and the seat can initiate a lean in the motorcycle, suggesting that bodysteering can be effective despite the common reliance on countersteering.
  • Concerns are raised about the practical challenges of countersteering, especially in emergency situations where rider tension may hinder effective steering.
  • Participants discuss the limitations of bodysteering compared to countersteering, with one noting that bodysteering may not be as fast or effective as direct countersteering, referencing a specific video demonstration.
  • Historical context regarding the evolution of motorcycle riding styles is introduced, linking it to the discussion of bodysteering techniques.
  • One participant shares a video of a "no BS" bike, suggesting that its design may limit the effectiveness of bodysteering, while also noting the rider's difficulties in weight shifting during the demonstration.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of bodysteering versus countersteering, with no consensus reached on which method is superior or under what conditions each is preferable. The discussion remains unresolved regarding the implications of rider weight shifts on motorcycle dynamics.

Contextual Notes

Participants acknowledge the influence of various factors such as tire friction, bike geometry, and rider behavior on steering effectiveness, but these aspects remain complex and not fully resolved within the discussion.

  • #61
rcgldr said:
I don't think there is a reliable way to do this. Again, using the bike on a tight wire comparison, the long balance pole weighs more than the bike, in order to maintain balance on such a system.
As long as there is friction between the road and tires, it is very unlikely that bike's movement will completely cancel out rider's movement one way or the other, the hard but I think is which way that will be
 
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  • #62
rcgldr said:
I don't think there is a reliable way to do this. Again, using the bike on a tight wire comparison, the long balance pole weighs more than the bike, in order to maintain balance on such a system.

Erunanethiel said:
As long as there is friction between the road and tires, it is very unlikely that bike's movement will completely cancel out rider's movement one way or the other, the hard but I think is which way that will be
What I meant is that the rider ends up leaning the wrong way after the initial application of force. However, once gravity takes over and causes the system to continue to fall, the rider can then lean the correct way since that won't prevent the system form continuing to fall.
 
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  • #63
rcgldr said:
What I meant is that the rider ends up leaning the wrong way after the initial application of force. However, once gravity takes over and causes the system to continue to fall, the rider can then lean the correct way since that won't prevent the system form continuing to fall.
Oh what you said is there is not a reliable way to push the bike and then the rider ending up leaning the same way the system is turning to right? The rider can shift his weight to offset the center of mass of the system horizontally with a bike with no trail, but he would end up leaning the wrong way is what you are saying, have I got it right?
 
  • #64
Erunanethiel said:
Oh what you said is there is not a reliable way to push the bike and then the rider ending up leaning the same way the system is turning to right? The rider can shift his weight to offset the center of mass of the system horizontally with a bike with no trail, but he would end up leaning the wrong way is what you are saying, have I got it right?
The rider initially ends up leaning the wrong way, but once the system is leaning, then gravity becomes the dominant factor, and the rider can then lean the correct way, since the rider's movements won't be enough to prevent the system from continuing to fall over, at which point steering inputs will be needed.
 
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  • #65
rcgldr said:
The rider initially ends up leaning the wrong way, but once the system is leaning, then gravity becomes the dominant factor, and the rider can then lean the correct way, since the rider's movements won't be enough to prevent the system from continuing to fall over, at which point steering inputs will be needed.
So the bottom line on this thread is that, it is possible to change the horizontal position of the center of mass of the system with body weight shifts on a bike with no trail geometry, but you would need to "catch" the bike through handlebar inputs to stop the bike from falling. I guess if you confirm what I said is the case, we can call it done!
 
  • #66
Erunanethiel said:
So the bottom line on this thread is that, it is possible to change the horizontal position of the center of mass of the system with body weight shifts on a bike with no trail geometry, but you would need to "catch" the bike through handlebar inputs to stop the bike from falling. I guess if you confirm what I said is the case, we can call it done!
Correct.
 
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