A rider cornering at maximum g

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Discussion Overview

The discussion revolves around the dynamics of a motorcycle rider cornering at maximum lateral acceleration, specifically focusing on the rider's actions to maintain grip and control. Participants explore the implications of pushing down with the knee versus countersteering, examining the effects on tire grip and cornering stability.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant suggests that pushing down with the knee might unload the tires and cause a loss of grip, similar to countersteering, while questioning whether the combined forces would mitigate this issue.
  • Another participant shares personal experience indicating that even a small shift in weight, such as touching the inside foot down, can lead to a loss of traction and a wipeout.
  • A different viewpoint argues that applying force with the knee decreases the normal force on the tire, which could lead to sliding and loss of control.
  • Some participants express skepticism about the effectiveness of using the knee for leverage during cornering, emphasizing that maintaining a consistent lean angle is crucial at maximum lateral acceleration.
  • One participant notes that while countersteering is essential, the dynamics of cornering change after the apex, allowing for adjustments in body position and steering technique.
  • There are references to professional riders' techniques, suggesting that some riders may employ different body movements during cornering, but the relevance to the discussion remains uncertain.

Areas of Agreement / Disagreement

Participants express differing opinions on the effectiveness and safety of pushing down with the knee while cornering. There is no consensus on whether this action is beneficial or detrimental to maintaining grip and control.

Contextual Notes

Some claims depend on specific riding styles and conditions, and the discussion does not resolve the complexities of tire dynamics and rider techniques in high-speed cornering.

Erunanethiel
The rider is cornering at maximum available lateral acceleration so he is not able to countersteer to the "inside" in order to bring the bike to the vertical position. So he decides to push down to the road with his knee to bring the bike up, does that unload the tires by countering gravity and cause him to lose grip just as he would if he countersteered? Or wouldn't it be a problem since combined vectors of centrifugal force and gravitational force are in line with the motorcycle and pushing with your knee to the ground doesn't cause a problem?
 
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I can tell you from personal experience with a recumbent bicycle that merely touching the inside foot down will unload the rear wheel enough to cause an instant wipeout. This particular recumbent would then end up sliding along with me perched on top. No scrapes (on me), no bruises. I did this several times before learning to keep my feet on the pedals and countersteer when it started to lose traction.
 
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This is a bad idea, since any force applied by the knee will decrease the normal force at the tire, causing it to be unable to support the lateral cornering loads. This causes the tire to slide, and as JRMichler said, it will cause the rider to wipe out.
 
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Erunanethiel said:
So he decides to push down to the road with his knee to bring the bike up
Have you tried doing anything with your knee during cornering at the racetrack, other than feeling your lean angle? It's not very reasonable to try to get any leverage or vertical travel with it to push yourself back up, IMO.
Erunanethiel said:
The rider is cornering at maximum available lateral acceleration so he is not able to countersteer to the "inside" in order to bring the bike to the vertical position.
Unless you get in trouble, you will not be changing your lean angle mid-corner at maximum lateral acceleration and traction. You only start to straighten up after the apex as you open up your turn radius and power out of the turn, so you have the flexibility to use an outside bar push (countersteering) or outside peg weighting (body steering) or both at that time.
 
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berkeman said:
It's not very reasonable to try to get any leverage or vertical travel with it to push yourself back up, IMO.
ADD -- Not withstanding Marc's antics in MotoGP saving slides...

ADD2 -- Valentino Rossi used to relax his legs like that going into turns too. I guess it's getting more common now...



 
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A bike, by design, "wants" to go straight. When cornering at the limit, you are constantly countersteering (push inside bar, pull outside), simply eliminating your countersteering will pick the bike back up.
You are already sliding at maximum cornering, pushing the outside bar and/or pulling the inside bar the amount needed to pick up from a corner is insignificant.
In a corner, taken properly, the front will have a bit more work to do until just before the apex, after that, the rear has a much higher load on it. (Hence the larger size)
 

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