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I A rider cornering at maximum g

  1. Dec 17, 2017 #1
    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?
     
  2. jcsd
  3. Dec 17, 2017 #2
    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.
     
  4. Dec 18, 2017 #3

    cjl

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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.
     
  5. Dec 18, 2017 #4

    berkeman

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    Staff: Mentor

    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.
    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.
     
    Last edited: Dec 18, 2017
  6. Dec 18, 2017 #5

    berkeman

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    Staff: Mentor

    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...



     
    Last edited: Dec 18, 2017
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