Jump to content

Lnewqban

Members
  • Posts

    314
  • Joined

  • Last visited

  • Days Won

    13

Everything posted by Lnewqban

  1. You can have an exact idea by hanging off your bike while moving in a straight line rather than in a turn. By relocating the CG of your body away from the vertical line that goes down between the contact patches, you are relocating the CG of the bike alone away from the same line in the opposite direction. That last angle is what you are saving the bike from leaning in any turn.
  2. If your style works for you, why change it? You can learn it just as a safety margin for unexpected surprises in the street. If trying the hang off while turning takes you out of your comfort zone, you can practice with the bike going straight until it feels natural. Because it is a balance act, forces on your body and bike feel the same either turning or moving straight.
  3. That fear is logical, since the process of counter-steering and leaning is unbalancing in nature. However, you need to understand that the bike and yourself are not falling in, rather both are relocating to an angle of new and perfect balance (both are coming back from a "fall" into a more stable position). The reason is that the circular movement into which we commit, makes the "gravity forces" point non-vertically down, but towards one side and down (making the bike and yourself "heavier"). Think of the source of gravity under you shifting towards outside the curve while you travel into that curve. All we are doing is relocating the combined center of gravity "over" the line joining both tires' patches, so those "gravity forces" go through that line. For a constant turn radius, whenever we input steering movements during a curve, we are basically counter-steering and forcing the bike out of the "leaned" balance described above (disturbing the balance). Actually, that is the only way to come back to a vertical position (new balance state) once the circular trajectory ends and becomes linear. Think of the source of gravity pulling you shifting towards directly under the bike while you travel into that straight line (or shifting towards the opposite side in the middle of a chicane). Hope this helps
  4. The new diagram is exaggerated regarding angles and locations of centers of gravity, but shows the basic principle.
  5. I did fall this morning, when a van run a stop sign just in front of me. I had started the bank to turn in that corner when I saw the van coming to hit me if I wouldn't brake. Immediately survival reaction #7 took over my brain and, before I could blink, my hand was squeezing that front brake lever. Just on pure instinct I did in a turn what I do each day while moving in a straight line: gentle front brake without touching the rear brake. I guess my point is that survival reactions shut the conscious system down in a fraction of a second without asking permission. If I had had a conscious reaction, I would have straighten the bike up before applying the brake. My gear protected me but got no help from the van driver, who stopped, looked and continued without saying a word while I had the bike over my left leg.
  6. Not true I'm afraid. The amount of centripetal (cornering) force produced, as Hotfoot says, depends on the amount of weight and how far inwards (horizontally) it is of the contact patch. This varies with lean angle of course, and a tall bike will thus produce more of it than a short one at the same lean angle. If you watch the attached diagram with your head tilted to the right, you will see a bike rolling on one side of the tires, over an inclined road, and carrying a weight somehow higher than its natural weight (bike+rider). The leaned bike is balanced because all the forces go to ground through the tires, just like when it is traveling in a straight up position. When properly leaned in a turn, a motorcycle is as stable as when perfectly straight. The reason being that the weight of the bike plus the forces generated by the circular movement don't point vertically down but towards an angle between vertical and horizontal. Hence; the height at which the CG is located has no influence on the total (bike+rider) lean angle.
  7. The help comes from eliminating the braking effect of the engine. Sudden deceleration is what transfers a lot of weight from the rear tire onto the front tire; all bad for friction and suspension. Yes, I have been trying to reduce the danger of rolling the throttle off while I learn to keep it on in panic situations. I have noticed that keeping two fingers on the front brake lever makes the undesired sudden roll-off of the throttle more difficult. Deceleration will always straight the bike up naturally.....if we don't lock the steering bar.
  8. As a street rider, I have been working on the persistent SR 1 a lot, and can tell that it is hard to eliminate, since it is a natural reflex many times initiated by sudden traffic conditions. As a way to reduce the braking effect of the sudden roll-off, I have been training my reflexes for combining the roll-off with a simultaneous clutch-in. That liberates the rear wheel and allows the front brake to take control over the (more gradually) deceleration of the bike while I stand the bike up from any lean (as much as possible). Very good questions, Chipset
  9. That makes the leaning angle not directly proportional with the speed of the bike. That means that between 20 and 30 degrees accommodates a wider range of speeds than between 30 and 40 degrees. At 45 degrees, the horizontal force pushing the tires is equal to the combined weight of bike and rider. If not acceleration is happening, around 40% of that force tries to skid the front tire and 60% the rear tire.
  10. Those are the same people not wanting to have chicken strips in their tires
  11. Hello everyone! The school is too far for me, but I have just joined to learn from you all. I have been a full time street rider since 1978 (started in Cuba, where I am from). Now I live in South Florida and I love discussing the physics and mechanics of motorcycles. After all those years of riding and repairing bikes, I believed I had accumulated much knowledge (mainly for surviving on the streets). Well, Keith's books and the DVD have proven to me that that knowledge of mine was not much at all. Although I will never probably be on a track, I like the California Superbike School; therefore, I will enjoy the discussions in the Forum. I'll see you at there.
×
×
  • Create New...