4 ms·

Well, yes. How 'high' the side is depends on many factors, but it's a gradient. A death wobble when going in a straight line happens to be relatively weak with

by hexaga 3y ago

Well, yes. How 'high' the side is depends on many factors, but it's a gradient. A death wobble when going in a straight line happens to be relatively weak with regard to how much force the rider is ejected with should it fully destabilize / lose contact w/ the road in either direction, but you still get ejected in the same way. As you increase wheel misalignment with the direction of travel (and speed), more energy goes into the fling. As you increase lean angle (more lean means more time for the wobble to accelerate you) the fling gets more violent on one side and less violent on the other (the 'high' and 'low' sides). Hence, the observation that high sides are what happens when you enter a death wobble that is already past the point of stability.

MarkMarine 3y ago
Do you have sources to prove this? I race motorcycles, I have a mechanical engineering degree and build race motorcycles, spent a lot of time researching motorcycle suspension dynamics to improve my systems and I think you’re basically making this up. We can chat about it more, but I’d like to see your sources so I can see what you’re basing this on.
- hexaga 3y ago
  Prove what, specifically? I'm honestly unsure which part is a controversial enough claim as to require sources. It seems trivial to me that in both cases a perpendicular force applied at the road acts to fling you, and that said force comes from wheel misalignment with the direction of travel. Is that not the case?
  - MarkMarine 3y ago
    Prove that the dynamic instability that causes a speed wobble is the same thing that causes a high side. Here is an article on the physics of wobble: https://en.wikipedia.org/wiki/Speed_wobble https://en.wikipedia.org/wiki/Speed_wobble A high side happens when the rear tire breaks traction at lean, and is no longer able to hold the arc it’s trying to turn on. The forces in the tire, suspension, twist and deflection in the swingarm and the frame of the motorcycle rapidly unload, and the bike turns around the z axis if x and y are the flat plane of the road surface. Then catches traction, and that z axis rotation and gyroscopic forces becomes a violent flick to stand the bike up straight. These things are totally different.
    - hexaga 3y ago
      > Prove that the dynamic instability that causes a speed wobble is the same thing that causes a high side. This is a broader claim than the one I made. > A high side happens when the rear tire breaks traction at lean, and is no longer able to hold the arc it’s trying to turn on. [...] Then catches traction, and that z axis rotation and gyroscopic forces becomes a violent flick to stand the bike up straight. How much lean? And how much traction loss / for how long? What if there's just enough to where a high side doesn't occur and the bike/rider don't fly off? Will the bike instantly right itself with no overshoot, without any sort of steering column oscillation? If there is an oscillatory response, what do you call it? What do you call it as you gradually reduce the lean angle to 0? At near 0 lean angle, is this oscillatory response meaningfully different from the oscillation of a speed wobble?

by hexaga 3y ago

MarkMarine 3y ago

Do you have sources to prove this? I race motorcycles, I have a mechanical engineering degree and build race motorcycles, spent a lot of time researching motorcycle suspension dynamics to improve my systems and I think you’re basically making this up. We can chat about it more, but I’d like to see your sources so I can see what you’re basing this on.

hexaga 3y ago
Prove what, specifically? I'm honestly unsure which part is a controversial enough claim as to require sources. It seems trivial to me that in both cases a perpendicular force applied at the road acts to fling you, and that said force comes from wheel misalignment with the direction of travel. Is that not the case?
- MarkMarine 3y ago
  Prove that the dynamic instability that causes a speed wobble is the same thing that causes a high side. Here is an article on the physics of wobble: https://en.wikipedia.org/wiki/Speed_wobble https://en.wikipedia.org/wiki/Speed_wobble A high side happens when the rear tire breaks traction at lean, and is no longer able to hold the arc it’s trying to turn on. The forces in the tire, suspension, twist and deflection in the swingarm and the frame of the motorcycle rapidly unload, and the bike turns around the z axis if x and y are the flat plane of the road surface. Then catches traction, and that z axis rotation and gyroscopic forces becomes a violent flick to stand the bike up straight. These things are totally different.
  - hexaga 3y ago
    > Prove that the dynamic instability that causes a speed wobble is the same thing that causes a high side. This is a broader claim than the one I made. > A high side happens when the rear tire breaks traction at lean, and is no longer able to hold the arc it’s trying to turn on. [...] Then catches traction, and that z axis rotation and gyroscopic forces becomes a violent flick to stand the bike up straight. How much lean? And how much traction loss / for how long? What if there's just enough to where a high side doesn't occur and the bike/rider don't fly off? Will the bike instantly right itself with no overshoot, without any sort of steering column oscillation? If there is an oscillatory response, what do you call it? What do you call it as you gradually reduce the lean angle to 0? At near 0 lean angle, is this oscillatory response meaningfully different from the oscillation of a speed wobble?