DrTriKat wrote:As some of the posts above state correctly, this can happen to any bike, any rider, any speed. The correct physics (scientific) term for this is resonance, and its defined as
vibrational motion at an object's natural frequency
when a person hits, strikes, strums, plucks or somehow disturbs the object. Each natural frequency of the object is associated with one of the many standing wave patterns by which that object could vibrate. It is the same phenomenon that caused the collapse of the Tacoma Narrows bridge. This happened to me once during a choral performance, when all 120 or so of us stood up on the risers at the same time (and apparently at just the correct "wobble" frequency) - the risers started swaying larger and larger amplitude. We then all moved at different frequencies upon the risers, and it did dampen and stopped after several agonizing seconds. But it could have brought us down easily. Those unaware of the laws of physics were unfazed. I was terrified.
Just so everyone does not get some aeroelastic engineer upset, the Tacoma Narrows bridge failure is not an example of resonance. It is an example of flutter. High speed wobble is a similar phenomenon, in that it is not due to resonance of natural frequency, if it was the magnitude would be reduced as speed increase or that it would not always occur at the same speed. Just think a road with bumps that are spaced at half distance to the road you experienced high speed wobble, if it was resonance on this road you would experience high speed wobble at half of the speed. http://velonews.competitor.com/...-speed-shimmy_309601
. The real take away is the high speed wobble is self exciting.
The good news is that solution is similar to a resonance problem, change the stiffness.