Resonance for motorcyclist? Tank slappers.

[wrtner]

.
If there is one thing that we know about it is resonance - the benefits and pitfalls. Have a look at this video, noting carefully at T= 0.55 secs:

https://www.youtube.com/watch?v=-k26h7XOpHo

Is this a resonance effect in a mechanical system?

If so, can we solve it for these petrol heads?
.

[Joit]

I think more its a problem from the damper and her distance, that they are not exact tie. Remember how a turning wheel usually stays stable in on Direction like a Spintop. There must be another Force what try to pull it back beside the hands at the handlebar. If you would have a direct control over the the linkage, the wheel would stay in the direction where it is brought to.

They need to check the sealings often from her dumpers or replace the whole dumpers oftens, that it got less space at the linkage.

[indio007]

.
If there is one thing that we know about it is resonance - the benefits and pitfalls. Have a look at this video, noting carefully at T= 0.55 secs:

https://www.youtube.com/watch?v=-k26h7XOpHo

Is this a resonance effect in a mechanical system?

If so, can we solve it for these petrol heads?
.

It's certainly a resonance effect in my opinion. A very complicated one to model because of the various directions of applied forces.

The hard part for me to figure out is the role the driver plays.
i.e. Would the handle bars still oscillate if he let go of the handle bars?

[ewizard]

It's natures way of eliminating showoff idiots that do wheelies in traffic.

For the more science based part I'd say the sudden startup to high speed generates a lateral torque that is trying to find a stable spot as it gains speed. The riders spring loaded arms resisting that to try to keep it centered result in the oscillation continuing. The solution is simple .... don't do wheelies.

BTW I'm not anti-motorcycle. I have one and ride too.

[dR-Green]

It's natures way of eliminating showoff idiots that do wheelies in traffic.

It can happen any time when both wheels are on the ground, I'm not a biker so I don't know what actually causes it, but I do have biker friends. Counter-intuitively the solution is to accelerate. Slowing down will cause a more violent oscillation and flip you right off. You could say that the energy is transferred into the side to side "amplitude" if the wavelength of the oscillation is not increased through acceleration.

[wrtner]

I wonder if we can produce an equivalent electronic tank circuit as a stepping stone to suggesting a remedy

What do you think of this scenario?

AC power supply:
As the wheel comes down and hits the road, there will be an oscillation depending upon the tyre pressure. This oscillation drives the resonant circuit.The frequency is a function of tyre pressure and the voltage will be a function of the speed with which the tyre hits the ground.

Inductor/capacitor:
The frame will have a "springiness", and a natural frequency. The frontforks will contribute in some way.

What else?

[Quigon10101]

The phenomenon seems to be significantly more pronounced with lighter weighing individuals. For example in the video they show a boy and a girl who experience dangerously violent tank slapping. Perhaps shifting the center of gravity forward can minimize tank slapping and make it more controllable. One way would be to shift the body weight forward by pressing down with your feet / trying to stand up while leaning forward your torso as the front wheel comes into contact with the road's surface. In other words, there must be a skill to minimize tank slapping and skilled bikers would know. Of course this would require a suitable and maintained suspension system adjusted to the weight of the bike and the person riding it.

Other things worth observing would be the design of motorbikes, their make / models specifically, to see if some of them are more prone to violent tank slapping than others. The second thing might be the tires specifications as well as the air pressure in them. Things like diameter and tire width and shape must be making a contribution to the overall effect. Last but not least, the braking system of bikes or the braking habits of the bikers more prone to tank slapping should be noted.

I think that with such simple but important skills and experience derived from such observations the problem should become easy to handle.

[dR-Green]

It's not a matter of wheelies or wheels hitting the ground.

Speed wobble - Wikipedia, the free encyclopedia