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Physics of steering


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My background is I know a bit about rotors (wheels) especially helicopter rotors and car / motorcycle wheels, and some physics in general. But, I am no professional. 

So, unicycles can be steered by a variety of means:

1) Hop and twist, usually with initial rotational acceleration low enough to be overcome by friction from the tire, continuing thru the inversion of the initial setup twist, and finally sent to the unicycle with a kick to alleviate the majority-static friction allow the rider's rotational inertia to reorient rider and cycle. This works mostly at very low speeds. The dynamics of the actual transfer may be slightly different than stated. 

2) Weight shift. Unbalance the unicycle in a given direction, and other things equal, you accelerate in that direction. Works laterally as well as back and forth.

3) Countersteer. In short, the lateral load to track a given radius increases disproportionately with speed (a square) while the sideways displacement of the lean-balanced vehicle increases much more slowly with speed. The result is that once you start moving a wheeled vehicle at any appreciable speed, the tendency to lean the vehicle opposite way the wheel is steered grows so much faster than the track in counter-steer direction that the counter-track becomes nearly imperceptible and the leaning tendency very great. This happens at only a few miles an hour. So, it is generally more appropriate to talk about an input torque for countersteering than a steer angle. A common apocrypha about countersteering is that it relies on gyro effect. It does not, for the reasons explained above, however, gyro effects are an additional and important component to steering lean-balanced vehicles and due to a phenomenon called precession they work to some extent in concert with countersteering. I say to some extent, because, being gyros, there is also a resistance to turning which from a maneuverability standpoint sucks.

4....) Ways I don't know about, or dumb and impractical ways like jet-reactive, aerodynamic, or magnetic devices. 

Obviously method number 3 is by far the most interesting because it gives us the most control of the unicycle at speed, where weight shift steering by itself may not give adequate response. I am trying to figure out what input the rider gives to make the simplest and most powerful counter-steer. From my extremely limited riding experience, it seems like weighting the outside pedal followed by a natural in-phase shift to inside weight is key. But, I don't know anything about riding these machines yet. 

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