Zero Gyroscopic Bike 1

Zero-Gyroscopic Bike I -- A Fundamental Bicycle Experiment

Zero-Gyroscopic Bike I — A Fundamental Bicycle Experiment

Zero-Gyroscopic Bike I is a clever and yet simple experiment that dispels once and for all the centuries old conventional wisdom that a bike stays upright primarily due to the gyroscopic action of the two rotating tires.
The two additional or upper wheels are positioned on this bike so as to rest on the regular two lower wheels. Based on simple frictional contact between the two respective pairs of wheels, the upper wheels attain essentially equal but opposite rotation when forward motion of the bicycle is initiated. In the process of being ridden, the gyroscopic torques present and associated with spinning wheels will experience a precession cancellation effect whenever the bike rotates (yaws) or leans or when the front fork is turned. That is to say, the precession torques are still present and act on the frame and front fork assembly, respectively, however the double wheel pairs rotating in reverse directions to each other cause all precession torques associated with spinning action to be cancelled. In essence, this bicycle as configured can said to be a zero precession bicycle.
Because “precession” is an action, frequently lay people without sufficient technical background tend to become confused. The gyroscope on the other hand is a physical and familiar thing, so if we speak of gyroscopic action, the lay public tends to have a sense of what is being discussed. Hence, in many of our writings, as well as here, we will refer to bikes with precession canceling or even precession altering characteristics as “zero gyroscopic,” but we admit that this is technically in error. The action of a gyroscope can’t be made to equal zero. Newton’s Laws as well as conservation of angular momentum are stalwart pillars of classical science and mechanics. Instead, we do note that two gyroscopes can be designed to counter rotate on the same shaft or on parallel shafts so as to negate or cancel each other. The result is as if the combination of gyroscopic actions was “zero” but the gyroscopic action is only canceled out by clever design of opposing gyroscopic actions.
The empirical significance of Zero Gyroscopic Bike I is that the argument advocating sole dependence upon the “gyroscopic action” for stabilization of a bicycle is smashed and thrown out the window. Not only is the Zero Gyroscopic Bike I rideable, it is in fact, easily rideable. Hundreds of average persons, and even some fairly novice bicyclists, have ridden this bike. Other than being slightly heavier and bulkier due to the two additional wheels, this bike acts almost indistinguishable in handling as compared to a conventional bike.
Jones was the first, to our knowledge, to experimentally investigate precession cancellation as related to bicycles. We note, however, that UIUC Zero Gyroscopic Bike I, circa 1986, was the first to embody a technique that would cancel the gyroscopic torques at all operating speeds. Moreover, Zero Gyroscopic Bike I cancelled not only the front fork gyroscopic component, but also that associated with the rear tire. Of course, we routinely encounter ardent believers in the right hand rule who claim that our experiments are lacking in validity as the sprockets are still turning and even the legs of the rider, when pedaling, create the equivalent of a rotational gyroscope. Such arguments of desperation of this kind are easily silenced – merely by riding the Zero Gyroscopic Bike I in a coasting mode. Leg action ceases, and the sprockets and chain aren’t moving. The Gyroscopic Bike I is easily ridden while in the coasting mode.
In our archives, for those who doubt or those who just want fun, we have the written transcript of a lengthy interview with a fire and brimstone young Ph.D. in physics, an assistant professor of physics at a major Midwestern land grant university, circa 1985. The “professor” professed and defended the exclusive role of precession and gyroscopic action down to the last minutiae – in asserting that precession/gyroscopic alone was the sole mechanism responsible for keeping bicycles and motorcycles upright. He even went on to say that he’d bet $5 that UIUC Zero Gyroscopic Bike I, as proposed on paper the time of the interview, would be impossible to ride. He added, “Of course, unless one was a Chinese acrobat.” He would bet only the $5 amount as he said that he was too impoverished as a brand new PhD to bet more.
The only significant handling difference discovered in riding trials, compared to conventional bikes, was that the Zero-Gyroscopic Bike I was not capable of being ridden “no-hands.” We hypothesized that the additional front wheel, being extended in an upward and forward position, had caused the mass of the front fork assembly to be increased and also that the center-of-mass was shifted forward (as measured relative to the location of the steering axis). As a consequence, if the Zero-Gyroscopic Bike I were to go into a tilt, we reasoned that the action of gravity caused the front fork to turn excessively into the direction of tilt, and thus the bike was not rideable in the “no-hands” sense.

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