Precession and Gyroscope Issues

Precession is a scientific word that describes how a spinning wheel reacts if the axis is tipped or rotated in space. Given a tip in the axis of spin, the spinning wheel will exhibit precession meaning that the axis will tend to want to tip in a direction 90 degrees to the initial axis tip. Moreover, the direction of tip is dictated by what physicists and experts in mechanics refer to as the right-hand-rule. This tendency to exhibit precession has to do with the principle of conservation of angular momentum. In lay terms, it means that any spinning object has gyroscopic tendencies, and that the object is more stable about its spinning axis, and yet if forced to tip or deviate, then precession will cause an action in a direction 90 degrees to the initial axis.
Scientists and experts elsewhere have made similar claims regarding how the bicycle is critically dependent upon gyroscopic principles and the right-hand rule so as to remain upright, but we’ll defer from going down that path in the interests of brevity. We will mention experiments to be described later, specifically involving Rear Steered Bicycle I. If gyroscopic arguments constituted the primary stabilization mechanism for a bicycle, then it would appear to matter little if the bicycle was steered by the front wheel, or the rear wheel. The experimental record reveals evidence quite the contrary. Rear Steered Bicycle I has a nearly 20 year history of defying being ridden successfully in spite of exhaustive attempts, in cases including some skilled would-be riders.
A predictable outcome of somebody “scientific” explaining or demonstrating precession with the aid of a weighted wheel and a rotating stool or platform, is to be prone to conclude by saying, “And this is why a bicycle works.” Unfortunately, this scenario is more common than not among high school and university level physics instructors, as many teaching schools have access to a weighted bicycle tire capable of being spun on an axis (a handle), as well as a precision stool for the demonstrator to sit on while holding the spinning wheel, or possibly a rotating platform on which to stand. We state that the wheel used in these “demonstrations” is usually (and unfairly) weighted as the tire used is constructed of solid rubber, and thus with greater mass than, say, a conventional pneumatic tire. A central problem is that these “scientists” failed to do one thing – to test the conjecture or hypothesis with an actual experiment involving a complete bicycle, and where some type of valid control was devised to test the hypothesis.
An English chemist, Dr. David Jones, in the late 1960’s, performed an array of simple bicycle experiments, published in Physics Today on April 1st (Jones, 1970). A dominant feature of one of Jones’ experimental bikes was that he mounted an auxiliary spinning wheel on a bicycle’s front fork that was able to spin clear of the ground. Jones could spin the wheel in either direction and at various speeds, and yet the bike was discovered to be still rideable and independent of the resulting angular momentum magnitudes. Aside from the publication date being April Fool’s Day, Jones went on to shock the world of bicycle and physics aficionados by making several points: (1) In spite of Jones’ efforts to cancel or alter precession and thus gyroscopic action, Jones’ experimental bikes, and in all variations tested, were quite capable of being ridden. (2) Jones sought to discover how to design and build an unrideable bike, but he failed in that quest.
Dr. Richard P. Feynman (1918-1988), Nobel laureate of physics fame made the statement (paraphrased) – “Experiment is the ultimate authority.” In keeping with this spirit, Dr. Richard Klein initiated a number of bicycle related experiments in conjunction with students at the University of Illinois at Urbana-Champaign (UIUC), Department of Mechanical and Industrial Engineering, starting in 1983. Some these UIUC experimental bikes and conclusions are described below.

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