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#41
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"The Stability of the Bicycle"
wrote:
Simon Brooke writes: Well, just so. I agree that you can get strong gyroscopic effects with a fast rotating wheel, but I'm completely unpersuaded that they are significant at walking speed. So, again, has anyone done the maths? There are no "maths", math is an aggregate concept and has no plural... except in GB maybe. Simon is using British English correctly. "math" is not a word in the UK. -- David Damerell Kill the tomato! |
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#42
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"The Stability of the Bicycle"
yes or no: does a gyro react at 90 degress to an applied force or not?
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#43
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"The Stability of the Bicycle"
In article ,
jim beam wrote: yes or no: does a gyro react at 90 degress to an applied force or not? An applied force along which axis? |
#44
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"The Stability of the Bicycle"
I'm confused, but here's my train of thought. No one has mentioned
riding the rollers. -One potentially illuminating experiment is riding the rollers with no hands and a (too) tight headset. But, riding the rollers with no hands.... The faster I go the easier it is to stay upright. colloquially, I would say that I remain upright due to the gyroscopic mumbo-jumbo of the wheels and that I remain centered on the rollers by moving my weight to one side or the other (knowing that my bike will follow). With no hands, is my movement back to the center of the rollers be preceded by counter-steering by making the front wheel "flop" on way or another with some hip motion? I'm not sure. ..an obvious but unmentioned observation: at very low speeds on the rollers, steering occurs more via turning the bars and less via leaning--counter to the example of walking a bike with the hand on the saddle. (the reason for this is clear but how either of these extremes relate to the actual riding of a bike on the road is less clear to me). Finally, I think there's something to think about with riding the rollers on a bike with wheels that have twice the rotational mass. Easier or harder to: 1)stay upright and 2)stay centered on the rollers. I'm not sure. |
#45
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"The Stability of the Bicycle"
jim beam wrote:
as Jobst has claimed. that's proof? Proof of what? What are you talking about? You appear to be inventing straw men to knock down. Why don't have a look at what Jobst's actual position is: http://draco.acs.uci.edu/rbfaq/FAQ/9.35.html -- Benjamin Lewis Seeing is deceiving. It's eating that's believing. -- James Thurber |
#47
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"The Stability of the Bicycle"
Ian L? writes:
There are no "maths", math is an aggregate concept and has no plural... except in GB maybe. I guess you don't have a bicycle with a QR front wheel so you can't perform the simple experiment of turning the wheel at "walking speed" to fell the strong gyroscopic effect caused by tilting the wheel manually to the left and right. Sorry Jobst - we don't have "math" downunder either, we have "maths" as in Pure Maths, Applied Maths. "math" is an Americanism. That's fine. Only one with a stiff upper lip would create such an abbreviation that defies pronunciation. I suppose as long as it remains on the KBD it doesn't tangle the tongue. The essence of a lisp is the mix of 'th" and 's'. To make 'maths' from 'mathematics' is an excessive linguistic rigourosity. I see we are more fortunate in the USA with a bit of realism and where we do our 'math' without linguistic twisting of the tongue. Jobst Brandt |
#48
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"The Stability of the Bicycle"
"Simon Brooke" wrote in message . uk... Peter writes: jim beam wrote: Take the wheel out, spin it in you hands and try to tilt it to the left or right and note the force of the steering action. This should convince you of its effect. please explain. gyro reaction is _90 degrees to the applied force_. i.e. my front wheel, spinning "forwards" tries to tilt top rightwards when turned to the left. you seem to be implying that gyro recation is responsible for banking the bike to the left when steered left. No, when you wheel the bike along holding onto the seat you steer by banking the bike and the turn is a reaction to the bank. Banking the bike to the left will tend to initiate a turn to the left. But the gyroscopic force is quite small when the wheel is spun at only walking speed and the geometry of the bike also results in the wheel turning left in response to a left bank (even when the wheel isn't rotating). Well, just so. I agree that you can get strong gyroscopic effects with a fast rotating wheel, but I'm completely unpersuaded that they are significant at walking speed. So, again, has anyone done the maths? http://scienceworld.wolfram.com/phys...recession.html Phil Holman |
#49
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"The Stability of the Bicycle"
writes:
Simon Brooke writes: This isn't to deny that gyroscopic effects play some part, nor that the influence of gyroscopic effects increases with speed; but without some maths I'm skeptical about their being significant as compared to lean. Well don't just sit there and fret about it, try it. Take the wheel out and turn it. I've done that often enough. I'm aware of the degree of gyroscopic force you can get from a fast spinning wheel; all I'm questioning is how much this force contributes to balancing a bike, and whether it's a significant component (particularly at low speeds). The fact that bikes lean steer is easily verified; the extent to which this is gyro-assisted is less easily assessed. Does anyone have any figures? -- (Simon Brooke) http://www.jasmine.org.uk/~simon/ ;; how did we conclude that a ****ing cartoon mouse is deserving ;; of 90+ years of protection, but a cure for cancer, only 14? -- user 'Tackhead', in /. discussion of copyright law, 22/05/02 |
#50
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"The Stability of the Bicycle"
David Damerell writes:
"jim beam" wrote: Benjamin Lewis: "jim beam" as Jobst has claimed. that's proof? There's a neat piece of selective quoting. What this should read is; old high school physics footage of a bike being ridden with a counter gyroscopic wheelset. works just fine. And is reportedly "almost impossible" to ride no-hands, as Jobst has claimed. I.e., the behaviour of this bike substantiates Jobst's claim. With respect, that behaviour of a counter-gyroscopic bike is reported in Jobst's claim. Thus it can't either substantiate or refute it. What could substantiate or refute it is an independent report from someone who had either seen the film (in which case they could confirm what was said on the film) or had ridden the bike (in which case they could confirm the behaviour of the bike). Actually, this report URL: http://www.geocities.com/CollegePark...32/pyfair.html contradicts Jobst. It says that 'He reversed the front fork to nullify the caster action, and he fitted a counter-rotating wheel on the front fork to effectively nullify or cancel out the gyroscopic effects. When he was finished, he still found that the bicycle could still be balanced and steered quite easily... These experiments effectively disproved the hypothesis that gyroscopic motion was the primary force responsible for balance in a bicycle...' Now, I have no way immediately of assessing whether Jobst's claim or the report given above should be given more credence. But lean steer works for a number of other 'vehicles' which have no gyroscopic effects. Snowboarders manage just fine no hands, as do surfers. Furthermore, on both these platforms control increases with speed. Thus gyroscopic effects are not _required_ to account for the ability to ride a bike no hands. -- (Simon Brooke) http://www.jasmine.org.uk/~simon/ ;; how did we conclude that a ****ing cartoon mouse is deserving ;; of 90+ years of protection, but a cure for cancer, only 14? -- user 'Tackhead', in /. discussion of copyright law, 22/05/02 |
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