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#62
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"The Stability of the Bicycle"
writes:
Simon Brooke writes: 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...' There is one of the glaring failures of this report. There is mention of riding no-hands mixed in with being able to control the bicycle. In the above paragraph, one might assume he meant riding no-hands, but in fact that is impossible and was not the case. Therefore, it does not conflict with what I have said. On the contrary he is quoted as explicitly saying he rode no hands. See for example URL: http://www.dclxvi.org/chunk/tech/trail/ '...he found it difficult (although not impossible) to ride with his hands off of the handlebars ...' Dr Jones article is cited as Jones, David E.H., "The Stability of the Bicycle", Physics Today (April 1970): 34-40 I have not read it myself. -- (Simon Brooke) http://www.jasmine.org.uk/~simon/ ;; in faecibus sapiens rheum propagabit |
#63
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"The Stability of the Bicycle"
wrote in message ...
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 Dear Jobst, Perhaps we should drop that dreadful terminal "s" and speak of the Mathematic Department? After all, our fortunate, realistic children have led the way--they do arithmetic instead of arithmetics. When they grow up, let them study linguistic and and physic in the art and science. Wouldn't it have been easier to say oops, you didn't know that "maths" is proper slang where Brytysh bycyclysts named Smythe ryde on tyres? Nothing looks sillier than a pedant trying not to look ignorant--except, come to think of it, a pack of other pedants gleefully piling on top of him. Adult, n. A mature individual whose slightest lapse entitles everyone--including himself--to behave as childishly as possible. One who no longer enjoys the kindness and courtesy traditionally extended to children. Carl Fogel P.S. As a minor linguistic aside, plurals in English are historically troublesome. Consider the classic cases of the pair of scissors and the pair of pants. We avoid dealing with their ambiguity by saying "gimme the scissors" or "hand me my pants, dear." The indefinite "the" and the innumerate possessive "my" gracefully avoid the vexed question of whether the scissors and pants are singular or plural. Well-educated snots will crisply ask for "a scissors," loftily informing anyone who cares that the instrument is singular. They then wonder why the snips are handed to them point-first. They never ask for "a pants." In Old English (not Chaucer's fairly readable Middle English), the pants and scissors were no problem at all. The world was "sensibly" divided into not singular versus more than one, but into singular, dual, and more than two. They had words like "a" for things came one by one, words like "those" for things that might come in droves, and words in-between that we now lack for things like pants, scissors, and portions of the human anatomy that naturally come in pairs. Like the British "maths," a singular-dual-plural system is obviously wrong and reprehensible to us, but makes sense to those who know no better. The Old English also cared about gender and divided almost everything into masculine and feminine. This was too damned complicated, so English lost almost all gender, just as today there is a growing tendency among European youths to forgo the proper masculine and feminine articles. Only the strong survive, so most of our words have been simplified and regularized. Our strongest words are the most common verbs, used in most conversation. Feeble modern verbs like bicycle are quite simple: bicycle, bicycles, bicycled, and bicycling. There is no "bicycleth," much to Jobst's relief (although "Jobst's" is easier to type than to pronounce). The strong verb in English is the hideous hodge-podge "to be," which is conjugated as am, is, are, been, being, was, and were, a completely nonsensical progression explained by the fact that we once had several forms of "to be" with different meanings that all got mashed together in the continuing bumper-car madness of linguistic evolution. (Consider Spanish, where "ser" and "estar" both translate to "to be," but have important differences obvious to any child brought up in the language.) C.F. P.P.S. Double-dare ya' all to top this for linguistic pedantry! C.F. |
#64
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"The Stability of the Bicycle"
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#65
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"The Stability of the Bicycle"
I asked a simple question about the relative effect of the two.
Check the equations on my web site http://www.calpoly.edu/~wpatters/ Most bikes have little moment of inertia on the front wheel. Therefore, the torque trasmitted up the steer tube is small. The primary torque coming up the steering column is from the vertical normal force and sideward friction force on the front wheel contact point. These forces generate a torque acting through the trail vector that is then dot producted (?) with a vector up the steer tube. Motorcycles and bikes with heavy rims are exceptions. In my opinion, stability is not a suitable design goal. No fighter aircarft was designed to be stable. The airplane guys started "doing" stability when they started flying instruments and didn't have good situational awareness. You don't want a stable bike. You want a bike the responds properly to your intentions. |
#66
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"The Stability of the Bicycle"
Simon Brooke wrote:
writes: Simon Brooke writes: 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...' There is one of the glaring failures of this report. There is mention of riding no-hands mixed in with being able to control the bicycle. In the above paragraph, one might assume he meant riding no-hands, but in fact that is impossible and was not the case. Therefore, it does not conflict with what I have said. On the contrary he is quoted as explicitly saying he rode no hands. See for example URL: http://www.dclxvi.org/chunk/tech/trail/ '...he found it difficult (although not impossible) to ride with his hands off of the handlebars ...' Dr Jones article is cited as Jones, David E.H., "The Stability of the Bicycle", Physics Today (April 1970): 34-40 I have not read it myself. Here's the relevant quote from the paper: ,---- | Gingerly, and with great trepidation, I tried the experiment -- | downhill, to avoid complicating the effort with pedalling. URB I is not | an easy bicycle to ride "hands off" even with the front wheel static; it | somehow lacks balance and responsiveness. In the disrotatory mode it was | almost impossible and invited continual disaster, but it could, just, be | done. `---- -- Benjamin Lewis Now is the time for all good men to come to. -- Walt Kelly |
#67
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"The Stability of the Bicycle"
(Carl Fogel) writes:
P.P.S. Double-dare ya' all to top this for linguistic pedantry! ITYMHM '_I_ _challenge_ _you_ to _better_ this for linguistic pedantry'. The phrase 'you all' is a deprected colonial form; the 'all is redundent and may be elided. 'Double-dare' is slang, and, worse, vulgar. Yours very sincerely, Simon Brooke esquire, metapedant. -- (Simon Brooke) http://www.jasmine.org.uk/~simon/ ;; in faecibus sapiens rheum propagabit |
#68
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"The Stability of the Bicycle"
On Thu, 09 Oct 2003 00:05:16 GMT, Simon Brooke esquire, metapedant
wrote: P.P.S. Double-dare ya' all to top this for linguistic pedantry! ITYMHM '_I_ _challenge_ _you_ to _better_ this for linguistic pedantry'. The phrase 'you all' is a deprected colonial form; the 'all is redundent and may be elided. 'Double-dare' is slang, and, worse, vulgar. Your spellchecker is broke. "Quis custodiet ipsos custodes?" - Juvenal ------------------------------- John Dacey Business Cycles, Miami, Florida http://www.businesscycles.com Now in our twenty-first year. Our catalog of track equipment: eighth year online ------------------------------- |
#69
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"The Stability of the Bicycle"
In article . net,
"Bill Patterson" wrote: In my opinion, stability is not a suitable design goal. No fighter aircarft was designed to be stable. The airplane guys started "doing" stability when they started flying instruments and didn't have good situational awareness. You don't want a stable bike. You want a bike the responds properly to your intentions. "Properly" in this case is probably what most of us are thinking of as "stable." In Jones's URB experiments, he was able to make a bike so stable that it was effectively unrideable- indeed it was so stable that it was self-balancing. The video that was broadcast in the two-part PBS show called "The Bicycle" about 10 years ago was very entertaining, with the riderless bike coasting away down a hill quite nicely. Conversely it's possible to make a bike so "responsive" that it's unrideable. Bikes for different purposes tend to need different stability characteristics. A "crit" bike tends to be very responsive, but after riding it 250 km it would be unpleasant. A bike designed for brevets and similar ultra-long rides will be very stable, to allow it to be ridden in a straight line while very fatigued, but wouldn't be much fun in a crit. My most stable bike is my track bike, despite the 75 degree head angle. It can be ridden no-handed very easily for long distances, around corners, up and down hill, over bumps, etc. That makes sense, since track bikes are effectively ridden in a straight line around a velodrome, thanks to the banking. My least stable bike is a mid-80's Japanese bike with a 73 degree head angle and a bit too much fork offset, reducing trail just a bit too much. |
#70
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"The Stability of the Bicycle"
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