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"The Stability of the Bicycle"
There was an article in "Physics Today" for 1970, 23(4), pp. 34-40 by David
E. Jones entitled, "The Stability of the Bicycle". I am trying to get a copy. Is it, perhaps, somewhere on the internet? Advice appreciated. Gerry |
#2
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"The Stability of the Bicycle"
"GerryK" wrote in message
news:vDOfb.7971$La.17@fed1read02... There was an article in "Physics Today" for 1970, 23(4), pp. 34-40 by David E. Jones entitled, "The Stability of the Bicycle". I am trying to get a copy. Is it, perhaps, somewhere on the internet? Advice appreciated. Google is your huckleberry. |
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"The Stability of the Bicycle"
http://ist-socrates.berkeley.edu/~fa...es/JonesBikeBW.
C.Q.C. "GerryK" wrote in message news:vDOfb.7971$La.17@fed1read02... There was an article in "Physics Today" for 1970, 23(4), pp. 34-40 by David E. Jones entitled, "The Stability of the Bicycle". I am trying to get a copy. Is it, perhaps, somewhere on the internet? Advice appreciated. Gerry |
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"The Stability of the Bicycle"
Sorry, for some reason that link didn't come out right when I posted.
You can get it from he http://socrates.berkeley.edu/~fajans.../bicycles.html And google was the way I found it. I read it last night, it is a great article. C.Q.C. "Q." wrote in message news http://ist-socrates.berkeley.edu/~fa...es/JonesBikeBW. C.Q.C. "GerryK" wrote in message news:vDOfb.7971$La.17@fed1read02... There was an article in "Physics Today" for 1970, 23(4), pp. 34-40 by David E. Jones entitled, "The Stability of the Bicycle". I am trying to get a copy. Is it, perhaps, somewhere on the internet? Advice appreciated. Gerry |
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"The Stability of the Bicycle"
anonymous writes:
http://socrates.berkeley.edu/~fajans.../bicycles.html or: http://tinyurl.com/pswa I read it last night, it is a great article. I can't imagine you read all that because it wallows around endlessly in unclear descriptions of what was tried and what results he got. For instance, try to find whether the bicycle with a counter-rotation wheel next to the front wheel was controllable riding no-hands and how it was different. I read that part several times and am still unclear about what he found. There are a few simple tests that he didn't do, one of which is to wheel the bicycle along a walking speed holding on to the saddle only. Most bicyclists have done this and those who were interested will note that it works by gyroscopic force and not working at all with no wheel rotation. It is this kind of omission and the wandering prose that give this report minimal credibility for me. Jobst Brandt |
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"The Stability of the Bicycle"
"Simon Brooke" wrote in message . uk... writes: There are a few simple tests that he didn't do, one of which is to wheel the bicycle along a walking speed holding on to the saddle only. Most bicyclists have done this and those who were interested will note that it works by gyroscopic force and not working at all with no wheel rotation. Uhhhmmmm... I habitually wheel bicycles with one hand on the saddle. I've always assumed that this worked in exactly the same way as riding a bike - i.e. lean to steer. Although I agree that in principle a rotating wheel has a gyroscopic effect at whatever speed it's rotating (and a fast spinning wheel a considerable one) I don't believe that there's much gyroscopic effect at this speed. Indeed, this seems to me to be borne out by the fact that one of my bikes which has a noticable tendency to pull left[1] can be wheeled quite happily one hand on the saddle - but only if tilted slightly right. However I haven't done the maths and am just going on perceptions. Has anyone done the maths for this? The greater mass of the wheel, handlebars etc. forward of the steering axis compared to the rear of the steering axis is the reason for the low speed steering when wheeling and leaning a bicycle. This is the case when the bicycle is stationary also. Gyro forces do not become dominant until much greater speeds. Phil Holman |
#8
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"The Stability of the Bicycle"
Simon Brooke writes:
There are a few simple tests that he didn't do, one of which is to wheel the bicycle along a walking speed holding on to the saddle only. Most bicyclists have done this and those who were interested will note that it works by gyroscopic force and not working at all with no wheel rotation. Uhhhmmmm... I habitually wheel bicycles with one hand on the saddle. I've always assumed that this worked in exactly the same way as riding a bike - i.e. lean to steer. Although I agree that in principle a rotating wheel has a gyroscopic effect at whatever speed it's rotating (and a fast spinning wheel a considerable one) I don't believe that there's much gyroscopic effect at this speed. 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. You don't need to solve differential equations. Indeed, this seems to me to be borne out by the fact that one of my bikes which has a noticeable tendency to pull left[1] can be wheeled quite happily one hand on the saddle - but only if tilted slightly right. That puts the required bias into it but steering is done by gyroscopic forces, trail taking care of the lean offset. However I haven't done the maths and am just going on perceptions. Has anyone done the maths for this? Don't! There is more to be gained by intelligent observation of natural phenomena. Jobst Brandt |
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"The Stability of the Bicycle"
jobst brandt wrote:
anonymous writes: http://socrates.berkeley.edu/~fajans.../bicycles.html or: http://tinyurl.com/pswa I read it last night, it is a great article. I can't imagine you read all that because it wallows around endlessly in unclear descriptions of what was tried and what results he got. For instance, try to find whether the bicycle with a counter-rotation wheel next to the front wheel was controllable riding no-hands and how it was different. I read that part several times and am still unclear about what he found. ,---- | 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 "Love is a snowmobile racing across the tundra and then suddenly it flips over, pinning you underneath. At night, the ice weasels come." --Matt Groening |
#10
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"The Stability of the Bicycle"
I can't bear to read this whole thread but I fear Jobst has pushe the
gyroscopec effect a bit far. Has he read The great Timoshenko's work on bicycle stability? This is a good read: http://www.bsn.com/Cycling/articles/dynamics.doc In conclusion, we have experimentally measured the dynamics of a bicycle under no-hands riding conditions and found reasonable agreement with a simplified set of equations of motion. The magnitude of the individual torques that cause the front wheel to turn in response to the frame leaning have been calculated. At higher riding speeds, the gyroscopic torque dominates over the torque caused by the rider's weight. Although the gyroscopic torque strongly affects bicycle dynamics above about 10 m.p.h., we cannot say to what extent it actually helps balance the bike. |
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