h a l f b a k e r yNot so much a thought experiment as a single neuron misfire.
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Changing the angle could create a gear-like transmission effect. If the tires are spokeless and hubless in the middle, like in {linky}
they could be set one within the other.
You gain bigger wheels at same hight of ride.
hubless spokeless wheel
http://www.wipo.int...o.jsp?wo=2006131742
wheel with no spokes and no hub invention. [pashute, Mar 31 2008]
Sea-Bow disc wheels
http://www.sea-bow....bow/photo/New01.jpg
Like this? Notice that there are normal wheels also. [baconbrain, Mar 31 2008]
[link]
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I'm all for brevity - but this makes no sense. |
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Could you go into a bit more detail so I can understand this? |
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Wouldn't that tend to yaw the bicycle in the direction the wheels were tilted? (Just thinking from when I've played with tilting bikes at extreme angles: they tend to want to go in circles.) |
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Yeah, unless it is a point contact, you are going to get yaw effects. |
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There was a powered-parachute cart that used dome/dish wheels with a nearly-vertical axle. I'll see if I can find it. (link) |
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I'm not liking this at all. Not understanding it, really. [ ] |
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There was once a British-designed turtle-like (in the Logo language sense) plotter that used a canted wheel arrangement in the early 1980s. Can't remember the advantage, apart from reduced height. |
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I'm not seeing how you could pull off the //set one within the other// part. If the hubless wheels were anything like the one in the link, then you would have to have a seperate drive mechanism for each wheel. Even if the drive mechanism was vertically off-set so as not to get in the whay of the other wheel, they would all have to be connected to the pedal sprocket. They would all, also have to be rigidly connected, but this wouldn't allow for the articulation each would need to be projected down further than the others (for the inner wheels to make contact with the road). And as for the angle; what Dr.Curry and Mr.QED said. |
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Friction ... the problem is friction. |
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The little "turtle" plotter exploited the fact that because the "wheels" were angled, there was actually more friction between the point of contact and the wheel. That's because as the wheel turns, there is a "scrubbing "effect. |
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Taking the ideal case, with a vertical wheel (horizontal axle), and if the axle is perfectly frictionless, friction is only required between wheel and surface if you wish to execute a turn. An "ideal" wheel moves only by rolling, it supports mass perfectly, and if the "load" has momentum it will roll indefinitely (in vacuo). |
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The shearing/scrubbing effect of an angled wheel is best demonstrated by a cornering motorcycle. Examination of motorcycle tyres that have seen some use will reveal "fear lines" at each side of the tread. When traveling straight, the machine rides on the centre of the tyre, but when cornering it tilts into the turn, countering centipetal force by the friction between the side of the tyre and the road, abrading away rubber, and leaving characteristic whorl-like wear patterns. |
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The further over the bike has been tilted, the further the fear lines will be toward the sidewall. This is why bike tyres have a more or less circular profile compared to the "box" tread-and-sidewall design of car tyres. Cars don't tilt (much) when they corner. |
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If the fear lines are right up to the sidewall, the exhaust has scrape marks, and the pillion footpegs are ground away at the ends, the rider is a right nutter and should be treated with the greatest respect. |
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Angled wheels waste energy because of the shearing forces at the point of contact. This would be MUCH less efficent that a conventional bike; on the other hand, it would demonstrate vastly improved traction, at the expense of high tyre wear rates. |
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[DC decides his typing is not so bad after all.] |
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The seabow _linky_ is exactly the idea, except with filled wheels. Thanks [BB]! |
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[8th] thanks, great info. Gotta give it some more thought... and more importantly, try it out. |
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so I would ride it doing the splits and occilating my legs like a frog? |
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Never seen a frog occilate its legs ..... |
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<sets out with torch, net and bucket for nearest pond> |
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If you watch the feet of a frog enact a planar oval that reflects the geometry of the legs and pelvis. Squatting down with legs spread you would maybe make a similar motion? my image of this bike involves the rider assuming a forward reclining posture and pumping the wheels directly (two wheels side by side. Please help me understand this idea better. |
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<Stops, puts down bucket, torch and net> |
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<Squats down with legs spread> |
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<Telephones for Paramedics> |
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sp. "angel", "cood", "affect", "uther", "gane", "weels". |
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