Half a croissant, on a plate, with a sign in front of it saying '50c'
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BigWheel tm

Rollin, rollin, rollin, got no time for strollin, watch my tires get swollin, Raw-hide!
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//There were "farthingpennies", with the little wheel out front. As I have ranted elsewhere, bicycles are old technology that was and still is both expensive cutting-edge and simple garage-crazy. You are very unlikely to come up with something new in bicycles, and especially not new and useful.
— baconbrain, Jan 25 2011//

This ^ annotation posted to [VJW]'s 'Bicycle without chain' idea has been popping into my head at the oddest of times since I read it.
Waking me from a sound sleep, or while smashing my thumb with a hammer, or watching water spray from the wet-saw.
It's like this incessant niggling challenge, taunting me with its staunch irrefutability.
Affronting my senses like a fleck of tinfoil beneath a tooth filling.
A veritable plethora of unnovative cyclic angst.

<grabs rusty lance and saddles nag>
"Sancho! My helmet!"

The only new and useful thing I've been able to think of is to expand a bicycle's rear tire after top gear has been reached, letting riders gain far more speed pedaling downhill and maintain a higher overall speed on level stretches.

Interlocking semi-circular arcs comprise the outer rim of a tubeless wheel.
Tread coated on their outer surface, they are connected individually to the inner hub by a pantograph slider system. Centrifugal force causes the outer rim to expand at high revolutions allowing for a greater distance to be travelled per pedal stroke.


(?) Segmented tire/wheel http://cache.gawker.../2009/03/daws_5.jpg
[ldischler, Feb 06 2011]

[link]






       Do you mean centripetal force?   

       The problem here is that the expanded wheel will mean the frame stays will have to be fixed a certain distance from the hub, and also the saddle, luggage rack, mudguards etc. i.e. you gain nothing by shrinking the wheel in the first place and may as well just add more gears.   

       On the other hand if this could operate on only a segment of the wheel, so that the segments expand as they go down to the ground, and contract as they come up again, it would be more practical. To keep saddle and rider height constant, the hub could be mounted on a slider or arm so that the hub rose as the bottom half of the wheel expanded.
pocmloc, Feb 05 2011
  

       //centripetal// No, he means centrifugal force.
spidermother, Feb 05 2011
  

       I have created a monster.
baconbrain, Feb 06 2011
  

       That's a pretty cool image [pocmloc]. I see it like a variation of the portable jump idea but continuous.
You are probably right [21Quest].
I don't know what I mean anymore [spidermother], the force that holds the water in the bucket when I swing it in a circle.
Perhaps [baconbrain], perhaps. It's not keeping me up at night anymore so that's a good sign ... right?
  

       I've seen a design like this for a car, but that was twenty years ago and I can't find a picture of it now. Some crazy UK designer. There are also segmented tires that expand to the side rather than outward.
ldischler, Feb 06 2011
  

       The concept of 'smart wheels' was used in Neil Stephenson's 'Snowcrash' (wasn't everything?). But not quite as described here. In Stephenson's book, the wheel segments were on individual spokes that slid in and out of the central hub as the segments hit irregularities in the road surface; thus keeping the vehicle's ride as flat and smooth as possible.
DrBob, Feb 07 2011
  

       I'm thinking that the weight of the rim would have to be excessively high to create enough centrifugal force (it exists in a rotating reference frame) to keep from collapsing under the riders weight at at any reasonable speed.
MechE, Feb 07 2011
  

       //BigWheel tm// sp. BigWheel™
spidermother, Feb 07 2011
  

       //The concept of 'smart wheels' was used in Neil Stephenson's 'Snowcrash' (wasn't everything?)//   

       It might well, have included Enki and the Nam-shubs, but it made no mention at all of shuriken pizza, so much for futurology.
not_morrison_rm, Feb 08 2011
  

       It did have pizzas though, and Gibson's 'neuromancer' had shuriken. So close.
spidermother, Feb 08 2011
  
      
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