Old 07-30-15, 11:46 AM
  #37  
McBTC
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Originally Posted by FBinNY View Post
The phrase "stands on the bottom spokes" is part of the problem. It's a semantic trick whereby someone describes a reduction of tension as a compression. In that way it's analogous to how some in Congress will describe a reduction in revenue, ie. a tax credit for certain items, as an "expense". Yes, it's functionally the same in terms of the net effect, but it's not the same thing.

Moreover, the concept of "standing on the bottom" belies the actual condition, which spreads the changes among ALL the spokes. In the case of a more flexible rim, the tension of spokes near the bottom increases along with all the others.

We can debate semantics forever, but the only realistic models are those that describe the entire system, and discuss net changes in tension bottom to top, including the sides.

If you consider that a deflected rim would ovalize under load, you can see that the hub is also supported from the sides at the same time.

BTW- one of the problems in all wheel discussions is that many people (on all sides) are simply repeating things they've heard and read, and have become very committed to in a way that someone stranded in the ocean clings to whatever floats.

So to those who want to understand this kind of stuff. Don't latch onto partial explanations. Stop, think, draw yourself diagrams and sketches, and try to see the whole picture, not a few pixels.
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Forget about "standing" and "hanging" if that only invokes thoughts of nothing more than a debate over semantics. The real question is which spokes are actually doing the work and that has been calculated by engineers using finite element analysis. The spokes at the bottom are carrying the load so that evokes the use of a word like 'stands' to connote something being supported by something else that is resting on the ground, as opposed to the word 'hangs' that might seem more appropriate if the physics of the matter were more like a hub being supported from something else above the hub. Jobst Brandt ("The Bicycle Wheel") is pointed to as the seminal work on the structural mechanics underlying the functioning of the bicycle wheel.
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