Oddball wheel question

[Leo Lichtman]

"George Herbert Walker" wrote: I said the component in question- the
spokes- make no contact with any external system.
^^^^^^^^^^^^^
You are certainly correct on that point. My quibble is that the spokes ARE
involved in transitting the load to the ground. Each spoke undergoes a
cyclical variation in tension as the wheel rotates--this variation produces
a resultant which pushes the axle upward. So, I do not see how it is
relevant that the spoke does not connect directly to the rider's butt, or to
the ground.

 

[Blair P. Houghton]

<[email protected]> wrote:
>This may be an old chestnut, but I'm curious what people
>have to say.
>
>Briefly, Kraig Willett took a 3-spoke rear wheel, cut a

Bad news: Those aren't spokes. They're struts.

You can't use 3 spokes on a wheel, because you can't
maintain constant tension in that configuration (you could,
if you had strong enough spokes).

I have no doubt that, especially with one of the struts
cut, the force in each changes from tension to compression as the
wheel spins.

And this statement is just false:

"A little known semantic debate revolving around the details
of how bicycle wheels structurally support loads has been
raging on the usenet newsgroups for quite some time."

IIRC, this was cleared up long before there was a Usenet,
and then we cleared it up shortly after it started coming
up on Usenet. So the only thing "raging" is people
thinking there's any question that actual bike spokes are
always under tension. Oh, and it's a physical debate,
not a semantic one.

--Blair
"And yes, he voided the warranty."

 

[Blair P. Houghton]

Werehatrack <[email protected]> wrote:
>Rather than going through this Yet Again, might I suggest a bit of
>Googling and a trip to whatever library has a copy of Jobst's book?
>For a normal spoked bike wheel, if you look at it from a vector force
>change standpoint, the answer is that the largest vector change is in
>the spoke which most nearly points down, and by a perfectly valid but
>counterintuitive engineering principle, this means that the wheel
>"stands" on the spoke(s) at the bottom.

Okay. *That* would start a "semantic" argument around what
you are doing to change the meaning of the word "stand".
But it would end when you realize you can't "stand" on
something that your foot is pulling upward.

Just because the "vector force change" is "largest" in
the bottom spoke doesn't mean it results in a change from
tension to compression in that spoke, or any other.

The truth is, your hub hangs from the upper half of
your wheel and pulls up on the lower half of your wheel.
It also pulls forward on the rear half of the wheel and
backward on the front half. In fact, if you split your
wheel in half at any angle, the hub and spokes are pulling
each half of the rim towards the other. All the time,
from the time it's built until it's dismantled or broken.

--Blair
"Isn't this in the FAQ? And isn't it
answered correctly?"