re: Wires v alloys again

[Alex Rodriguez <sicar@xxxxxxxxxxxxxxxxxxxxxx>]

> >Date: Tue, 27 May 2003 18:37:45 -0600
> >From: C M Smith <cmsmith@domain.elided>
> >Subject: Wires v alloys again
> >
> >Provocative maybe, but what I see posted about this topic substantially
> >supports my original post. Wire wheels are an anachronism, no longer
> >suitable for use on automobiles. Interesting stuff about how bicycle wheels
> >work and reverse tension (compression???) and so on. Fact is the spokes
> >work in tension and the net effect is the bicycle hangs from the top spoke
> >on each wheel. Sure, ALL the spokes are in tension but so what?
>
> Wrong!  A bicycle does not hang from the top spokes.  The load of a bicycle is
> supported by the bottom spokes.  What makes it hard to understand is that a
> bicycle wheel is a prestressed struction and will only work as long as 
> there is
> tenstion in the spokes.  Without tension, a spoked wheel will collapse.  You
> can do a very simple experitment to prove this.  All you need is a bicycle
> and a volunteer to help you.  With no load on the bike, pluck a couple of the
> spokes on the rear wheel that are at the bottom of the wheel.  Then have your
> buddy sit on the seat.  Pluck the spokes at the bottom again.  You will notice
> that the tone of the spoke will get lower.  That tells you that the tension in
> the spoke went down.  Have your buddy get off the bike again.  then pluck the
> spokes at the top of the wheel.  Then have your buddy get on the bike.  Pluck
> the spokes at the top.  You will notice the tone of the spoke did not change.
> That tells you that when loaded, the tension in the top spokes did not change.
> If your theory were correct, that the bike hangs from the top spokes, then the
> tone on the top spokes would change, but it doesn't.  As someone else
> suggested, you should get a copy of "The Bicycle Wheel" by Jobst Brandt and
> read about how a bicycle wheel works.  It is pretty straight forward once you
> understand what is happening in a wheel.
>
>
> >Wire wheels are  heavy, hard to maintain, expensive, and not as rigid as
> >alloy wheels pound for pound. End of debate.
>
> For a car wheel, this is true.  For a bicycle, it is not.
>
>
> >and let the controversy continue.
> >Michael Smith
> >White 1991 164L
> >Original owner
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Alex     __O
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