> Carl Fogel writes:
> >>>>>>> [...]
> >>>>>>>> no, excessively compressed rims more readily fold.
> >>>>>>> Suppose the rim is highly compressed by high spoke tension.
> >>>>>> I don't understand what you mean by this.
> >>>>> Just that the spokes are pulling the rim inward compressing it.
> >>>>> [...]
> >>>>>>> Is this right/wrong/too simplistic?
> >>>>>> I think you can test this on your own wheels (if they don't have
> >>>>>> fewer than 20 spokes) by having someone pluck spokes while you
> >>>>>> stand on one pedal and lean the bicycle with both feet in the
> >>>>>> pedals as in riding while standing.  You'll notice that the bottom
> >>>>>> spokes of the wheels lose tension unequally, the "upperside" ones
> >>>>>> losing more tension than the "underside" spokes.
> >>>>> Interesting, but my question was about something else-- how spoke
> >>>>> tension affects what happens to the rim when you hit a bump.
> >>>> As was mentioned in another thread, a rim is an elastically supported
> >>>> beam and acts like a railroad track supported by elastic cross ties.
> >>>> By performing a linear mental development of the circularwheelinto a
> >>>> linear one, some of these effects are more readily apparent.
> >>>> Consider the spokes as not becoming slack and that they have an axial
> >>>> elasticity.  The deflections (changes in tension and length) require
> >>>> forces that make rim shape mainly irrelevant.  Deflections are on the
> >>>> scale of 0.001's of inches as you can see in the diagrams of FEA
> >>>> analysis.  You can easily deform a bare rim radially with thumb
> >>>> pressure but you can't do that on a completewheelwhere spoke
> >>>> stiffness is the measure.  Please look at the deflection diagrams that
> >>>> make this clear.
> >>> Dear Jobst,
> >>> How much does a bare deep modern rim deform under thumb pressure?
> >> Oh several times as much as a standard cross section rim 36 spokedwheel,
> >> 0.050" at least.  As I said, the RIM.
> >>> I used to think that bare bicycle rims with no spokes flattened quite
> >>> easily, but posts on RBT and turn-of-the century factory claims that a
> >>> man could stand on a bare no-spoke highwheeler rim have made me wonder
> >>> about this.
> >> They lied.  Even though those were steel rims, many were U-shaped flat
> >> material.  You can sit on a bare MA-2 but it deforms enormously
> >> (about 1.5").
> >>> I don't have any bare rims, so I'm curious if anyone can put a 10 or
> >>> 20 pound weight on some aero-style hoops and report what happens.
> >> I don't have any deep-V rims either, but its not anything like a
> >> spokedwheel, whose radial rigidity is almost entirely the support
> >> element elasticity (the spokes).  Didn't you recently assess what that
> >> was?
> >>> I expect that bare no-spoke rims deform more than a tensionedwheel,
> >>> but I have to admit that I've never tried the experiment and don't
> >>> know what to expect--a tenth of an inch, an inch, two inches, a bent
> >>> rim?
> >> Well, my MA-2 did not take a set after I sat on it.
> > Dear Jobst,
> > Sigh... What a nice post, except for where you call people you don't
> > know liars about something that you've never tested.

> This is a deception of the second kind.  As I said most high wheelers
> used U-shaped rims of flat sheet metal.  That you cannot crush a
> deep-V rim with body weight is likewise true except that hollow cross
> section penny-farthing bicycle were uncommon and therefore do not
> represent the norm.  In that respect, the claim is false and as you
> pointed out, exceptions don't make the rule.

> > Here's whatRudgewrote about their 1887 highwheeler:
> > "The FELLOES are of the Clement hollow pattern, consisting of one
> > piece of steel tubing rolled and pressed into the proper shape, and
> > capable of bearing a weight of two hundred pounds, even before a
> > single spoke has been inserted."
> >  http://tallbike.com/tall/87rudge.html
> > Why not consider the possibility that you may not know everything?

> Why not consider thatRudgewas not the maker of most high wheels and
> that even these were out of the ordinary.

> > And why not consider what readers will think when you callRudgeliars
> > when I mention that their bare highwheel would support the weight of a
> > man, but then go on to state that your aluminum MA2 supported your 180
> > pound weight without taking a set, dropping a whole inch and a half
> > when you sat on it?

> Where did I maneRudgeas liars?  I find your application of
> translation to what others post unseemly and an obvious personal
> attack.  I also notice that you don't write such responses to those
> who pass disinformation to the newsgroup in rudest manner.

> > For all I know, you might even be right, but it's awfully hard to
> > credit you when you take such a bizarre approach.

> What is bizarre is your take on these things.  The information is in
> what I wrote but you choose to cite an exception in spite of my
> explanation to what rims I was referring.  I sense that you have a bit
> of jim beam disorder at work from your harsh comments to most anything
> I write.

> Jobst Brandt