hanging bicycle by wheel

For storing my bike when I'm not using it, I'm thinking about hanging it
up by its front wheel. Basically, I have this big hook that's attached
to the ceiling and I'll just hook in the rim of the front wheel.

Is this a bad idea? Will it hurt the rim (un-true it) or eventually
mess up the head and/or the fork?

What about hanging it by rear wheel? (this is harder to do for me) Or
maybe hanging it by both wheels? (maybe the utility closet is big enough)

Please try to reply directly to me. I'll post a summary when the
responses die out.

-Dave
pas...@andrew.cmu.edu

Don't do it. Your rims will stretch as well as your spokes. It will also
cause the grease to drain of the races in your head set and cause your
frame to age from reversing the stress of gravity that the bike was
designrd for.
Joe King

So, Jobst answers, with his usual firm conviction:

>The only parts you should avoid using when hanging a bicycle are the
>soft parts like saddle, tires, cables and the like. The rest can hold
>the weight effortlessly for years, on a single hook.

Joe's almost simultaneous, and equally adamant response:

>designed for.

I have only one response to this entire thread: huh??

Anybody want to break the tie? ;)

> First, Dave queries:

I will...go to a bike shop and see how they store their bikes...especially
in the mechanics area. I have seen many bikes hanging by their front
wheels, but this does not mean that it is good for them either (gee I'll
bet this sounds like I'm fence sitting). I have found that many small bike
shops (small=not much space) hang bikes so that they can display more of
them. So I would conclude that hanging a bike wouldn't do it any harm in
the short term...long term storage may be another problem. Check it out
with a bike mechanic if you want long term storage...perhaps you might
need to rotate the wheel occaisionally to alleviate stress on the spokes.

Cheers,
Sid.

Sarcasm doesn't work well on the net, huh.

--
=============================================================================
Don Finan
dfi...@ucs.indiana.edu ...but these go to eleven.
=============================================================================

Joe should take some materials courses. A bicycle is designed to take
the stresses of up to a 100kg+ person pounding on it for significant periods
of time. I find it difficult to believe that the stresses of its own weight
(10-15 kg) are going to cause any damage. The materials used in the
construction of the bike are genrally equally effective in tension and
compression, particularly since buckling is not likely to be a factor at the
greatly reduced loads involved.
For permanent deformation to occur, loading must be sufficient to
exceed the yield strength of the material. Below the yield stress,
only elastic deformations occur, and these are (by definition) reversed when
the load is removed.
As to grease draining from the races, Joe should try using something
thicker than vegetable oil in his headset. Using grease, I've never had a
problem with this. If you look at a typical headset, the grease is always free
to flow away from the bearings and into the head tube, should it be inclined
to. It doesn't...

:
: >I have only one response to this entire thread: huh??

:
: I will...go to a bike shop and see how they store their bikes...especially

--
Craig West Ph: (905) 821-8300 | It's not a bug,
Pulse Microsystems Fx: (905) 821-7331 |It's a feature...
2660 Meadowvale Blvd, Unit #10 |
Mississauga, Ontario, CANADA L5N 6M6 | cr...@pulsemicro.com

< SNIP >

In that case, you will want to rotate the wheels occasionally if you store
it standing up. The bike will be exerting the SAME *MASSIVE* forces on
the rims and spokes regardless. How about we fill the tires and frame with
helium and float-store the bike?

<>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <><
Jonathan...@JCI.Com, Johnson Controls Inc, Goshen, Indiana, USA
Associate Engineer -- UNIX Administrator -- CAD/DTP Graphic Designer
RC Helicopter Pilot -- Takeoffs are optional, Landings are mandatory
* Member of the Northside Church of the Nazarene, Elkhart, Indiana *
<>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <><

On another gravity related note, have you ever noticed slight bulges on both
tires as you begin a ride? My mechanic, Mr. Boltzman of Reversible Cycles,
says that this is due to the "pile up" of air in the lower portions of the
tires. He recommends lifting the bike and spinning both wheels for a minute or
so to aid in redistributing the air.

Any frequent reader of wreck.bikes should know Jane and her various aliases by
now. How dreary a place this was without her!

__________________________________________________________________________
Dept Atmos Sci, Univ of Washington sal...@atmos.washington.edu
http://atmos.washington.edu/~salathe

: Jobst Brandt <jbr...@hpl.hp.com>
Of course Jobst is as right as Newt on this one, but hanging your bike
invertrd from the ceiling(hay,,thats how you pronounce my last name)
could and should be examined a little first. First,,,are you sure that
your quick releases are tight enough?,,,Water could migrate up the old
seat tube and get in between the tube and post via a little capillary
action and cause you to do the old stuck seat post post,,the post we all
love the most,,,,next one I see is toast with "Joe King" putting the
butter on really thick. FIRE....Picture one of those slowly brewing fires
in a closed room,,,,,,heat building on the ceiling,,,,just waiting for a
little air and a good catalyst......I really don't know if a bike hanging
from the ceiling would present any big time fire hazard....just a
thought.....
Jane<not Joe King this time>Selin

In article <DEwAp...@news.arco.com>, Eric Siegmund <esi...@is.arco.com>
wrote:

Bwaaaaaaaaaaaahaaaaaaaaaaaaaahaaaaaaaaaahaaaaaaaaaaaaaaahaaaaahahahahahaha

Jim

Are you daft?! Hanging a bike has no effect on the aging of the frame.
The bike was designed to be ridden and withstand the stress of the rider
and the forces being applied to ride it, not to resist the force of
gravity! Bikes are hung from their wheels by dealers for a year or more
with NO effect on the roundness of the wheel. You shouldn't have enough
grease in your headset to cause it to run in the first place, and in any
case I doubt the room the bike was hanging in would be hot enough to
liquify the grease enough to run. That's why grease is used in the first
place, so it wouldn't leave the bearings.
The only bad thing that could happen from hanging your bike by
the front wheel is that if you're too rough with it (heavy bike and
flinging it into the air to catch the hook) is that you couild end up
with a pitted headset after a while. If you're careful, or hang it from
the rear wheel, there is no problem.

kyle

I don't know about the rest of you, but if I thought that my wheel
couldn't support ~30 lbs of bike I wouldn't want to put my 180lbs
on it and thrash down any trails!!!!!!!
BS

-Hal King

This is a fine idea, but to avoid several dire problems, pointed out in this thread,
it probably would be a good idea to hang the bike by the rear wheel in alternate months.

That is only if you think the amount of elastic stretching
of the wheel can eventually become permanent - which
is unlikely. In any case, the stretch of the rim is somewhere
in the neighborhood of 100 nanometers for a hook
supporting an entire bicycle. If your wheels are within an order
of magnitude of that roundness you are a better wheel builder
than anyone I've ever met.

--
---------------------------
Dave Blake
dbl...@bme.jhu.edu
" The more you drive, the less intelligent you are." - Repo man

Best way to rotate the wheels is to get on the bike and pedal.

: On another gravity related note, have you ever noticed slight bulges on both

Well, that works, but I noticed that after rotating the tire
for several minutes, the bulges go away. (If they remain, you're
not rotating them fast enough.) Anyway, if you change the air
often enough, it tends not to pool up in the lowest point.

--
Hank Barta White Oak Software Inc.
hba...@interaccess.com Predictable Systems by Design.
Beautiful Sunny Winfield, Illinois

Stretching rims???... Draining grease???... Stresses of gravity???...

1) Rims don't stretch (well, let's say that when they do, you have bigger,
probably dangerous problems at hand).

2) Grease doesn't drain (unless you're using bacon grease from breakfast)

3) Bike frames aren't designed around the stresses that gravity puts on
them, but around the stresses that riders put on them.

What a fragile bike Joe must own. I suggest putting it under glass so a
breeze doesn't turn it into a pile of twisted junk.

Greg

Well, that's probably because you're using a pump that produces heavy air.
You need to use an adaptor that converts it to light air--has fewer
ions--and the air tends then to distribute itself more evenly around in
the tire over longer periods of time. this has worked for me for years.
--
_______________________________________________________________________
Rod Hutton || Disclaimer, Datclaimer!
Columbus, Ohio || What's all dis about a
<rhu...@freenet.columbus.oh.us> || Claimer?

Rod,

I really like that lighter air adapter that you mentioned for the pump. Are
those generally available? I have just gone through all my catalogs and
didn't see any.

I guess that I could have asked some of my friends who went to get me one at
Interbike. I am sure that they would have been available there!

I have been watching this thread for a while and I am still puzzled over one
thing. Someone said that if you hung the bike upside down that the grease
would run out of the headset.

What I am wondering about is why, when the bike is standing upright, the
grease doesn't run out of the headset that way. I guess that all grease
that is used in headsets is unidirectional and will only run out if it
knows that the bike is upside down.

I sure would like to get one of those air adapters. Please tell me where
I might find one. Thanks. And, oh by the way, do they come in titanium?

Jerry

etc.
etc.
etc.

> kyle

OK Jane, you have caught your limit on this thread. Anyone who bites
after Kyle here must, I repeat MUST, be thrown back in.

Jeff Carlson

Different stresses. When you're on the bike all the force is directed
to the hub and supported by the spokes. If you hang a bike by a wheel
the force is directed away from the hub, again supported by the spokes
but they're designed for force in the other direction.

You'll all excuse me a bit while I go spin my wheels so the heavy air
doesn't pool at the bottom.

jim

--
"I want to die peacefully in my sleep like my grandfather. Not screaming
in terror like his passengers."

Jim Harkins jhar...@netcom.com
San Diego, CA.

> My reason for
>this is simple, I would rather bump my head on a wheel than loose hair and
>flesh on the handle bars and the stuff on the handle bars. <Do not mention
>always wearing your helmet here.>

Richard clearly doesn't want to merge this thread with the Great Helmet Wars thread,
but he has also described how to prevent damage from the common at-home accident
of bumping into a suspended bicycle. This is a good safety point, Richard, and you
are to be praised for bringing it up.
Of course, for you libertarians who don't want to make helmet-wearing a rule at home,
your home-owner's or renter's insurance should cover injuries.

Ian

>
>So, when your bike is just sitting around on the ground, roughly half of
>the forces that act on the wheel while hanging are acting on the wheel
>just because of gravity. Better to store your bike in geosynchronous
>orbit so that the wheels don't deform...
>
This is not practical for most of us who don't work for NASA. Do you have
any idea how much it costs to launch a bicycle into geosynchronous orbit?
Hundreds of dollars, _each way_

It is also irresponsible to suggest this, because the geosynchronous orbit
is getting overcrowded already. If I put my bikes up there, there wouldn't
be room for anybody else!

In addition, the unshielded uv radiation from the Sun would age your tires
prematurely

I think cousin Paul ought to get a grip on reality.

I have found a perfectly satisfactory solution to this problem, I keep my
bikes floating in a large pool of mercury. This supports them naturally
not concentrating the stresses on any one part. Mercury, in its metallic
state is not as toxic as some people would have you think, but I do remove
my water bottles before I store the bike--you can't be too careful!

Sheldon "Quicksilver" Brown
Newtonville, Massachusetts

1957 O.T.B. (63 speed)
1970 Raleigh/Raleigh homebuilt tandem (mtb)
1954 Columbia (springer ballooner)
1974 Brown (criterium/hybrid)
1974 Moulton MKIII (work in progress)
1972 Peugeot PX-10 (now a PX-4: 4-speed Sturmey-Archer FM)
1972 Raleigh International (fixed gear)
1974 Raleigh/Raleigh homebuilt tandem (road)
1930's Hercules (fixed/2 speed freewheel mtb)
1970's Raleigh 20 non-folding (5-speed hotrod)
1985 Fat Chance (mtb)
1958 Raleigh Lenton Grand Prix (3-speed Sturmey-Archer ASC fixed gear)
1960's Raleigh Chopper (Ugh...horrible)
1982 Rudge/Dunelt homebuilt tandem (54 speed road-former kidback)
1950's Raleigh Sports (27x1 wheels, chaincase, lightened 3-speed)
1970's Raleigh 20 folding (fixed gear)
1930's Elgin (balooner)
1983 Repco (Nishiki Cresta-tourer built for the Australian market)
1954 Rudge (fixed gear w/milk crate for shopping)
1992 Cannondale SR 800 (Black Lightning)
1993 Cannondale ST 500 (fixed gear rain bike)
1930's Torpedo (German-cobblestone bike)
1961 Schwinn Paramount (Campagnolo Ergo, Shimano derailer)
1970's Piccio tandem (fixed gear)
1970's Raleigh 20 folding (3-speed hotrod)

This is silly. Metal does not undergo creep deformation except at very
high temperatures and pressures. My bikes hang by their front wheels for
five months of the year (Michigan winters...@#%&*) and I'm somewhat
fanatical about true rims. I check them. They DO NOT show any effect at
the hanging point. Zero. Nothing. Don't happen.

: >>cause the grease to drain of the races in your head set and cause your

: Sounds kinda ridiculous to me. I've never had any grease drain out of any bike
: part. Oil might drain, but grease? Try this: take a gob of grease and stick
: it to the wall. Check back in a year, it'll still be there.

Right as far as I can see. My grease goes nowhere over the winter. And
the blob of grease my grease gun spatted on th 2x4 wall stud near my
repair stand has been there for three years. All it's done is get
dusty. It doesn't run.

--
Lee Green MD MPH
Dept Family Practice
University of Michigan
gre...@umich.edu

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Hmmm, you have not read Jobst book. In normal riding the hub is supported by
the bottom spokes with compression. Spokes compress? Yes - because all
spokes in the wheel are in very high tension so they can compress a bit and
still stay in tension. If the rim hung from the upper spokes the lower spokes
would slack, the nipples could turn, and then they would loosen up more. This
is how improperly tensioned wheels loosen-up on the way to self destruction.

I do not agree with Jobst on hanging the bike by the seat is bad. But, you
must place the hook on the metal part of the seat only. Since the metal can
support a 170 lb rider why not let it support a 20 lbs bike. The trick is to
not let the hook deform the softer parts of the seat. This may not work with
all seats or you may need to make a special hook that will work. You may not
want to do this if your seat rails are made of unobtainium. My reason for

There is nothing wrong with handing a bike by its wheels though. The forces
are minor compared to actual riding.

Richard Kaiser
Pasadena, CA
rka...@primenet.com
(was rka...@netcom.com)

or if you prefer, i have a product that is for sale (built after reading
these posts) that hangs the bike by the quick release and the 2 motors
slowly spin the wheels at 1 rpm. this ensures that everything stays
round :-)

--
Rick Schultz
mis...@beach.net

When you go to a shop and look at the mechanic's bikes, you can rest assured that
those bikes are ridden - probably ridden often. The action of riding the wheel
(especially if that wheel is properly tensioned, as those of mechanics usually are)
will tend to force the wheel back into roundness again. I agree that if you intend
to leave the bike for months it would be a good idea to store it in a different way
or at least to rotate the wheel every once in a while. But 20 lbs of bike is no
strain at all compared to 200 lbs of bike+rider.

Paul
USF Bike Shop
kc4...@cftnet.com

(I just had to say it!)

Tapsa

JBR

: I have found a perfectly satisfactory solution to this problem, I keep my

I would consider this solution if I could be sure that the mercury
wouldn't have an adverse effect on my 24k gold plated White Industries
front and rear hubs. Currently, I pop my bike into a pyramid that I had
built in my back yard after it's been hanging by the wheels for a while.
The Pyramid fixes the frame and wheels, but I still have to repack the
headset. I know,,,,,I could just hang the bike in the pyramid, but, I
only have enough room to support my razor blade re-sharpening biz.
I'll have to get more info on the mercury before I try it.
Hugh Merlis

: : >>Don't do it. Your rims will stretch as well as your spokes. It will also

Wow, Jane "aka Joe King" Ajax Titanium Selin even scored Lee's
scalp^W^H^H^H as a victim.

But he must be mistaken, because everyone knows that Bike Fridays are
designed not to be greased at all, otherwise they spontaneously
disassemble.

Mark "Will hang upside down for food" Madsen

--
________________________________________________________________________
Mark Madsen: <m...@ansa.co.uk> <URL:http://www.ansa.co.uk/Staff/msm.html>
Information Services Framework, The ANSA Project, APM Ltd., Castle Park,
Cambridge CB3 0RD, U.K. <URL:http://www.ansa.co.uk/>; <a...@ansa.co.uk>
Voice: +44-1223-568934; Reception: +44-1223-515010; Fax: +44-1223-359779

> It's blatant misinformatation like this which demonstrates the current decline
> in Usenet standards. The pressure difference would only be an additional
> 100 kPa, or 14 psi. Your tyres should have at least that large a safety
> margin. Of course, the UV would still be a problem...
>
> (for the terminally humour impaired, :-) )

You can elimate the UV problem by keeping the bike in orbit around Mercury
(on the dark side).

Furthermore, I strongly object to your use of the term "humour impaired".
Impairment implies a deficiency of some sort; something that is lacking.
It has a very negative connotation. You should use "humour challenged",
which has positive connotations.

Mike

I'm not sure you could launch a bike into orbit, seems to me strapping
those solid fuel boosters to the bike and lighting them off would rip the
poor bike apart. May I recommend renting space on the shuttle or something?

As for cost, first thing you do is get a government grant. May I suggest a
title along the lines of "Tendencies of circular strips of metallic alloys
bordered by artificial rubber containing 80 atmospheres of pressure to become
ellipsoid in gravitational fields upon application of force at a single point,
compared to similar objects outside of major gravitational fields". That will
be $200,000 please.

No real need for a geosynchronous orbit, you just need to be able to predict
a) when will you want to ride next, and b) when will the bike pass over
your house immediately prior to that time.

Not to mention the pressure in the tubes would blow them off the rims.

If the spokes compressed, they would buckle; the weight is supported by
the hub HANGING from the rim.

It's blatant misinformatation like this which demonstrates the current decline

:
: jim

:

--
Craig West Ph: (905) 821-8300 | It's not a bug,
Pulse Microsystems Fx: (905) 821-7331 |It's a feature...
2660 Meadowvale Blvd, Unit #10 |
Mississauga, Ontario, CANADA L5N 6M6 | cr...@pulsemicro.com

Actually, if you can convince them that you are affiliated with an
educational institution its only 10000 dollars; otherwise, its 25,000
dollars;-)

: Rod,

<snip>

: I sure would like to get one of those air adapters. Please tell me where

Jerry, I would think it would be obvious that titanium light air adapters
are superfluous, when simply using the adapter according to the
instructions automatically decreases gross weight, up to the
limits of tire pressure, of course. Save your money, the cast
adapter is just as good.

--

*--------------------------*-------------------------------------*
| | |
| Mark Schecter | "Please identify yourself." |
| sche...@tfs.com | (Self checks pocket mirror) |
| | "Yes, that's me." |
*------------------------- *-------------------------------------*

Once I was pumping up my tire and the air wouldn't go to the other side
of the tire. Half of it was firm and the other half flat. I decided to
walk the bike and after a a few hundred yards the air finally went to the
other side of the tire. Pheww!

Jeff

Baw T. Lection

Oh, that's because you were using "dizzy air". It got tired of going around
and around and around, so it locked itself into place to keep itself from
getting dizzier still. If you've seen a bicycle on, say a rack on a moving
vehicle, and the tire is just sitting there spinning itself without any
apparent locomotion, that's a case of DA.

I bought a bunch of used bikes with DA and hooked up generators to each. I
run my laptop off of this perpetual motion...

The other Jeff
--
---- Jeff McDonald --- mcdo...@hartwick.edu --- words belong to sender ----

Only one day and already I've learned so much! ;)

-- Louise Penberthy

--
Louise Penberthy | Unofficial Channels:
LCC, Georgia Tech | About Walter Skinner and Mitch Pileggi
lou...@cc.gatech.edu | link from the URL below
http://www.gatech.edu/lcc/idt/Students/Penberthy.html

If you try and build a wheel thinking "the bike hangs by the upper spokes" you
will not get the tension high enough and the wheel will fail. The failure mode
is not buckling spokes as you suggested, but is spokes that slack on the
bottom. This may allows the nipple to turn and loosen even more. It also
subjects the spoke to sudden stresses when tension returns to the spoke and
eventually causes fatigue failure of the spokes.

WHAT? finite element analyzis(sic)? What does the studying the
composition of the spokes have to do with this discussion?

Read your own sentence.
Tension is the result of force acting to pull that spoke (longer); how
can a decrease in tension(a shortening) of that spoke be supportive?

The spokes are analogous to rubberbands: Reducing their stress does not
equate to them supporting a load. If they were supporting the load, the
change in tension would be positive, not negative ("a decrease
in...tension.") as YOU assert. As the spokes that actually support the
wheel are stretching, the tension on the lower spokes is relieved. If
they were not pre-stressed (tightened) they would buckle. since they are
already stressed, they simply move closer to their unstressed state. It
is here that you are close: If they are not tight enough, the release of
tension would be too much, THEN they would loosen or (Obviously, they
would go slack before they buckled) buckle.

An easy to understand model can be constructed by suspending (damn,
there's that word again) a small object between two rubberbands. Tack
one of the bands to the floor and the other to a table. The bands will
simulate spokes. If you have them tight enough, you can grab the object
and push it down (simulating weight on the wheel) with out the lower band
losing tension. However, at no time does that lower band actually
support the weight.

I'm not sure about the rotation direction, someone want to clarify this?

--
<>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <><
Jonathan...@JCI.Com, Johnson Controls Inc, Goshen, Indiana, USA
Associate Engineer -- UNIX Administrator -- CAD/DTP Graphic Designer
RC Helicopter Pilot -- Takeoffs are optional, Landings are mandatory
* Member of the Northside Church of the Nazarene, Elkhart, Indiana *
<>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <>< <><

The assertation that the hub hangs from the top spokes is false. What is
happening here is that the spokes are prestressed in tension. Since we are
working in the linear elastic region, the effects of different loadings
can be superimposed.

Loading 1: Tension in the spokes.

Loading 2: Concentrated load at the bottom of the rim.

This concentrated load bends the rim toward the hub (slightly), in
reducing the tension of the spokes between the hub and the bottom of the
rim.

If you want to test this, Have someone sit on a bike that has well
tensioned wheels, and pluck the spokes on the top and the bottom. You
should find that the top spokes have a higher pitch than the lower ones
when under load, but the same pitch as the ones to the front and back.

eric

--
sor...@u.washington.edu

> rka...@primenet.com (Richard Kaiser) wrote:

[in an earlier post]

[Richard Kaiser replied]

Read the book (The Bicycle Wheel, by Jobst Brandt) and you will find out
what finite element analysis is, as well as understanding how it is that a
wheel stands on its lower spokes rather than hanging on on the upper ones.

Read the book.

> The spokes are analogous to rubberbands...

Read the book.

> there's that word again) a small object between two rubberbands...

Read the book.

--
David Casseres
Exclaimer: Hey!

[deletia about launching a bicycle in orbit]

You are joking right? Inflated bicycle tires in outer space would only
increase pressure 1 atmosphere or 15 PSI. All tires have a much larger
safety margin than this.

--
Bruce Jackson | P. O. Box 13886-NT | GAB 550E
UNIX Systems Admin. | Denton TX 76203-3886 | (817)565-2279
Computer Sciences | jac...@cs.unt.edu | FAX (817)565-2799
Univ. of North Texas | http://replicant.csci.unt.edu/~jackson/

In article <446bhc$n...@clarknet.clark.net> ake...@clark.net (Pete Akerson) writes:

>> M Dolenga (mp...@cornell.edu) wrote: : : You can elimate the UV

: Mercury doesn't spin, so that'd be a parallel
: orbit 'round the sun.

Pardon me, but what does Mercury's spin have to do with anything? Only
the relative position of the planet and the sun matters. There is an
orbit on the far side of Mercury which will keep the Sun blocked, but
I am fairly certain that that Lagrange point is unstable. Perhaps it
would be easier to put a UV protecting cover around the bike. Now,
about them micro-meteorites : -)
--
----------------------------------------------------------------------------
Tom Clune
email:cl...@solarz.colorado.edu
Work: JILA, Campus Box 440 Home: 1406 Cypress Circle.
University of Colorado Lafayette, CO 80026
Boulder, CO 80309 (303) 604-6479 (machine)
(303) 492-7851 (Office A-504)
(303) 492-8769 (Lab)
(303) 492-5235 (Fax)
----------------------------------------------------------------------------

Yes.

>Why is the tension on them lower? Because the upper spokes are
>experiencing INCREASED stress which tensions them more, hence, they have
>a higher pitch. All of the spokes that are higher then the hub will
>experience more stress; with the amount of that increase increasing the
>closer you get to 12 oclock high.

Nope.

The spokes between the floor/road and hub experience tension changes
far far greater in magnitude than any other spokes. Including the top
spokes.

On a properly built wheel, the spokes are tensioned just below their
elastic limit. If the hub hung from the top spokes then those spokes
would stretch and the the wheel would quickly, and irreversibly,
become untrue. This isn't what happens. Instead, spokes on the
bottom loose tension allowing the nipples to turn, lower the spoke
tension further.

Have you checked the pitch of your spokes both with you the bike, and
with you not on the bike?

-Jason
--
-------------------------------------------------------------------------------
J. Harr...@cs.ubc.ca http://www.cs.ubc.ca/spider/harrison
Graduate Motto: Free-time with guilt. ftp://ftp.cs.ubc.ca/pub/local/quotes
--
-------------------------------------------------------------------------------
J. Harr...@cs.ubc.ca http://www.cs.ubc.ca/spider/harrison
Graduate Motto: Free-time with guilt. ftp://ftp.cs.ubc.ca/pub/local/quotes

Think (logically) for yourself!

unscrew. Why is the tension on them lower? Because the upper spokes are

Hey, youse guys are out of date! It used to be thought that Mercury was
tide locked into a fixed position with respect to the Sun, much as the
Moon is with respect to the Earth.

According to this theory, one side of Mercury was constantly in daylight,
the other in perpetual darkness. The band around the edge was called the
"Twilight Zone", a name adopted by Rod Serling for a popular TV show.

More recent observations with more sophisticated equipment, including the
Mariner 10 probe in the early '70's, have revealed that while Mercury orbits
the Sun every 88 days, it revolves on its axis every 59 days.

The planet is inhabited by a wise and ancient race that spends all its time
at the beach, because the weather is always nice and warm.

Sheldon "Is There Mercury On Mercury?" Brown
Newtonville, Massachusetts

+------------------------------------------------------------+
| To stay young requires unceasing cultivation |
| of the ability to unlearn old falsehoods. |
| --Robert A. Heinlein |
+------------------------------------------------------------+

Read the book. You don't have the faintest idea what you're talking about.

: In article <446ajv$3...@ns2.ny.ubs.com>, NNYWTJ <NNY...@ubs.com> wrote:
: >
: > Think (logically) for yourself!

Well and wonderful. But one really ought to consider the arguments
of experts before relying on one's initial thoughts.

: > The pitch on the lower spokes is lower because the hub has moved closer

So lets go... The hub has moved closer to the bottom of the rim,
or the bottom of the rim has moved closer to the hub. The key
consideration is how the rim deforms. Start with the absurd
situation of two spokes, one at 12 o'clock and the other at 6.
Your picture of the wheel is that the rim stays fixed as the
hub moves down. The basic problem is this: if the applied force
were evenly distributed between the top spoke and the bottom
spoke (tensioning one, detensioning the other), then the rim
could *not* deform. Now forget the wheel and just look at
the rim. If the bottom is pushed up, how far would the wheel
have to deform in order for supports at the top to feel a
significant amount of force? Quite a bit. How far would it
deform if the supports were near the bottom? Not very much.
This description is only a cartoon model, but I hope the
point is clear.

For a real wheel the bottom of the rim deforms slightly, so the
top should only have a small increase in force (tensioning the
top spokes) while the bottom has a relatively big increase in
force (detensioning the bottom spokes). So without looking
at Jobst's book, I expect that the top spokes will experience
a slight increase in force, but the bottom spokes will bear
most of the load. Which of our "thoughts" is closer to
the truth? Let's go look at the experimental evidence.

David Casseres (cass...@apple.com) reiterates:
: Read the book. You don't have the faintest idea what
: you're talking about.

Ditto.

David Olson
dao...@math.mtu.edu

How do you equate the wheel's deformation (yielding) with support?
The actual bottom spokes (where the wheel is flattened) does not support,
all the other spokes that are not on the bottom do. The only way a spoke
gives any resistance is when you try and stretch it (it can't resist a
crushing force until after it is completely slack. They are under
tension so that when the rim does deform, they remain under tension and
keep the rim true( a lateral force to the downward weight of the bike
plus rider). As the wheel deforms, part of it gets closer to the hub
(the part that yeilds) and part of it trys to get further away (until it
buckles). The spokes hold this together (in theory), that's why spokes
get _pulled_out_of_rims-- not pushed in.

So... It doesn't actually "hang" from the uppermost spokes; but, it's not
supported by the bottom-most spoke either. The spokes that are slackest
(at the point of defamation) are _not_ supporting it; those spokes around
it are. Spokes support by tension as the wheel deforms and goes out of
round, the area on either side of the flat part wants to get further from
the hub; those spokes stop that from happening -- this is evidenced by
their increased tension. I've been out of school way too long to try to
explain it mathmatically; I have to rely on semantics -sorry:-{). I
stand corrected on my assertion that the hub "hangs", but it clearly is
not _supported_ by slack spokes.

See, the learning process illustrated. As we discuss (argue?) this my
college physics classes are coming back to me and everything. If I had
paid more attention during the vector analysis stuff, I could've
articulated this much more coherently... Oh well

Remember, don't let idiots near your bike if you're hanging them by the
wheels and you have quick release hubs, especially idiots like me.

NNYWTJ (NNY...@ubs.com) wrote:

I gather you still haven't looked at the experimental evidence?
Please do that before you do any further posting on this subject.
Then if you don't understand, start a new thread, or ask Jobst
via email. Just recognize that your half-remembered college
physics doesn't put your thinking in the same league as practicing
engineers. Don't pretend to have expertise you lack, and people
will knock themselves out trying to explain things to you.

Not everyone is completely convinced by Jobst's book: the
evidence is clear, but people often lack a conceptual
framework to make sense of it. Thinking about how the bottom
of the wheel would transmit force to a top spoke is usually
the key.

To answer your question:
It takes force to deform a structure. The force downward on
the hub is transmitted via the spokes into a force downward
on the ground by the rim. Adding the tire doesn't change
the analysis much, so ignore it.

: The actual bottom spokes (where the wheel is flattened) does not support,

<Sigh> Fine. Think of the wheel as "hanging" from the top spokes
because they are under more tension than the bottom spokes.
That really sidesteps the issue: The key discussion point is
how the wheel changes from it's rest state (no one on the bike).
The tension in the top spokes does not increase significantly
compared to the tension decrease in the bottom spokes. This
contrasts with the previous claim that the tension in the top
spokes increases roughly the same as the bottom spoke decrease,
which is demonstrably incorrect.

: As the wheel deforms, part of it gets closer to the hub

Look up the terms yield and buckle in a decent engineering book.

The mechanisms that cause spokes to pull through rims are
a side issue. Spoke tension doesn't increase significantly
when someone gets on a bike; it decreases. When the bottom
spokes are unloaded (as the bike moves and they become side
spokes), those spokes pull harder on the rim than when they
were on the bottom. Those continual changes in stress (re-loading
spokes to their pre-stressed level) is what leads to failure.

: Spokes support by tension as the wheel deforms and goes out of

Your Model #2.
The increase in tension of other spokes is not significant
compared to the change in tension in the bottom 3-4 spokes.
Those spokes are compressed from their pre-stressed state,
and the rest of the wheel stays essentially the same. For
the purpose of analyzing the structure, the bottom spokes
are compressed (from their pre-stressed state) and the
rest stay essentially the same.

On a semantic note, you shouldn't use "evidenced" unless
you actually have evidence, which you don't. But I digress...

: I stand corrected on my assertion that the hub "hangs", but

They aren't close to slack (unless the wheel is shoddily built).
They are compressed somewhat from their pre-stressed state.
If they go slack, the wheel feels loose and wobbly: the bottom
of the wheel has no lateral support. Here's something of a
conceptual challenge: when part of a structure is pre-stressed
like a spoke, it can be "compressed" for the purposes of
analyzing the structure. Your (inaccurate) idea that side
spokes change is something to check with a full mathematical
model and experimental data. The result: the bottom 3-4 spokes
change significantly and the rest don't.

: If I had paid more attention during the vector analysis stuff, I

I doubt that would have made a difference. I once discussed this
issue for weeks with the person in the next office over, and I'm
quite certain he has no difficulty with vectors. Besides, I think
you've described your conceptual model clearly enough. It is (at
first) difficult to analyze pre-stressed structures; it takes
some hard thinking. As a personal test, see if you can explain
pre-stressed concrete to yourself: in what way is it pre-stressed
and why is that an important structural advantage?

David Olson
dao...@mtu.edu

> Think (logically) for yourself!

> o'clock high.

I see you are a "theoretician" who does not believe in experimental
verification. Would you be good enough to get on your bicycle and
verify what you have just written? The suggestion that others should
think logically is presumptuous at best but in your case it's just
rude, especially when you are so ill informed. Maybe some reading
material would do you some good.

Jobst Brandt <jbr...@hpl.hp.com>

>ri...@ll.mit.edu (James B. Riley) writes:

> [...] you should always wear your
> helmet while hanging your bike from the ceiling, because it
> might explode.

>And have your helmet warranty handy when it does. I'll bet
>the manufacturer will replace it for free.

It would rather discuss the case with my house insurance company -
exploding ceilings - wauh!
Soren

----- Everybody knows whats going wrong
in the world,
----- I dont even know whats going on
in myself.
(matt johnson)