Bicycle wheels - how do they work?

Upon the miasma of midnight, a darkling spirit identified as Simon
Brooke <[email hidden]> gently breathed:

Quoted message said:

Beware: this is a profoundly religious argument, which will make helmet
flame wars look like mild disagreements between old friends. In
particular, do not ask this question on rec.bicycles.tech. If you would
like to know what happens if you do, check on google.

I give you warning, the debate gives rise to a lot more heat than light.

<surveys length of thread and multiple branches from a nice safe railway
compartment - shakes head>

Arrghhh!! No! It can't be! :-)

I did try googling, bit only found sites about building wheels, and I'd
no idea it was such a contentious topic - sorry everyone!

Does make a nice change from h*ml*ts though...

NP: Army Of Lovers - Crucified
--
- Pyromancer Stormshadow.
http://www.inkubus-sukkubus.co.uk <-- Pagan Gothic Rock!
http://www.littlematchgirl.co.uk <-- Electronic Metal!
http://www.revival.stormshadow.com <-- The Gothic Revival.

Pyromancer said:

I did try googling, bit only found sites about building wheels,
and I'd no idea it was such a contentious topic - sorry
everyone!

Don't apologise, we may be getting somewhere this time round!

Mind you bicycle wheels do go round a great many times before getting any
where!!!

PK

---

In article said:

[snip, disc wheel construction methods]

Quoted message said:

Spinergy, and HED3 wheels are other examples of 'spoked' wheels where
the 'spokes' are in compression not tension. Eight flat solid plastic
blades in the case of the original spinergy design, and three large
curvy ones in the HED.

Cheers, Andy
www.stirling-tri.co.uk

Ah yes, remind us which is best for cutting off a cyclist's knee cap:-)

--
Jan

James Annan said:

That is indeed pure semantics

No it isn't. Semantics is a branch of linguistics, and is concerned with
the nature of the relationship between words and meaning.

Daniele
--
Apple Juice Ltd
Chapter Arts Centre
Market Road www.apple-juice.co.uk
Cardiff CF5 1QE 029 2019 0140

On Thu, 30 Sep 2004 00:48:10 +0100, "DavidR"

david.nospam.r_a@t_cwcom.net said:

How does a wheel with an infinite number of spokes work, such as on a 2CV?

Differently. As does a cart wheel.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

On Fri, 1 Oct 2004 08:54:05 +0100,

(D.M. Procida) said:

Quoted message said:

That is indeed pure semantics

Quoted message said:

No it isn't. Semantics is a branch of linguistics, and is concerned with
the nature of the relationship between words and meaning.

Er, that's the point, innit? Does a bicycle hub "stand" on a spoke
which would not support its weight if it were not still held in
tension by the rest of the spokes?

My view is that it's an angels-dancing-on-the-head-of-a-pin argument.
There is very little value in describing the behaviour of a complex
structure by reference to one isolated part of the structure which
cannot in practice be isolated.

You end up in the absurd situation where, having "proved" that the hub
"stands" on the lower spokes, you can nevertheless remove the lower
spokes entirely without the hub crashing to the floor, but if you
remove all but the lower spokes the hub *will* crash to the floor.
And indeed the hub "hangs" more with a stiff rim and "stands" more
with a bendy rim. Crazy talk. How does that help to understand
what's going on?

The way I see it is that the wheel is given stability by the
interaction of spokes and rim, that it is stable only by virtue of its
being a complete structure (see how rapidly a wheel fails after the
first spoke goes), that the action of loading the wheel causes the
small section of the rim in contact with the ground to deflect, and
that this leads to almost all the cyclic change in tension being over
a short arc at the bottom of the wheel. This is useful in
understanding spoke and flange fatigue, as well as explaining why
spokes have to be tighter than one might expect, because if spoke
tension ever drops to zero the whole things goes nonlinear and that is
your gateway to a world of pain.

See? We said it was contentious ;-)

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

you know? said:

You end up in the absurd situation where, having "proved" that the hub
"stands" on the lower spokes, you can nevertheless remove the lower
spokes entirely without the hub crashing to the floor,

No, you can't. If you remove the spokes from half teh circumference
of a loaded wheel the hub will crash to the floor, irrespective of
which 180 degrees of circumference you choose. (For useful values of
loaded, crash, and floor.)

Quoted message said:

And indeed the hub "hangs" more with a stiff rim and "stands" more
with a bendy rim. Crazy talk.

No it isn't - it's teh real world, taht's what really happens -
relative stiffness of components affects teh distribution of load in a
structure. I'm not sure why you would say this is crazy - it's simple
fact.

A guyed radio mast subject to wind load, for example, will load the
guys less as you make the mast stiffer, and will load the guys more if
you make the tower more flexible. Is that crazy too? Any statically
indeterminate structure will show similar effects - as you make one
part proportionately stiffer it will tend to attract load.

In the particular case of teh wheel, to get any significant hanging
action, you need to make the rim vastly stiff - a simple doubling or
so doesn't make a great deal of difference.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

[email hidden] wrote in message news:<[email hidden]>...

Quoted message said:

Spinergy, and HED3 wheels are other examples of 'spoked' wheels where
the 'spokes' are in compression not tension. Eight flat solid plastic
blades in the case of the original spinergy design, and three large
curvy ones in the HED.

Not so. The 'spokes' or flat plastic blades in a Spinergy wheel are in
tension, not compression. It's when they lose tension that they
collapse. In this sense at least the Spinergy is a conventional
bicycle wheel.

--
Dave...

Andy Dingley said:

Zog The Undeniable said:

Over-tight wheels are most
likely to pringle/taco,

I disagree with that.

I don't. I've pringled wheels all too easily. Just tighten your spokes
as much as possible and hit a few potholes to see for yourself. I've had
better luck since rebuilding with lower tension. The tension is still
quite high but hopefully with enough of an anti-pringle margin.

Quoted message said:

It's true for radial impacts, but not for sideways forces. For typical
cycling (hairy-arsed MTB anyway, maybe not for you skinny
road-lizards) and the typical combination of impact / likely wheel
tensioning errors, it's the sideways hits on sloppy wheels that cause
problems, not the highly-strung ones.

Road wheels don't really get sideways hits... well, unless you get hit
from the side :-) Big bad holes and bumps in the roads cause the common
excessive (radial) forces.

~PB

in message <[email hidden]>, PK

(') said:

Pyromancer said:

I did try googling, bit only found sites about building wheels,
and I'd no idea it was such a contentious topic - sorry
everyone!

Don't apologise, we may be getting somewhere this time round!

We won't, because the argument is essentially meaningless. We all agree
about what actually happens (viz: all spokes remain in tension all the
time, but the tension in the spokes immediately above the contact patch
and a little on either side of it is less than the tension in the other
spokes). However, the TRUE BELIEVERS (all bow down before the holy
works of Saint Jobst) insist that this means the wheel 'stands on' the
bottom spokes, and the rest of us look on in bemusement at such absurd
linguistic gymnastics.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

The Conservative Party now has the support of a smaller proportion of
the electorate in Scotland than Sinn Fein have in Northern Ireland.

in message <[email hidden]>,

(') said:

Quoted message said:

DavidR wrote:
That's interesting. I thought bicycle disc wheels were spoked wheels

with

Quoted message said:

covers. Something learnt.

Quoted message said:

How is it made? Is it 4 pieces of CF (hub, rim & 2 cones) bonded

together

Some disc wheels are covered spoked wheels, notably the wheel upon
which a certain David Millar rode to, erm victory at the 2003 worlds.

I thought such wheels were banned under UCI rules, and that the disks of
disk wheels had (by rule) to be structural?

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; For in much wisdom is much grief; and he that increaseth
;; knowledge increaseth sorrow.." - Ecclesiastes 1:18

Ian Smith said:

Quoted message said:

You end up in the absurd situation where, having "proved" that the hub
"stands" on the lower spokes, you can nevertheless remove the lower
spokes entirely without the hub crashing to the floor,

Quoted message said:

No, you can't. If you remove the spokes from half teh circumference
of a loaded wheel the hub will crash to the floor,

Er, except that the FEA shows that the spokes experiencing the change
in tension are through about a 30 degree arc at the bottom. So you
can.

Quoted message said:

Quoted message said:

And indeed the hub "hangs" more with a stiff rim and "stands" more
with a bendy rim. Crazy talk.

Quoted message said:

No it isn't - it's teh real world, taht's what really happens -
relative stiffness of components affects teh distribution of load in a
structure. I'm not sure why you would say this is crazy - it's simple
fact.

I'm not disputing the way the wheel works, just the use of words like
"hang" and "stand" to describe the forces on individual components in
isolation, when those components do not - and cannot - support the
load in the same way in isolation.

It's like saying I can stand on a piece of string provided there is a
system in place which keeps the piece of string in tension - a
statement which, although undoubtedly true, is entirely pointless; it
tells us nothing about the properties of string or of the system which
must exist to hold it in tension.

As soon as you start using words like hang or stand you have to
explain how you can remove the spoke which is apparently doing all the
work, but not the ones which aren't; and how if you place the wheel on
a compliant surface, the hub suddenly stops standing on the bottom
spokes. At which point you are back to describing the entire
structure and how it works in the round [sorry], which is clearly what
you should have been doing in the first place rather than relying on
simplistic descriptions which raise more questions than they provide
answers. It is not so hard to understand the actual situation that
oversimplification is called for, after all. Once you realise that
the bottom of the rim deflects slightly, everything else falls into
place neatly.

We have been round this loop endless times. You know my views and I
know yours and I don't suppose either of us is in any danger of
changing them at this point, new evidence being conspicuous by its
absence.

The funny thing being, we both we both completely agree on how the
wheel works and why the change in tension is most evident in the
bottom few spokes :-)

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

On 1/10/04 10:32 am, in article [email hidden], "Ian

Smith said:

you know? said:

You end up in the absurd situation where, having "proved" that the hub
"stands" on the lower spokes, you can nevertheless remove the lower
spokes entirely without the hub crashing to the floor,

No, you can't. If you remove the spokes from half teh circumference
of a loaded wheel the hub will crash to the floor, irrespective of
which 180 degrees of circumference you choose. (For useful values of
loaded, crash, and floor.)

Only if that 180 degrees is contiguous. If you removed every second pair of
spokes (for a radial spoked wheel) it would still work..

...d

On Thu, 30 Sep 2004 22:40:27 +0100, Jon Senior

jon_AT_restlesslemon_DOTco_DOT_uk said:

Quoted message said:

The goff revival comes third on the list.

I would have thought that the last thing the world needs is a thread
arguing about the manner in which a spoked wheel supports a load!

That or one about helmets.

Should cybergoths wear helmets, to go with their ubiquitous scalp
goggles ?

Should cybergoths wear b*bshorts, to stop trads ramming their
glowstick where the sun don't shine ?

In article said:

D.M. Procida said:

Imagine you built a bicycle wheel, but instead of spokes you used brake
cables, which you somehow managed to tension so that they held the rim
in a neat circle, and the hub in its centre.

Would it work?

Yes, and it was sold by someone-or-other called something-or-other and
used a mesh of kevlar fibres between spoke positions. There were
strands from rim to hub, but also from rim to elsewhere on teh rim,
and teh whole effect looked a bit like those 70s things where you made
a picture of an owl by running thread around little pins hammered into
a wooden board.

I had one of them (a 70s picture of an owl like that, not a wheel like
that).

I gather there are also more conventional "emergency" kevlar spokes used
on normal rims and hubs in the same place as normal spokes, but which
can be rolled up when not being used (and threaded into place on any
hub hole without having to undo other spokes).

D.M. Procida said:

Simon Brooke said:

No, it's halfway to a religion, being both untrue and completely beside
the point; although I grant you that any untruth believed fervently
enough can be comforting to the believer. No spoke in any conventional
wire spoked bicycle wheel is ever in compression.

That's what I thought, until I started reading this thread. But if
that's true, that spokes are only in tension and not in compression,
then to say that anything stands on any of the spokes has to be false.

Maybe you could read some more of the thread, or some of its previous
versions, to avoid another needless repeat of that part of the argument.

Just zis Guy said:

Quoted message said:

Quoted message said:

That is indeed pure semantics

Quoted message said:

No it isn't. Semantics is a branch of linguistics, and is concerned with
the nature of the relationship between words and meaning.

Er, that's the point, innit?

No, it isn't. I know what semantics is, I used to teach it at
university. It's a subject of academic study, like logic or
epistemology. "Semantics" does not mean "pedantry" or "quibbling about
meanings".

I will be extremely boring and off-topic about semantics if forced to.

Daniele
--
Apple Juice Ltd
Chapter Arts Centre
Market Road www.apple-juice.co.uk
Cardiff CF5 1QE 029 2019 0140

D.M. Procida said:

Just zis Guy said:

Quoted message said:

> That is indeed pure semantics

Quoted message said:

No it isn't. Semantics is a branch of linguistics, and is concerned

with

Quoted message said:

the nature of the relationship between words and meaning.

Er, that's the point, innit?

No, it isn't. I know what semantics is, I used to teach it at
university. It's a subject of academic study, like logic or
epistemology. "Semantics" does not mean "pedantry" or "quibbling about
meanings".

I have do doubt that semantics is an area of academic study just as logic
is. But, those of us not involved in the study of semantics or logic use
those words less tightly than academics might. Chambers, for one, allows
semantics to mean "differences in and shades of meaning of words." For
many of us that looser definition is, by usage, what we mean.

Colin

"PK" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

In summary:

The load is carried neither by hanging from nor standing on spokes. Rather,
the nature of a pretensioned wheel is such that loading the hub reduces the
tension in the lower spokes with minimal changes either in rim compression
or in the tension of other spokes.

Regardless of how you got there, ISTR that this was basically Guy's
position. I'm sure he'll correct me if I'm wrong.

--
Dave...

[email hidden] (D.M. Procida) wrote in message news:<[email hidden]>...

Quoted message said:

That's what I thought, until I started reading this thread. But if
that's true, that spokes are only in tension and not in compression,
then to say that anything stands on any of the spokes has to be false.

No, it doesn't /have/ to be false. Tension and compression are
opposite vectors. Increase one and you decrease the other. A spoke
already under tension is able to support a compressive load by a
reduction in its tension. Reduction in tension = increase in
compression. This and the counter-arguments to it have been stated
many times both here and in rbt. Have a Google for them.

--
Dave...