Index Home About Blog
From: (Jobst Brandt)
Subject: Re: Building bombproof wheel
Date: 25 Nov 1997 22:48:56 GMT

Wayne Pein writes:

>>> Can you use the 1.8/1.6 spokes on a hub drilled for 14 ga (2.0mm))
>>> spokes?

>> Yes but it isn't ideal.

> What specifically is not ideal about doing this?

Just visualize what occurs as the hole in which the spoke hangs gets
larger.  The cone of the spoke head will seat in the center of the
hole and the elbow will be in thin air until spoke tension pulls it
against the bottom of the hole.  This brings the spoke to yield stress
as it unbends its elbow.  This stress cannot be stress relieved by
stretching the spoke as usual, because you cannot over bend the elbow.

Fortunately, new spokes are underbent to an obtuse angle to make up
for this.  If the mismatch is bad enough, this is not enough to make
up for the oversized hole.  This is one of the reasons some wheels
keep breaking spokes until thicker spokes are used. This then
unfortunately proves that thicker spokes are less failure prone.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Send me BROKEN SPOKES...
Date: 16 Feb 1999 00:06:16 GMT

Neil Cherry writes:

> I did think that the bag caused the cracks (you've since corrected
> that thought). I am a bit confused by on of your other statements.
> That there was a head problem with DT spokes? (I may have paraphrased
> this wrong). Does this mean that the head breaks only at the head or
> does that include breaks at the elbow?

Heads popping off occurs with some production runs and since I haven't
had the opportunity to observe what changes are made to prevent such
spokes from being shipped, I don't know any more about it.  I have
experienced sets of spokes that popped off only the head leaving
behind an intact elbow.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Touring wheel
Date: 2 Mar 2000 22:58:19 GMT

Jay Beattie writes:

> Wouldn't the DT Competition 2.0/1.8 be a better choice for a 36 hole
> wheel for loaded touring?  If not, why [not]?

Well lets turn that around.  Why would 2.0/1.8 spokes be better then
1.8/1.6mm diameter spokes?  I already mentioned that all the spokes
that DT lists are strong enough so what makes you ask?  I, for one, am
not a lightweight and have been riding the same spokes for more than
200,000 miles touring on smooth pavement, cobbles, dirt roads and
trails.  The spoke failures I have had were primarily ones from a
foreign object in the spokes or a dropped chain from a twig in the
derailleur while trail riding.

The idea that spokes are not strong enough is based on failures of
spokes that were not stress relieved after building the wheel.  For
wheel builders who cannot understand the concept and refuse to take it
on faith, thick spokes are the only answer... this in spite of many
failures among 2.0mm diameter straight gauge spokes.  That's why we
have 2.34mm diameter spokes and on the other end, "Revolution" spokes.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Touring wheel
Date: 4 Mar 2000 01:51:56 GMT

Eric Salathe writes:

>> As I said, the thinnest spokes DT sells is more than strong enough
>> for the task....  There is a whole book [by Jobst Brandt] on the
>> subject that you would probably find interesting....

>> "How to Select Components" section does not even mention a
>> particular gauge as being adequate or in adequate -- or even
>> recommended.

> My reading as well. I had no idea that a 1.8-1.6-1.8 DT Competition
> spoke was a good idea after reading The Bicycle Wheel, only on
> seeing it mentioned here.

I think that comes from looking for a table of which spokes to use
where.  The text explains at length why thin spokes are preferable and
that they are only subjected to reduction in tension in use, the wheel
being a prestressed structure.

> Furthermore, Jobst has derogated the even thinner 1.8-1.5-1.8
> Revolution spokes, relative to the Competition.  That does not square
> with the above statement that "the thinnest spokes DT sells is more
> than strong enough for the task.

There is a difference between being strong enough and being easy to
build strong enough.  The question was whether the spokes could
withstand the loads, to which the answer is yes.  I choose not to
build with 2.0-1.5mm spokes because they are torsionally too flexible
to be reasonably tightened, but then that's true for any flat spoke or
even thick spokes on 16 or 12 spoke wheels that must be far tighter to
work reliably.

> " Now perhaps the Revolution is indeed strong enough, but just
> cannot be built into a strong wheel due to windup limitations on
> spoke tension. So we never get a straight answer (or even a butted
> [or should I say swaged] answer).

The straight answer is that the tried and tested 1.8-1.6mm spokes are
the best compromise for most wheels.  If you want to build special
wheels with different spoke complements and unconventional spoke
patterns, you should be your own boss.

> Can it possibly be that 1.8-1.6-1.8 is the magic perfect ratio for all
> cycling applications and that even the slightest perturbation of any of
> the three numbers results in mathematical and engineering absurdity?

It was until 400 gram rims became old hat and 36 spoke for road
wheels went out in favor of 30 or 16 or some other short lived layout.

> We have 48 2.0mm straight-gauge 5-cross spokes on each wheel of our
> touring tandem. The wheels bear 375 lbs or so of bike, people, and
> gear on dirt roads. I see no basis to reconsider that choice and
> have the hassle of spoke windup and expense of buying 100 new spokes
> for some purely theoretical advantage. The spokes have outlived
> several rims -- they will do not break.

That's the best kind.  Don't throw them away, because all the spokes
that are going to break are gone.

> The reliability of a wheel is only weakly related to the choice of
> spokes, within the reasonable options.  Let's not make more of it
> than there is.  This is like arguing the weight benefits of a
> titanium cassette -- a trivial effect.  Stress relieving on the
> other hand, I am convinced, is not trivial and significantly reduces
> the likelihood of broken spokes.

You mean weakly related to the spoke cross section, not the brand of spoke.
The top spoke brands use excellent wire and generally form them well, but
even these have some poor quality from tool wear and lack of adjustment.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Touring wheel
Date: 4 Mar 2000 01:35:21 GMT

someone writes:

> "The Bicycle Wheel," p. 81, 3rd Edition:

> "With a standard 36-spoke wheel, 1.8 diameter spokes are preferred
> because they are sufficiently strong and give better stress
> distribution.  With a good rim, 1.8 mm spokes are appropriate for
> riders that weigh up to 85 kg.  For wheels with fewer than 36
> spokes, 2.0 diameter is the preferred size.  In either size, swaged
> spokes are better if time and expense permits their use."

That may have been good advice originally but today, spokes are
stronger than when that was written and have better fatigue
characteristics.  Since that was written, spokes have lasted
indefinitely with far higher tension (fewer spokes) that was
previously possible.  Future editions will reflect that advance.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Touring wheel
Date: 4 Mar 2000 01:27:21 GMT

Mark McMaster writes:

> Okay, so 1.8/1.6/1.8 spokes are more than strong enough for 36 spoke
> wheels.  What about special purpose wheels with fewer spokes?  Would
> a wheel with 20 or 24 spokes be better served with 2.0/1.8/2.0 spokes?

That depends on the rim.  If it is a deep section aero rim, you would
exceed the torsional resistance of the spoke before tension reached the
limit of the rim, the feature that is usually the indicator of maximum
tension.  You can probably not over-tighten a swaged spoke 1.8 or
2.0mm anyway, because the threads bind up before that.  It was my
experience with 1.8-1.6mm spokes on 24-spoke track wheels that getting
them tight required unloading the spoke by side force to turn the
nipple on the spoke.  Without that, the spoke would wring its neck and
break from torsion.

You'll understand from that why people don't build 12 and 16 spoke
wheels in their spare time.  It requires special equipment to tighten
spokes tight enough (16 spokes about twice as tight as 32) for the
same load carrying ability.  These spokes are generally not twice as
great in cross section.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Touring wheel
Date: 5 Mar 2000 20:31:29 GMT

Ed Chait writes:

> I may be wrong here, but in the interest of honoring copyright laws, it
> would probably be a good idea to ask Jobst if he minds before posting
> sections of his book here.  Even if they are pertinent to the discussion.

I'm not sure what the laws state but copyright laws are intended to
protect reprinting for the purpose of denying the author of due
compensation and undermining his distribution of the text.  I don't
find that citing sections of text with attribution infringe.  This is
much like book reviewers who cite passages from works that they

As I said to this subject earlier, the section needs an update to
reflect the state of the art in spokes.  At the time of writing,
reasonably durable spokes were just becoming the norm.  Prior to that
time, none of us would think of a long weekend ride without taking
along spare spokes.  I haven't don that in many years although I take
spokes along on alpine tours because road hazards can easily break a
spoke.  Even here, I get a stick in the spokes occasionally.
Currently one of my rear spokes has a visible kink from such an
encounter.  I'll get around to straightening it and do a bit of
adjusting soon.

I have used 1.8-1.6 DT spokes for many years, the same ones, the same
wheels but with several generations of rims.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Straight-pull spoked wheels snapping spokes
Date: 27 Mar 2000 19:17:45 GMT

Damon Rinard writes:

>> They are breaking at the point which is supposed to be the
>> advantage of a straight pull spoke so I figure they have a stress
>> concentration at that location.

> You bet they do. It's the sudden change in cross section between the
> spoke shaft and the spoke head.

>> Maybe a manufacturing/engineering problem with the forming of the
>> head.

> You bet it is. Residual stresses from forming the head.

It's probably that but more importantly, structure in the head is
about as unpredictable as crushing paper.  Grain alignment in drawn
wire is longitudinal and cold forming a head onto the end of a wire
disturbs this uniform structure.  That is the main reason why this is
the weakest place on a spoke.  The elbowed spoke does not pull
directly on the head, and therefore, transfers most of its load to the
flange by a stronger part of the spoke.

> See for an artist's rendering and an
> explanation.

* Velomax eliminates this work hardened head by threading the spokes
* directly into the hub.  It's a simple, elegant solution to an age
* old problem - but it's based on sound engineering principles.

This is an even older solution that has its own problems both with
spoke failure and spoke thread extraction.  Spoke threads are full of
residual stress that results in failures even with swaged spokes if
not adequately stress relieved.  Even then, the reduction in cross
section causes a stress concentration that can initiate cracks.  When
such a spoke fails, it often fails several thread inside the hub, that
being the place where load transfer takes place.  Spoke extraction is a
difficult problem in such a failure.  That is one reason why these
hubs vanished with high wheel bicycles, the other is that one damaged
thread ruins the entire hub.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Any problems with new style spokes
Date: 11 Sep 2000 18:47:06 GMT

Roger Musson writes:

> Earlier this year the spoke manufacturers DT and Sapim (and possibly
> other manufacturers) changed the profile of their spoke elbows at the
> request of hub manufacturers who were making thicker flanged hubs. The
> new profile spokes have longer elbows. For DT spokes the new profile
> spokes are designated (R1) on the packaging.

> This is fine for thick flanged hubs but I have experienced problems
> with them built into standard hubs (i.e. the vast majority of
> available hubs). Typically after a few gentle rides the wheel goes out
> of true. This never happend before. The wheels are built the same as
> previous ( to the procedures outlined in the Bicycle Wheel) and the
> only variable to change is the spoke.

Oh no, they've done it again, a solution for a non existing problem.
Flanges have been 3mm (aka 1/8") for a long time and survived just fine.
Who are these people anyway.

The reason you can keep on tightening is that the elbow overstand is
straightening out, something it shouldn't do if the crook angle is
obtuse as it should be.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Any problems with new style spokes
Date: 12 Sep 2000 19:05:46 GMT

Roger Musson writes:

>>> Earlier this year the spoke manufacturers DT and Sapim (and
>>> possibly other manufacturers) changed the profile of their spoke
>>> elbows at the request of hub manufacturers who were making thicker
>>> flanged hubs. The new profile spokes have longer elbows. For DT
>>> spokes the new profile spokes are designated (R1) on the
>>> packaging.

>> Oh no, they've done it again, a solution for a non existing
>> problem.  Flanges have been 3mm (aka 1/8") for a long time and
>> survived just fine.  Who are these people anyway.

> Campagnolo have lots of influence.

>> The reason you can keep on tightening is that the elbow overstand
>> is straightening out, something it shouldn't do if the crook angle
>> is obtuse as it should be.

> The angle on the newer spokes is 90 degrees.

Now I know I should not have explained why the crook should have an
obtuse angle in "the Bicycle Wheel".  These guys go to great lengths
to show they don't believe in scientific analysis of structural

> My main concern is that these wheels quickly lose some truness and I'm
> not sure what to do.

I don't understand that.  This implies that your wheels are
experiencing yield in the spokes or that the spokes are not tight
enough.  The first problem should be resolved by stress relieving and
the second through proper tensioning.  In spite of all that, with 90
degree spoke elbows, you may get spoke failures on the inbound spokes,
but that shouldn't show up right away.

Jobst Brandt      <>

From: (Jobst Brandt)
Newsgroups: rec.bicycles.misc,
Subject: Re: Breaking spokes on 2000 Schwinn Super Sport
Date: 21 Oct 2000 21:44:03 GMT

Annie Crawford writes:

>> Thing is, I wonder about this particular case.  Unless the spokes
>> that are breaking are all the same length, they couldn't have come
>> from the same batch.

> I thought that huge quantities of spokes started out the same length
> and were then cut to various lengths and then threaded.  This would
> mean any length could be from the same batch as another length.

That might be possible but threads are rolled onto the spoke before
the elbow is bent.  Handling spokes by machine becomes substantially
more difficult once the elbow is made.  That doesn't mean that the
swaging machine is adapted to each length, a length that is cut after
this process.  So because the swaged portions are the same for several
lengths does not mean that the length was made on the finished spoke
and then threaded.  Just the same, your point could be taken a step
farther back, to the wire spool.  Various lengths are made from the
same spool.

>  And I did think that we were talking about "bad spokes."  It sounds like
> several Super Sports, not all the same model, not all bought in the same
> shop, are having the same problem.  And don't quote me, but somebody at
> Schwinn has admitted to spec'ing less expensive Taiwanese spokes on these
> bikes.

Let's not link any nation with certain quality.  Your statement reads
a lot better and convincing if you leave out the national reference.
More accurate, would be to clarify whether these are stainless,
chromed, or galvanized spokes.

> If spoke quality was not an element in the equation, DT and
> Wheelsmith wouldn't be getting such good prices for their spokes.
> True?

Not necessarily.  Their spokes are known to break as well if the wheel
is poorly built.  Quality is compromised if the thread dies are not
new and the head forming die is not correctly adjusted or worn.  Spoke
heads sometimes have the cap misaligned with the cone, causing flash
on one side.  If you look at the emblem on the head, you can easily
see how worn the die is.  If the mark is indistinct, the die needs
replacement.  The same goes for a thread rolling die if it develops a
chip.  These problems result in crack initiation defects in the spoke.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: Wheel building suggestions for a 200lb rider
Date: 21 Oct 2000 23:01:08 GMT

Kevin Munday writes:

> You'd recommend 28h/32h for a "big boy"?!  Remember, this guy's
> about 200 lbs....  Why not 32h/36h?

The concept of fewer spokes in the front than in the rear is misplaced
unless only riding around the block, so to speak.  When descending and
braking hard, the front wheel carries the entire weight, rider and
bike.  When climbing standing the front wheel carries most of the
riders weight but at an angle that is enough to slacken spokes, as we
hear when spoke twist of a poorly built wheel goes tinkle tinkle.  On
rough stuff, like washboard, and descending, I would feel stupid for
putting fewer spokes in the front than I thought were needed in the

As it is, we have a whole generation of riders with too few spokes ala
Rolf or Shamal, and riders who think it normal to have their wheels in
for repair after a few hundred miles, a perception should not be
considered normal.  Their wheels cannot be ridden if one spoke fails
so the cell phone or follow car is essential.  On the other hand many
don't ride that far from the shop anyway.

Why do riders think fewer than 36 spokes is a good idea?  It can't be
that they are attempting world records, unless they are fantasizing.
Unless people build good wheels with a full complement of spokes, I'm
afraid the 36 spoke rim may go the way of many other useful bicycle
components.  On the other hand it may be like the convertible car,
that was declared a thing of the past 10 years ago, only to return a
few years later and is again in full swing now.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: DT spokes changing?
Date: 1 Nov 2000 01:45:02 GMT

Jeffrey L. Bell writes:

> I came across this page about changes in the design of DT spokes.


> Is this change significant?

Yes, and it together with flange holes being 2.4mm in diameter, makes
building a durable wheel difficult.  Stock up on old spokes now!

I see the thicker flange as a response to 16-spoke wheels that are all
the rage these days and on which much money is spent.  These don't work
well with 3mm thick aluminum flanges especially with radial or near
radial spoking.  SO what do we do?  Well, we don't do something
reasonable, we go to thicker spokes and flanges, and still have an
unreliable wheel.

Jobst Brandt      <>

From: (Jobst Brandt)
Subject: Re: DT spokes changing?
Date: 1 Nov 2000 16:44:41 GMT

Helmut Springer writes:

>> Yes, and it together with flange holes being 2.4mm in diameter,
>> makes building a durable wheel difficult.  Stock up on old spokes

> are there alternative vendors regarding quality staying with the
> 'old' configuration?  Prym?

There are several good ones including Wheelsmith, Hoshi, Sapim and others.
I haven't seen what Prym or Berg has to offer these days.

> btw: what diameter are 'normal' flange holes?  I checked both the
>      2000 XT and the 1988 Santé hub I happen to have lying around
>      and both have 2,5mm holes.

They should be as small as the spoke threads can pass through, or
about 2.1mm for 1.8mm diameter spokes.

Jobst Brandt      <>

Subject: Re: Snaping Spokes
Date: Fri, 21 Sep 2001 03:28:25 GMT

Trevor Jeffrey writes:

>> Zinc plated spokes fell out of favor because of the finish.  Back
>> when Robergel was the most popular spoke their plated Sport model
>> was much stronger than the Three-Star stainless.  When DT began
>> importing higher quality spokes the difference between stainless
>> and plated was narrowed.  Zinc plated spokes still build a stronger
>> wheel but they don't look nearly as nice since the zinc oxidizes
>> and becomes dull and dirty looking.

Plated spokes are no longer used because, exposed to weather, their
threads rust solid, preventing adjustment or reuse.  In this respect I
had my share of plated spokes that broke off at the thread.  There may
be an excuse for chromed spokes for indoor track use where sparkling
wheels at six day races look better than stainless spokes.

> Raleigh used Berg galvanised spokes, 14/15 swg which polished up
> very well, the shine would last the year.  These were more than
> adequate in tensile strength.

Neither of these characteristics are important in comparing spokes
because, as we see today, looks means nothing amongst the ugly wheels
people ride and strength is an illusion because in use, conventional
wheels don't exceed 1/3 their yield stress in1.8-1.6mm diameter spokes.

At normal loading, no spoke should ever break and knowing that spokes
operate at such a low stress is what makes residual stress and stress
relieving a logical target when building wheels.  That is why spokes
last essentially indefinitely once they have been stress relieved or
have failed for lack of it and been replaced by a spoke that is
properly formed and stress relieved.

It is for this reason I encourage people to stay with their spokes
once they have reached a reliable threshold.  Unfortunately, rims go
out of fashion so rapidly that using the same spokes is often not
possible, thanks to fashion.

Jobst Brandt    <>

Subject: Re: Spoke gauges and threads?
Date: Sun, 11 Nov 2001 04:47:10 GMT

Jim Adney writes:

> Over the last 50 years, what spoke gauges and threads have been used
> around the world. I know that there have been at least 2 systems
> with 2 gauges and threads each, but were there more than that? How
> many more?

> I see diameters specified in mm these days, but they used to be
> called out in gauge sizes. Does anyone know which of the various
> gauge standards was used, or were there also several of these?

In my experience there were only 1.8am and 2.0mm diameter threads,
unfortunately both 56TPI.  This makes it possible to build a wheel
with 2.0mm nipples on 1.8mm spokes, and if they are not tightened
much, they seem to fit.  As they are tightened or stress relieved, the
threads pull out with a bang.

> Are the threads standard threads or specific to bicycle spokes?
> Metric or English? 60 degree or 55 degree?

I believe that the 56TPI probably came form the USA in early days of
bicycles, when the bicycle was the leading technology and there were
many great brands that were exported.  Even today Europeans call a
team races "Madison" after Madison Square Garden NY.  Six day racing
was known in Italy as a "Il Grand-Americana" in the days of Alfredo
Binda in whose museum such old posters decorate the hall.

> In other words is there a pattern to this or has it all been a big
> mess? Is it metric and English, or French, English, German, and
> Italian, or ...?

As far as I know there was only one 0.2mm pitch thread offered in the
USA by Robergel (France), who long since went out of business.  When
Wheelsmith first planned to offer spokes, I suggested they use 0.2mm
pitch for 1.8mm spokes and 56TPI for 2.0mm spokes.  They didn't have
the courage to deviant from the norm and subsequently had whole batches
of wheels that someone in their shop had mixed 1.8mm spokes with 2.0mm

There is a reason for the single 56TPI and that is they are threaded
by the same flat thread rolling dies, a weak reason if ever there was
one, manufacture put ahead of use.  Besides, anyone in the business
has many threading machines and dies.

Jobst Brandt    <>

Subject: Re: First Time Wheel Builder
Date: Wed, 19 Dec 2001 19:16:37 GMT

Tom Ace <> writes:

>> Couple of books, the Bicycle wheel by Herr Jobst and the Art of
>> Wheelbuilding by Gerd Schraener(sp?)- We carry the later book.

> Is the latter book as misguided as FAQ that Schraner wrote at ?

> Schraner says spokes at the top of the wheel are loaded when
> the wheel bears weight,

> he says aluminum nipples are okay, and tells you about the
> energy saved by lowering rotating weight (as if the difference
> from using aluminum nipples was actually important),

> and he tells you tying/soldering is good because "the immediate
> spokes taking up the load are relieved by their neighbors" (as if
> this happens any more than it would on an untied, interlaced wheel).

The book was the result of one of my postings to where I
criticized the revolution and 2.34mm diameter spokes.  This infuriated
Mr Zingg who subsequently stopped distributing "the Bicycle Wheel"
German edition ("das Fahrrad-Rad") and the Avocet tensiometer.  This
also gave rise to Schraner's book and the DT tensiometer.  Schraner,
an unwilling accomplice to all this, explains at length in his book
that he is not an engineer before proceeding to tell about the "art"
of wheel building.  The wheel hanging from the top spokes and other
such things are a result of his being pushed into the fray.

The DT FAQ has several interesting items, such as the spoke thread
picture from "the Bicycle Wheel" and the composition of spoke wire:

* What are spokes made of?
* Practically only one material is used for spokes, these days:
* stainless steel.

* The stainless steel used by DT Swiss is made of:
* approx. 18% chrome
* approx 10% nickel
* approx 72% steel and alloying metals

Steel is not an element.  Iron (Fe) is the basis for steel of any
kind.  However, this is further obscured by materials listed under
"Spokes" where (Cr, Ni) is given but not (Fe).  Some of the items,
such as tying and soldering underscore the nature of the book.

In spite of this, DT still probably makes the best spokes available.

Jobst Brandt    <>

Subject: Re: First Time Wheel Builder
Date: Wed, 19 Dec 2001 20:51:36 GMT

Mark M? writes:

> Jobst, would you care to rank a few of the next-best manufacturers?
> Could you quantify how good the best spokes are relatively speaking?
> This has been touched on recently, but not done definitively so far.

I don't know how other spokes perform, only that DT spokes last well
and have a good finish.  Their threads are clean and well formed, and
their brass nipples are well made.

There may be several equally good spokes on the market, but I know
little about the other than what I read here on

Jobst Brandt    <>

Subject: Re: Lacing spokes across plane of wheel
Message-ID: <uHIm9.34057$>
Date: Wed, 02 Oct 2002 20:30:18 GMT

Chalo Colina writes:

> On a related note, I'd like to hear any observations about DT's
> "ProHead" spoke nipples.  Though I've not tried them, I believe they
> have a spherical load bearing surface and may be applicable to these
> wheels (or any other wheels with a high deviation from
> perpendicularity at the spoke nipple).

So I don't know why they make the conical seat spoke nipples at all.
I've always wondered about that.  Even with a small angle to the
eyelet, contact (bearing area) is reduced.

They ought to stop making the old cone-heads and be done with it.

Jobst Brandt  <>  Palo Alto CA

Subject: Re: Snaping Spokes
Date: Thu, 27 Sep 2001 21:00:51 GMT

Phil Holman writes:

>> If the weight actually hung from the upper spokes, the spokes would
>> break as they moved into the LAZ at the top of the wheel.

> For you, the term "hanging from the upper spokes" therefore requires
> a spoke load increase for it to be correct.  The uppermost spoke
> tension pulls down on the rim at one end and transfers from reacting
> lower spoke tension to reacting dropout down force without any
> change in magnitude.  A freebody diagram identifies the load paths
> and whatever way an observer wishes to describe the situation is OK
> as long as they are not confused by the change.

>> Someone who's never thought about a bicycle wheel can understand
>> Jobst's ideas much easier than someone who cut their teeth,
>> figuratively speaking, on the notion that the weight hangs from the
>> upper spokes.

> This is fine until we move into deep-section rims and less spokes.
> This is an unfair comment on my part because it is out of scope with
> the contents of the book. I'm surprised that people have not come
> back to you with reports of their findings on plucking the spokes of
> these types of wheels.

You'll find that the same effects are true.  The four bladed Spinergy

also have tensioned spokes and their mode of failure is loss of
tension, caused by baking wheels in the back of a closed car in direct
sunlight.  The downward spoke of such de-tensioned wheels rattles as
it is slackened by the load and, if the rider does not heed this
warning, collapses in the event of a side load.  I see that some
models have adjustment screws between these blades and the rim, which
seems a logical response to the problem.

Jobst Brandt    <>

Index Home About Blog