Breaking Spokes

Bob Mc B said:

Quoted message said:

Quoted message said:

Not true. I ruined two 36 spoke rims by riding them home.

Quoted message said:

Quoted message said:

You did? Details please.

Quoted message said:

Yes.

Yes what?

Jobst Brandt
[email hidden]

Roger Zoul said:

Thinking back on it, I supposed that the second spoke popping could
have been the result of the two spills I had on Saturday, but given
the fact that the lady apparently (and I see this only because I saw
lateral movement and she saw radial movement while spinning the
wheel -- which resulted in her working on it some more) did not do a
good job truing the wheel, I'm not so certain.

That should not compromise spoke life although it might damage the rim
so that it cannot be made as true as a new one, or maybe not at all if
it was collapsed, but that should not affect spoke life. Spoke life
is shortened by not stress relieving and from kinks caused by foreign
objects against them to cause kinks. Even smooth bends have
practically no effect on spoke life. Replacement spokes must often be
bent to insert them into the hub. The main thing is to stress relieve
them after truing. That's what assures durability for high quality
spokes.

Jobst Brandt
[email hidden]

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

Quoted message said:

Bob Mc B said:

How did you assess the abilities of these shops and their

understanding of wheelbuilding and what causes spoke failures? Just
pleasantly talking to a person does not reveal their ability. Certain
questions need to be answered to discover that.

Funny you should ask. In the New Hampshire Seacoast area I asked riders for
recommendations for a good shop. I went to three shops to explain my
situation with breaking rear wheels spokes and asked for their
recommendations. I also asked them "if I didn't have the wheel built at
their shop, who should I get to build it?" Two of the shops recommended the
third so I had the wheel built at that shop.

Bob Mc B said:

Quoted message said:

How did you assess the abilities of these shops and their
understanding of wheelbuilding and what causes spoke failures?
Just pleasantly talking to a person does not reveal their ability.
Certain questions need to be answered to discover that.

Quoted message said:

Funny you should ask. In the New Hampshire Seacoast area I asked
riders for recommendations for a good shop. I went to three shops
to explain my situation with breaking rear wheels spokes and asked
for their recommendations. I also asked them "if I didn't have the
wheel built at their shop, whom I should get to build it?" Two of
the shops recommended the third so I had the wheel built at that
shop.

That sounds odd. But as I said, you could build your own and be
better off in two ways. You can build wheels as well and better than
most shops and you would become independent of them for repairs, much
like bicycle riders who can fix their own flat tires.

http://tinyurl.com/2zxeh

Jobst Brandt
[email hidden]

In article <[email hidden]>, "Roger Zoul"

Quoted message said:

Okay....so I can replace the rear wheel and keep the same front wheel (I
can't see why not)? That might help cashflow...

If it's holding up why not? I would.

Tom Gibb <[email hidden]>

In article <[email hidden]>, "ZeeExSixAre"

Quoted message said:

Quoted message said:

The owner of the LBS told me today that she thinks I ride up hills in

She? That was the problem. Girls don't know bikes!

Brace yourself.

Quoted message said:

Quoted message said:

too high a gear, and doing so puts a lot of stress on the rear wheel.

Cranking in the lower gears puts MORE torque on the wheel, not less.

At the same speed and vehicle weight is there going to be a torque difference
on the rear wheel as a result of using different gears? I doubt it. There
will be a difference on the pedals, but the wheel?

Tom Gibb <[email hidden]>

Quoted message said:

In article <[email hidden]>, "ZeeExSixAre"

Quoted message said:

Quoted message said:

The owner of the LBS told me today that she thinks I ride up hills in

She? That was the problem. Girls don't know bikes!

Brace yourself.

Quoted message said:

Quoted message said:

too high a gear, and doing so puts a lot of stress on the rear wheel.

Cranking in the lower gears puts MORE torque on the wheel, not less.

At the same speed and vehicle weight is there going to be a torque
difference on the rear wheel as a result of using different gears? I
doubt it. There will be a difference on the pedals, but the wheel?

The torque for a given slope (and friction...) depends only on the speed at
a given instant. In a lower gear, there is generally a larger variability
in the speed over a single crank rotation, so the peak torque is higher.
If you pedaled perfectly smoothly, there would be no difference in torque
on the rear wheel.

--
Benjamin Lewis

Gravity brings me down.

Tom Gibb said:

Quoted message said:

Quoted message said:

The owner of the LBS told me today that she thinks I ride up hills
in

Quoted message said:

Quoted message said:

Quoted message said:

too high a gear, and doing so puts a lot of stress on the rear
wheel.

Quoted message said:

Quoted message said:

Cranking in the lower gears puts MORE torque on the wheel, not less.

Quoted message said:

At the same speed and vehicle weight is there going to be a torque
difference on the rear wheel as a result of using different gears?
I doubt it. There will be a difference on the pedals, but the
wheel?

The higher the gear, the smoother the torque although there probably
isn't a significant difference. Just the same, torque is not a major
load for spokes, the effect being distributed mostly among all the
right side spokes (pushing and pulling). For a 36-spoke wheel that is
18 spokes. You can see the magnitude of tension change in "the
Bicycle Wheel" and notice that it is insignificant with respect to
tension cycles caused by supporting the rider.

The upshot is that the bicycle shop is ill informed about wheels.

Jobst Brandt
[email hidden]

Benjamin Lewis said:

Quoted message said:

Quoted message said:

> too high a gear, and doing so puts a lot of stress on the rear
> wheel.

Quoted message said:

Quoted message said:

Quoted message said:

Cranking in the lower gears puts MORE torque on the wheel, not
less.

Quoted message said:

Quoted message said:

At the same speed and vehicle weight is there going to be a torque
difference on the rear wheel as a result of using different gears?
I doubt it. There will be a difference on the pedals, but the
wheel?

Quoted message said:

The torque for a given slope (and friction...) depends only on the
speed at a given instant. In a lower gear, there is generally a
larger variability in the speed over a single crank rotation, so the
peak torque is higher. If you pedaled perfectly smoothly, there
would be no difference in torque on the rear wheel.

Well stated. That is what I was trying to articulate. Besides that,
torque is essentially the same whether riding slowly or faster on a
hill with speeds below about 15mph where wind drag is unimportant. A
rider uses more power (a higher rate) but torque remains the same.

Jobst Brandt
[email hidden]

ZeeExSixAre said:

Quoted message said:

The owner of the LBS told me today that she thinks I ride up hills in

She? That was the problem. Girls don't know bikes!

Quoted message said:

too high a gear, and doing so puts a lot of stress on the rear wheel.

Cranking in the lower gears puts MORE torque on the wheel, not less.

Despite the inane joke, he's right about lower gear putting more torque on
the wheel.

--

David L. Johnson

__o | When you are up to your ass in alligators, it's hard to remember
_`\(,_ | that your initial objective was to drain the swamp. -- LBJ
(_)/ (_) |

TBGibb said:

At the same speed and vehicle weight is there going to be a torque difference
on the rear wheel as a result of using different gears? I doubt it. There
will be a difference on the pedals, but the wheel?

At the same speed, obviously the torque would be the same, seeing as how
that is what is maintaining the speed. But a given rider can put more
torque on the wheel in a lower gear than in a higher gear.

--

David L. Johnson

__o | A mathematician is a machine for turning coffee into theorems.
_`\(,_ | -- Paul Erdos
(_)/ (_) |

Quoted message said:

Roger Zoul said:

Thinking back on it, I supposed that the second spoke popping could
have been the result of the two spills I had on Saturday, but given
the fact that the lady apparently (and I see this only because I saw
lateral movement and she saw radial movement while spinning the
wheel -- which resulted in her working on it some more) did not do a
good job truing the wheel, I'm not so certain.

That should not compromise spoke life although it might damage the rim
so that it cannot be made as true as a new one, or maybe not at all if
it was collapsed, but that should not affect spoke life. Spoke life
is shortened by not stress relieving and from kinks caused by foreign
objects against them to cause kinks.

it's not the just kink, it's the stress riser caused by a sharp object
damaging the surface on impact. if just a kink was sufficient, every
crossed spoke would fail, as would every "corrected line" spoke that you
advocate.

Quoted message said:

Even smooth bends have
practically no effect on spoke life. Replacement spokes must often be
bent to insert them into the hub. The main thing is to stress relieve
them after truing. That's what assures durability for high quality
spokes.

interesting qualification - that high quality spokes assure durability.
can it therefore be inferred that you don't feel confident that "stress
relief" has the same magical properties of infinite fatigue life on poor
quality spokes? if so, what would be the differentiator?

it's interesting how you're so very careful with your claims; when
challenged you fall back on your personal use of just one brand of top
quality spoke, as if it were proof across the whole mechanical/materials
spectrum.

Quoted message said:

Jobst Brandt
[email hidden]

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

Quoted message said:

Bob Mc B said:

Quoted message said:

> Not true. I ruined two 36 spoke rims by riding them home.

Quoted message said:

Quoted message said:

You did? Details please.

Quoted message said:

Yes.

Yes what?

Jobst Brandt
[email hidden]

You edited the message wrong. It went like this:

But how do you "ruin" the rim? Did it become impossible to

Quoted message said:

true after?

Yes.

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

Quoted message said:

Bob Mc B said:

Quoted message said:

How did you assess the abilities of these shops and their
understanding of wheelbuilding and what causes spoke failures?
Just pleasantly talking to a person does not reveal their ability.
Certain questions need to be answered to discover that.

Quoted message said:

Funny you should ask. In the New Hampshire Seacoast area I asked
riders for recommendations for a good shop. I went to three shops
to explain my situation with breaking rear wheels spokes and asked
for their recommendations. I also asked them "if I didn't have the
wheel built at their shop, whom I should get to build it?" Two of
the shops recommended the third so I had the wheel built at that
shop.

That sounds odd. But as I said, you could build your own and be
better off in two ways. You can build wheels as well and better than
most shops and you would become independent of them for repairs, much
like bicycle riders who can fix their own flat tires.

http://tinyurl.com/2zxeh

Jobst Brandt
[email hidden]

Of course I could learn to build a great wheel, but I would rather spend my
free time riding and I think that you missed my major point. I tried really
hard, many times, to purchase a reliable hand built 36 spoke rear wheel.
The longest any of them lasted was under 500 miles! I purchased a "wheel in
a box" and have had wonderful results for over 1500 miles. The advice that
is constantly voiced in this group is that hand built wheels are better, but
there are at least two heavy riders who have had great results with the
Mavic Ksyrium Elite rear wheels.

Old Crow or was it Wild Turkey said:

Quoted message said:

Quoted message said:

Thinking back on it, I supposed that the second spoke popping
could have been the result of the two spills I had on Saturday,
but given the fact that the lady apparently (and I see this only
because I saw lateral movement and she saw radial movement while
spinning the wheel -- which resulted in her working on it some
more) did not do a good job truing the wheel, I'm not so certain.

Quoted message said:

Quoted message said:

That should not compromise spoke life although it might damage the
rim so that it cannot be made as true as a new one, or maybe not at
all if it was collapsed, but that should not affect spoke life.
Spoke life is shortened by not stress relieving and from kinks
caused by foreign objects against them to cause kinks.

Quoted message said:

It's not the just kink, it's the stress riser caused by a sharp
object damaging the surface on impact. If just a kink was
sufficient, every crossed spoke would fail, as would every
"corrected line" spoke that you advocate.

Explain how that would be so. There needn't be any plastic flow or
gouging in a kink to cause failure. My reference to a kink is one
induced by, for instance, a wheel collapse in which a spoke is doubled
back on itself or one in which the wheel fell on an unoccupied pedal
and got snagged by a projecting part in a crash. These are sharp
bends in the middle of a spoke. Ones that cannot be straightened by
anything but a hammer and smooth surface to fatten the kink, and even
then it is doubtful to be durable. In effect an unsupported "elbow".

Quoted message said:

Quoted message said:

Even smooth bends have practically no effect on spoke life.
Replacement spokes must often be bent to insert them into the hub.
The main thing is to stress relieve them after truing. That's what
assures durability for high quality spokes.

Quoted message said:

Interesting qualification - that high quality spokes assure
durability. Can it therefore be inferred that you don't feel
confident that "stress relief" has the same magical properties of
infinite fatigue life on poor quality spokes? If so, what would be
the differentiator?

I see you didn't live in the days of Stella and Robergel spokes from
which I discovered the benefits of stress relieving. These spokes
broke after such short duty that a large statistical trend was
discernable by stress relieving although that did not stop spoke
failures entirely. It was with the advent of DT spokes that truly
durable spokes became available. Now there are several brands that
work well.

As I have described here often, spoke wire must be ductile enough to
withstand cold forming yet retain a sufficiently high yield strength
to resist fatigue failures at normal spoke loadings. This had not
been so before DT spokes so there is where you should look for the
answer. Redaelli, Berg, and Prym spokes also did not survive long
even with stress relieving although it extended their service life.

Quoted message said:

It's interesting how you're so very careful with your claims; when
challenged you fall back on your personal use of just one brand of
top quality spoke, as if it were proof across the whole
mechanical/materials spectrum.

You create these characterizations of thin air to your liking. Every
so often someone with your attitude shows up here on wreck.bike to
attack what has been discovered about bicycle parts apparently trying
to defend myth and lore from days gone by. I can't see any other goal
but then you never said what you believe is the cause of failures.
Instead of beating around the bush and insinuating and alluding to
some agenda, how about stating what it is you believe is occurring.

Jobst Brandt
[email hidden]

RWM said:

You edited the message wrong. It went like this:

Quoted message said:

But how do you "ruin" the rim? Did it become impossible to true
after?

Yes.

OK, this is making less and less sense. I've had to ride home on
broken spokes more than 50 miles on occasion, and over 10 miles on
several occasions- happily not in years. I've never ruined a rim by
riding on it with a broken spoke- and I've weighed over 195 lbs since
I was a sophomore in high school back in 1974. I built my first
wheels in 1978 and finally retired those in 1994. I don't recall any
spoke breakages in those wheels, but I have had spokes break in OEM
prebuilt wheels and in one wheel I built using cheap Asahi spokes;
otherwise I find 32 spoke wheels quite adequate.

When you say the rim was "not truable," by whom was it not truable?

Basically it sounds like your wheels have been built up by people who
didn't know what they were doing- how to properly tension the spokes,
remove spoke windup and stress relieve them to prevent breakage. A
wheel should go 50,000 miles at least without breaking a spoke, IMHO.
This is not hard to achieve once the principles and procedures of good
wheel building are known.

Quoted message said:

Old Crow or was it Wild Turkey said:

Quoted message said:

>Thinking back on it, I supposed that the second spoke popping
>could have been the result of the two spills I had on Saturday,
>but given the fact that the lady apparently (and I see this only
>because I saw lateral movement and she saw radial movement while
>spinning the wheel -- which resulted in her working on it some
>more) did not do a good job truing the wheel, I'm not so certain.

Quoted message said:

Quoted message said:

That should not compromise spoke life although it might damage the
rim so that it cannot be made as true as a new one, or maybe not at
all if it was collapsed, but that should not affect spoke life.
Spoke life is shortened by not stress relieving and from kinks
caused by foreign objects against them to cause kinks.

Quoted message said:

It's not the just kink, it's the stress riser caused by a sharp
object damaging the surface on impact. If just a kink was
sufficient, every crossed spoke would fail, as would every
"corrected line" spoke that you advocate.

Explain how that would be so. There needn't be any plastic flow or
gouging in a kink to cause failure.

by definition, for the material to take any permanent set, there has to
be plastic deformation. whether that be caused by bending or something
sharper like chain gouge or pedal strike is open to circumstance.

Quoted message said:

My reference to a kink is one
induced by, for instance, a wheel collapse in which a spoke is doubled
back on itself or one in which the wheel fell on an unoccupied pedal
and got snagged by a projecting part in a crash. These are sharp
bends in the middle of a spoke. Ones that cannot be straightened by
anything but a hammer and smooth surface to fatten the kink, and even
then it is doubtful to be durable. In effect an unsupported "elbow".

understood, but there are two types of "sharp" bend. the bending that
has a comparatively large radius like a straightened paper clip, or the
minor bend which has a very small radius like a chain gouge. the
smaller the radius, the greater the stress concentration & the greater
fatigue propensity. the large radius bend induces similar effects in
the material to "correcting the line".

Quoted message said:

Quoted message said:

Quoted message said:

Even smooth bends have practically no effect on spoke life.
Replacement spokes must often be bent to insert them into the hub.
The main thing is to stress relieve them after truing. That's what
assures durability for high quality spokes.

Quoted message said:

Interesting qualification - that high quality spokes assure
durability. Can it therefore be inferred that you don't feel
confident that "stress relief" has the same magical properties of
infinite fatigue life on poor quality spokes? If so, what would be
the differentiator?

I see you didn't live in the days of Stella and Robergel spokes from
which I discovered the benefits of stress relieving.

but i'm not too old to still find wheels with these spokes at swap meets.

Quoted message said:

These spokes
broke after such short duty that a large statistical trend was
discernable by stress relieving although that did not stop spoke
failures entirely. It was with the advent of DT spokes that truly
durable spokes became available. Now there are several brands that
work well.

yes, there are now several brands that work well. but their long life
is not the product of "stress relief"; it's the fact that in the 70's,
it became economic to mass produce vacuum degassed steels. ultra-clean
materials like this are substantially more fatigue resistant because
this process virtually eliminates inclusions, thereby removing a
significant source of fatigue initiation.

a traditional steel for example may have half the fatigue limit in the
transverse axis of a rolled sheet compared to its longitudinal axis.
the same alloy composition, but vacuum degassed, may have very similar
fatigue limits in both orientations. when first seen, the observation
of this effect sparked a hunt for explanation. electron microscopy
subsequently confirmed fatigue initiation at tiny inclusions previously
thought to be insignificantly small.

Quoted message said:

As I have described here often, spoke wire must be ductile enough to
withstand cold forming yet retain a sufficiently high yield strength
to resist fatigue failures at normal spoke loadings. This had not
been so before DT spokes so there is where you should look for the
answer. Redaelli, Berg, and Prym spokes also did not survive long
even with stress relieving although it extended their service life.

Quoted message said:

It's interesting how you're so very careful with your claims; when
challenged you fall back on your personal use of just one brand of
top quality spoke, as if it were proof across the whole
mechanical/materials spectrum.

You create these characterizations of thin air to your liking. Every
so often someone with your attitude shows up here on wreck.bike to
attack what has been discovered about bicycle parts apparently trying
to defend myth and lore from days gone by. I can't see any other goal
but then you never said what you believe is the cause of failures.
Instead of beating around the bush and insinuating and alluding to
some agenda, how about stating what it is you believe is occurring.

what causes failures is well known. it's what alleviates them that
seems to be the issue here. all that "stress relief" achieves is a
wheel that is fully bedded in before riding. spokes do not therefore
loosen and others do not therefore carry disproportionate load. in that
respect, the practice referred to as "stress relief" is a good thing,
and thoroughly to be commended. but the business of fatigue mitigation
itself is achieved in the spoke manufacturers factory, not the wheel
builders bench.

the explanation of "local yielding" you've presented as theory on how to
eliminate fatigue is unfortunately built on some gross misconceptions.
you assert that the steel in spokes exhibits the same properties as mild
steel, i.e. the exhibition of yield and deformation without work
hardening as a method of reducing residual stress. reality is,
stainless steel spoke wires /do/ work harden immediately from yield, as
the real-life spoke stress/strain graphs in the back of your book show.
"stress relief" therefore has the ability to not only continue
increasing the dislocation density of the material [which /increases/
lattice stresses] at any point where it does yield, [/if/ it yields, and
that's conjecture], but to also activate slip bands and initiate
cumulative damage effects.

the closest analogy to your explanation is something called "coaxing"
where a component is progressively loaded and fatigue limits improved,
but unfortunately, this effect is only present in materials that exhibit
strain aging. stainless steel is not one of them.

so, you want to know my agenda? update your book and get rid of the
glaring materials theory errors! and please include the differential
spoke tension formula for dished wheels while you're at it.

Quoted message said:

Jobst Brandt
[email hidden]

[email hidden] wrote:
:: Roger Zoul writes:
::
::::: I don't know anything about Rolf but I'm getting a notion that
::::: they are somehow designed for speed.
::
:::: Not really. They are designed to make you think of speed, the
:::: difference being only measurable with a stop watch at maximum
:::: effort. They aren't lighter nor are they pleasant to ride in
:::: winds.
::
::: Why would they not be pleasant to ride in winds? Is there some
::: design feature?.
::
:: If you have not ridden in strong winds you probably cannot imagine
:: how they affect steering. It is like someone putting their hand on
:: the end of your bars and pushing a bit one way or the other. Strong
:: winds, even from behind, are turbulent and have cross components to
:: the direction of travel. Of course direct cross winds are worse.
:: The point is that aero wheels have far larger surfaces for the wind
:: to attack than conventional wheels.

That makes perfect sense....I guess what I really didn't realize is that
there was something different about the wheels on this bike. Once again,
I'm a bicycling noob, here. This is my first bike and I didn't do a lot of
research before buying it, even though I spent a good bit of time riding
various bicycles. The other postered mentioned something about "deep rims"
but I'm still a little confused by that, since they don't seem "deep" to me.

[email hidden] wrote:
:: Roger Zoul <[email hidden]> writes:
::
::: If I need to find a wheel builder, how do you suggest I proceed? I
::: live in Greenville SC. What about Peter White? He offers lifetime
::: if you go with his suggestions. I like to notion of that since
::: obviously he intends to back up what he does.
::
:: Build your own. If you can follow instructions, you can probably
:: build abetter wheel than you can get from most bicycle shops.
::
:: http://www.avocet.com/wheelbook/wheelbook.html
:: http://tinyurl.com/22lrv
::
:: Available at many bicycle shops including ones who can't build a good
:: wheel. They don't need no steenking books. They already know all
:: about the subject... they think.

I had ordered it before seeing your post. I hope the 3rd edition is the
last.

Roger Zoul said:

This is my first bike and I didn't do a lot of
research before buying it, even though I spent a good bit of time riding
various bicycles.

That's the most important part.

Quoted message said:

The other postered mentioned something about "deep rims"
but I'm still a little confused by that, since they don't seem "deep" to me.

Here's a couple examples:
Deep V rim: http://www.poweroncycling.com/images/VELOCITY_DEEP_V.jpg
Semi-aero rim:
http://www.triathletesworld.com.au/img/pics/030_wheel_sm.jpg
Standard rim:
http://www.nashbar.com/profile_moreimages.cfm?&sku=6367

The difference is the cross-sectional shape of the rim. If it's just
flat, parallel to the road, then it's a standard rim; if it's shaped
like an inverted* 'V', then it's "deep".

*: [at least, the portion nearest the road; at the top, it would be
right-side-up]
--
Rick Onanian