What happened to non-boutique inexpensive MO wheels?
damyth
traditional (32 spoke) 700c non-boutique wheels. I go over to the
usual mail order places like Nashbar and Performance, but there are
none to be found! All they have now are boutique wheels and
non-boutique 650c. :(
I always used to get pre-built wheels via MO since those places offered
wheelsets at lower prices than the cost of individual of components.
Is this a fluke (maybe these places ran out traditional wheels since
it's end of the season) or the wave of the future? I really hope it's
not the latter. I remember even 6 months ago Nashbar was selling
Ritchey OCR wheelsets at extremely low prices. I'm kicking myself now
for not having bought some then.
In any case, please recommend decently durable rims for riders less
than 165 lbs. Need the right balance between durability and weight.
Ever since my Mavic rims started cracking at eyelets I've stopped using
them. What a good source for Velocity or Alex clincher rims (and are
Alex any good)?
carl...@comcast.net
<mdk.10...@spamgourmet.com> wrote:
>OK, so I'm in the market for some nice but inexpensive pre-built
>traditional (32 spoke) 700c non-boutique wheels. I go over to the
>usual mail order places like Nashbar and Performance, but there are
>none to be found! All they have now are boutique wheels and
>non-boutique 650c. :(
[snip]
Dear Damyth,
Possibly you need to sort the Performance Bike wheel page from low to
high price? Or adjust your notion of inexpensive for inflation? Or
wait for sales?
Mavic Open Pro CD 32-spoke front $119.99:
http://www.performancebike.com/shop/profile.cfm?SKU=19030&subcategory_ID=5320
Ultegra Open Pro Silver 32-spoke front $119.9:
http://www.performancebike.com/shop/profile.cfm?SKU=19027&subcategory_ID=5320
And so on.
Cheers,
Carl Fogel
Donald Gillies
Weinmann 700x35c front and rear QR 36H freewheel wheels, out the door
for less than $52.00 + s/h, from bikepartsusa. I think it uses a
Sovos hub. Also, I think it's in stock at a major distributor, so
your LBS could get it, but they'd probably charge you > $100/pair for
this same set of wheels ...
- Don Gillies
San Diego, CA
Donald Gillies
perpetual sale at PerfBike for $299.95, are now "only" $374.98.
Perhaps Performance - thinking they have now corned the market for
mail order goods - has decided to tighten the screws on the American
Consumer ??
Michael Press
<1162104193.4...@e3g2000cwe.googlegroups.com>,
"damyth" <mdk.10...@spamgourmet.com> wrote:
> OK, so I'm in the market for some nice but inexpensive pre-built
> traditional (32 spoke) 700c non-boutique wheels. I go over to the
> usual mail order places like Nashbar and Performance, but there are
> none to be found! All they have now are boutique wheels and
> non-boutique 650c. :(
So, now 32 spoke wheels are traditional?
--
Michael Press
damyth
Had you read my original post in its entirety (which you snipped)
perhaps you would have realized I'd avoid Mavic like the plague. In
fact I believe my exact words were: "Ever since my Mavic rims started
cracking at eyelets I've stopped using them." Perhaps I could have
been clearer in my writing style, but explain to me why I should go
back using/buying the same rims that cracked once on me already.
damyth
32 spokes have always been "traditional" at Nashbar and Performance for
at least the last 15 years. Not to mention "for riders less than 165
lbs" (per my original post), 32 spokes are plenty.
John Forrest Tomlinson
Sure -- if built right they're almost bomb-proof except maybe for
loaded touring and people over 200#.
--
JT
****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************
Qui si parla Campagnolo
Gotta excuse Carl, sometimes his whizbang internet connection and
typing skills get in the way.
$350 gets you Ultegra hubs, Velocity Aero rims, DT db spokes and
Vecchio's build-
me
"damyth" <mdk.10...@spamgourmet.com> wrote in message
news:1162114083.2...@e3g2000cwe.googlegroups.com...
You must live and ride where the squirrel menace isn't too serious yet.
The rest of us ride 36 to 40 hole rims just to keep the suicidal rats out of
our forks.
Cal
Tim McNamara
John Forrest Tomlinson <usenet...@jt10000.com> wrote:
> On Sun, 29 Oct 2006 09:15:44 GMT, Michael Press <ja...@abc.net> wrote:
>
> >In article <1162104193.4...@e3g2000cwe.googlegroups.com>,
> > "damyth" <mdk.10...@spamgourmet.com> wrote:
> >
> >> OK, so I'm in the market for some nice but inexpensive pre-built
> >> traditional (32 spoke) 700c non-boutique wheels. I go over to the
> >> usual mail order places like Nashbar and Performance, but there
> >> are none to be found! All they have now are boutique wheels and
> >> non-boutique 650c. :(
> >
> >So, now 32 spoke wheels are traditional?
>
> Sure -- if built right they're almost bomb-proof except maybe for
> loaded touring and people over 200#.
I ride on 32 spoke wheels and weigh (this week) 209#. I've weighed
195-200 during my racing days (I'm ~ 6'4") and around 215 since I quit.
I haven't had any problems with 32 spoke wheels built 3x on MA2 rims
using Shimano 8/9 speed or Campy 9 speed hubs- despite being told
repeatedly that you can't use MA2s with those hubs. The wheels stay
true and seem plenty strong. I haven't tried loaded touring on them
because I don't care for that sort of thing, but these wheels have
worked fine for credit card touring with a saddlebag.
Andrew F Martin
> OK, so I'm in the market for some nice but inexpensive pre-built
> traditional (32 spoke) 700c non-boutique wheels.
Try Excel Sports Boulder (www.excelsports.com). They have a series of
wheels built with Shimano, DT, or even Chris King hubs laced to DT
rims. If I had the means, I'd love to get some of their King
wheelsets.
Matt O'Toole
Pricepoint (www.pricepoint.com) usually has Ultegra/OpenPro/butted for
under $200/pair. I don't know what you'd call budget or boutique.
Matt O.
carl...@comcast.net
<pe...@vecchios.com> wrote:
Dear Damyth and Peter,
Actually, I read it, but when someone is complaining that they can't
get cheap mail order rims, worrying about brand seems a bit much.
Cheers,
Carl Fogel
landotter
damyth wrote:
> What a good source for Velocity or Alex clincher rims (and are
> Alex any good)?
I sourced my last rims at aebike.com. Super speedy service and
seriously low prices. As far as Alex rims go, I've owned a lot of bike
over around 20 years of semi-serious riding and commuting, and Alex
rims are the only brand that's never ever let me down. I've had four
sets of wheels with them. A lot of people kvetch about them, but I'll
venture and guess that their wheels were built poorly, and it wasn't
the fault of the rim. Their basic silver eyeletted box section rim is
the most reliable rim I've ever used. Model number DM18 (I think).
Twenty bucks a pop. Your mileage may vary, offer does not apply on
Sundays.
I'd say build a set for fun, between some decent Alex rims, stainless
spokes, and hubs sourced from Ebay or craigslist, you should be able
throw some super durable wheels together for around a hundred bucks or
so.
Dan
Michael Press
> On Sun, 29 Oct 2006 09:15:44 GMT, Michael Press <ja...@abc.net> wrote:
>
> >In article
> ><1162104193.4...@e3g2000cwe.googlegroups.com>,
> > "damyth" <mdk.10...@spamgourmet.com> wrote:
> >
> >> OK, so I'm in the market for some nice but inexpensive pre-built
> >> traditional (32 spoke) 700c non-boutique wheels. I go over to the
> >> usual mail order places like Nashbar and Performance, but there are
> >> none to be found! All they have now are boutique wheels and
> >> non-boutique 650c. :(
> >
> >So, now 32 spoke wheels are traditional?
>
> Sure -- if built right they're almost bomb-proof except maybe for
> loaded touring and people over 200#.
What is done _now_ is not evidence that such is traditional.
--
Michael Press
John Forrest Tomlinson
>In article
><0029k2d9tn6llg06j...@4ax.com>,
> John Forrest Tomlinson <usenet...@jt10000.com>
> wrote:
>
>> On Sun, 29 Oct 2006 09:15:44 GMT, Michael Press <ja...@abc.net> wrote:
>>
>> >In article
>> ><1162104193.4...@e3g2000cwe.googlegroups.com>,
>> > "damyth" <mdk.10...@spamgourmet.com> wrote:
>> >
>> >> OK, so I'm in the market for some nice but inexpensive pre-built
>> >> traditional (32 spoke) 700c non-boutique wheels. I go over to the
>> >> usual mail order places like Nashbar and Performance, but there are
>> >> none to be found! All they have now are boutique wheels and
>> >> non-boutique 650c. :(
>> >
>> >So, now 32 spoke wheels are traditional?
>>
>> Sure -- if built right they're almost bomb-proof except maybe for
>> loaded touring and people over 200#.
>
>What is done _now_ is not evidence that such is traditional.
How long does it take for something to become traditional?
Is the key requirement that it be in widespread use when you got into
the sport?
Qui si parla Campagnolo
spokes and rims are consumables..hubs should be reused. With a $50
wheel, don't expect a decent hub.
russell...@yahoo.com
> damyth wrote:
> > What a good source for Velocity or Alex clincher rims (and are
> > Alex any good)?
>
> I sourced my last rims at aebike.com. Super speedy service and
> seriously low prices. As far as Alex rims go, I've owned a lot of bike
> over around 20 years of semi-serious riding and commuting, and Alex
> rims are the only brand that's never ever let me down. I've had four
> sets of wheels with them. A lot of people kvetch about them, but I'll
> venture and guess that their wheels were built poorly, and it wasn't
> the fault of the rim. Their basic silver eyeletted box section rim is
> the most reliable rim I've ever used. Model number DM18 (I think).
> Twenty bucks a pop. Your mileage may vary, offer does not apply on
> Sundays.
I've been riding a bit the past 25 years and I'd never heard of the
name "Alex" in the bike industry before about 1 year ago. I'm more
than a bit surprised to hear they have been around for two decades. I
was a bit miffed to see Performance is up to $275 on Record/Mavic
wheels. They must be getting a jump on Ben.
Johnny Sunset aka Tom Sherman
Qui si parla Campagnolo aka Peter Chisholm wrote:
>
> spokes and rims are consumables..hubs should be reused....
Jobst Brandt writes <http://yarchive.net/bike/spoke_reuse.html>.
--
Tom Sherman - Here, not there.
landotter
russell...@yahoo.com wrote:
> landotter wrote:
> > damyth wrote:
> > > What a good source for Velocity or Alex clincher rims (and are
> > > Alex any good)?
> >
> > I sourced my last rims at aebike.com. Super speedy service and
> > seriously low prices. As far as Alex rims go, I've owned a lot of bike
> > over around 20 years of semi-serious riding and commuting, and Alex
> > rims are the only brand that's never ever let me down. I've had four
> > sets of wheels with them. A lot of people kvetch about them, but I'll
> > venture and guess that their wheels were built poorly, and it wasn't
> > the fault of the rim. Their basic silver eyeletted box section rim is
> > the most reliable rim I've ever used. Model number DM18 (I think).
> > Twenty bucks a pop. Your mileage may vary, offer does not apply on
> > Sundays.
>
> I've been riding a bit the past 25 years and I'd never heard of the
> name "Alex" in the bike industry before about 1 year ago. I'm more
> than a bit surprised to hear they have been around for two decades.
I've been riding them on road and utility bikes for a decade now.
Perfectly decent stuff. They make rims at all price points. You'd have
heard of them earlier had you been into BMX. They came as OEM for many
years before they caught on in catalogs. I'll take Alex over Mavic any
day of the week. Can't be beat for value. Sun and Velocity are nice as
well, but nothing wrong with a properly laced Alex.
landotter
Take a Sora or 2200 low end hub. $10-15 or so. Repack and adjust with
good grease and $1 worth of 25 grade bearings and you'll have a hub
that will last a long time and spin smooth. Won't be good looking, but
in a pinch does the trick. Soras or 2200s will pit and score in just a
few miles out of the box, but the functional quality is due mainly to
adjustment and the bearing quality. Again, they're not pleasant on the
eyes, but for a tenner, whaddaya expect?
For inexpensive track hubs, I've been blown away by the quality of the
Formulas on my new fixie.
Qui si parla Campagnolo
If the ERD is the same.
Ozark Bicycle
> get cheap mail order rims, worrying about brand seems a bit much.
>
Not if the OP is turned off to the Mavic brand due to premature rim
failures. Why would anyone want to spend over $200 for a pair of wheels
built with rims they think are failure prone?
SYJ
Michael Press wrote:
>
> What is done _now_ is not evidence that such is traditional.
>
> --
> Michael Press
You're right. When I refer to 'traditional' wheels, I'm generally
talking about something made of stone with a wooden axel ;-)
SYJ
Johnny Sunset aka Tom Sherman
Qui si parla Campagnolo aka Peter Chisholm wrote:
> Johnny Sunset aka Tom Sherman wrote:
> > Qui si parla Campagnolo aka Peter Chisholm wrote:
> > >
> > > spokes and rims are consumables..hubs should be reused....
> >
> > Jobst Brandt writes <http://yarchive.net/bike/spoke_reuse.html>.
> >
> > --
> > Tom Sherman - Here, not there.
>
> If the ERD is the same.
True.
How common are non-bearing hub failures, and of those, are most from
radial spoking the wheel?
David L. Johnson
> How common are non-bearing hub failures, and of those, are most from
> radial spoking the wheel?
>
Not, is the first answer. But, if most hub failures are bearing failures,
and the cups are not replaceable, then it does not matter. I have seen
pictures of hub flanges tearing out, but it's not obvious that these
failures are due to radial spoking. I used a front hub for several years
that had the spoke holes sliced to admit bladed spokes, which was not
Shimano's original intent, and the hub worked fine. I personally do not
believe that radial spoking is that horrible a thing to do, although the
name brands void their warrantee for it. For front wheels there is no
harm, and no advantage aside from coolness, to use radial spoking. For
the rear, right side, it is not a good idea although lots of boutique
wheels use it -- if they do, they have to beef up the hub shell, which
adds weight needlessly. Using radial spoking on the left side seems to be
a slight advantage, in that it helps deal with the extreme dish of modern
wheels.
--
David L. Johnson
__o | Do not worry about your difficulties in mathematics, I can
_`\(,_ | assure you that mine are all greater. -- A. Einstein
(_)/ (_) |
jim beam
>> spokes and rims are consumables..hubs should be reused....
>
> Jobst Brandt writes <http://yarchive.net/bike/spoke_reuse.html>.
>
choice quotes from that linkage:
* [they] "do not fatigue age with use"
* "they have residual locked in high stresses"
but here's the real peach:
"Once a set of spokes has been stress relieved and is working well, you
do yourself a great disservice by throwing them away when rebuilding
with a new rim because you must go through the weeding out of spokes
that will break due to peculiarities that leave them with residual
stress."
translation:
"so, having discarded the spokes that previous broke, we can now set up
to make claims about having eliminated fatigue".
since we have yet to be privileged with sight of the jobstian research
that will revolutionize the world of materials by showing how fatigue
can be eliminated in a material with no endurance limit and, we're
somewhat thin on evidence for this supposition that spokes are sent from
the factory containing residual stress [jobst has declined to provide
the results of his x-ray, neutron diffraction or even stress-corrosion
testing], i'd say it's time to stop propagating bad advice about
re-using spokes. sure, you can re-use at a pinch, but as a matter of
economics and engineering principle, it's an exercise in pointlessness.
jo...@phred.org
spamv...@bad.example.net says...
> since we have yet to be privileged with sight of the jobstian research
> that will revolutionize the world of materials by showing how fatigue
> can be eliminated in a material with no endurance limit
I thought most spokes were 304 stainless steel?
--
jo...@phred.org is Joshua Putnam
<http://www.phred.org/~josh/>
Braze your own bicycle frames. See
<http://www.phred.org/~josh/build/build.html>
jim beam
> In article <LpKdnU-2-7wfL9vY...@speakeasy.net>,
> spamv...@bad.example.net says...
>
>> since we have yet to be privileged with sight of the jobstian research
>> that will revolutionize the world of materials by showing how fatigue
>> can be eliminated in a material with no endurance limit
>
> I thought most spokes were 304 stainless steel?
>
limit. they have what's called a "fatigue limit" which is an attempt to
quantify the stress they can endure for a given number of fatigue
cycles, but that's not the same thing. an endurance limit is the stress
at which the material can endure an infinite number of cycles, and is
characterized by a "knee" in the s-n graph where the line goes
horizontal. mild steel is the classic material with this property, but
some titanium alloys also have it. no stainless alloys that i know of
have it.
Ted P.
over the head and makin' wheels outa big rocks with nothin' but a wooden
axe(l).
--
Ted
Don't forget to take out the trash
Peter Cole
<users.wpi.edu/~cfurlong/me3320/lect13/Lect13.pdf>
<bama.ua.edu/~mweaver/courses/MTE455/MTE455_2006_L26.pdf>
That's not what they're teaching today.
Rick
damyth wrote:
> OK, so I'm in the market for some nice but inexpensive pre-built
> traditional (32 spoke) 700c non-boutique wheels. I go over to the
> usual mail order places like Nashbar and Performance, but there are
> none to be found! All they have now are boutique wheels and
> non-boutique 650c. :(
>
> wheelsets at lower prices than the cost of individual of components.
> Is this a fluke (maybe these places ran out traditional wheels since
> it's end of the season) or the wave of the future? I really hope it's
> not the latter. I remember even 6 months ago Nashbar was selling
> Ritchey OCR wheelsets at extremely low prices. I'm kicking myself now
> for not having bought some then.
>
> In any case, please recommend decently durable rims for riders less
> than 165 lbs. Need the right balance between durability and weight.
> Alex any good)?
Nasbar is Performance's surplus house; they sell what they get cheap as
surplus. Those Ritchey OCR wheels you saw meant some supplier or
vendor had an overstock Performance could pick up on the cheap and sell
at low prices. Not a reliable way to find parts.
As for Mavic rims, I too have had issues with MA3's and will not use
them. But the Open Pro and T520/A719 are rock solid components and I
would not hestitate to use either; in fact I will probably be looking
from some A719's soon as my wife has 14K miles on the wheels on her
commuter which are based on T520 (same rim, different name/number).
Why not just get a good set of wheels on a rock solid hub you can use
for years?
- rick
jim beam
how so?
regarding endurance limit, both seem to corroborate the same definition
as i, although the second uses fatigue limit and endurance limit
interchangeably between diagrams and text.
regarding which alloys evidence an endurance limit, the first one says
some types of stainless can show it, but i saw no examples. or if they
did, and/or you know any, please share. i'm interested because fwiu,
endurance limits originate with the same mechanism that causes strain
aging, i.e. interstitial elements [carbon in mild steel and oxygen in
titanium] locking dislocations. the thing with chromium passivated
stainless is that there's very little carbon possible without having
chromium carbide precipitate at grain boundaries, a big no-no for
fatigue, among other things. there are other types of "stainless", but
they're not something you or i would buy off the shelf and i've not
heard of their use for fatigue resistance. i definitely don't see them
being used in bicycle spokes.
Peter Cole
As you say, the first notes claim some stainless steels have a flat S/N
curve, some don't. The second reference claims that all stainless are
flat (pg, 4) "Ferrous metals and other strain aging materials --
Examples: low carbon steel, stainless steel, titanium, etc."
Another source is:
<http://www.kuleuven.ac.be/bwk/materials/Teaching/master/wg12/l0200.htm#SEC_6_1>
Sec. 5.1
"The S-N curves for ferrous and titanium alloys exhibit a limiting
stress below which failure does not occur; this is called the fatigue or
the endurance limit. The branch point or "knee" of the curve lies
normally in the 105 to 107 cycle range. In aluminium and other
nonferrous alloys there is no stress asymptote and a finite fatigue life
exists at any stress level. All materials, however, exhibit a relatively
flat curve in the high-cycle region, ie. at lives longer than about 105
cycles."
jta...@nospam.hfx.andara.com
This is "jim beam" you're arguing with - he's the guy that thinks that
you tighten a cotter pin with the nut. You'd best give up; if you
don't, eventually he'll suggest trial by combat is the best way to
decide the truth.
Peter Cole
<http://www.kuleuven.ac.be/bwk/materials/Teaching/master/wg12/l0200.htm#SEC_6_1>
Sec. 6.6
"Residual stresses or internal stresses are produced when a region of a
part is strained beyond the elastic limit while other regions are
elastically deformed. When the force or deformation causing the
deformation are removed, the elastically deformed material springs back
and impose residual stresses in the plastically deformed material.
Yielding can be caused by thermal expansion as well as by external
force. The residual stresses are of the opposite sign to the initially
applied stress. Therefore, if a notched member is loaded in tension
until yielding occurs, the notch root will experience a compressive
stress after unloading. Welding stresses which are locked in when the
weld metal contracts during cooling are an example of highly damaging
stresses that cannot be avoided during fabrication. These stresses are
of yield stress magnitude and tensile and compressive stresses must
always balance each other, as indicated in Figure 26. The high tensile
welding stresses contribute to a large extent to the poor fatigue
performance of welded joints."
"Residual stresses have a similar influence on fatigue life as
externally imposed mean stresses, ie. a tensile stress reduces fatigue
life while a compressive stress increases life. There is, however, an
important difference which relates to the stability of residual
stresses. While an externally imposed mean stress, eg. stress caused by
dead weight always acts (as long as the load is present), residual
stress may relax with time, especially if there are high peaks in the
load spectrum that cause local yielding at stress concentrations."
dvt
That's a great link, Peter! Thanks.
Just before the section you quoted, the author of that page writes:
> 6.5 Effects of Surface Finish
> Almost all fatigue cracks nucleate at the surface since slip occurs
> easier here than in the interior. Additionally, simple fracture
> mechanics considerations show that surface defects and notches are
> much more damaging than internal defects of similar size. The
> physical condition and stress situation at the surface is therefore
> of prime importance for the fatigue performance.
Combining these factors, any surface defect near a region with residual
tensile stress would be a very weak point. A spoke elbow certainly has
residual stress, and Jobstian theory (in agreement with section 6.6 of
the link) says that the residual tensile stresses can be ameliorated by
overload. Combining this with improved spoke processing to reduce
surface defects (jim beamian theory, section 6.5 of the link), would
result in a great reduction of broken spokes.
Summary: perhaps both effects (residual stress and surface defects) play
interactive roles in reducing spoke life. Treating either of these may
be sufficient to all but eliminate broken spokes.
Comments?
--
Dave
dvt at psu dot edu
Peter Cole
after taking a small chain nick. Jobst has remarked about the
improvement in quality of modern spokes, speculating that if old spokes
had been better he might not have discovered the benefits of stress
relieving. Modern spokes may have reduced un-relieved breakage rates,
but not eliminated them.
carl...@comcast.net
<peter...@comcast.net> wrote:
>Sure, surface finish is important -- even high quality spokes often fail
>after taking a small chain nick. Jobst has remarked about the
>improvement in quality of modern spokes, speculating that if old spokes
>had been better he might not have discovered the benefits of stress
>relieving. Modern spokes may have reduced un-relieved breakage rates,
>but not eliminated them.
Dear Peter,
I'm fiddling with a simple vise setup for bending and stretching
spokes to see if any stress relief effects can be demonstrated by
heating the bends afterward:
Here's spoke run through holes drilled in the two right-hand bolts and
curving around the bolt on the left:
http://server5.theimagehosting.com/image.php?img=339a_spoke_rig.jpg
or http://tinyurl.com/y9kmws
Here's the spoke tightened to 165 kgf by tension gauge. The elbow
bends straight and disappears into one bolt, while the nipple cocks
sideways on the point of the other bolt:
http://server5.theimagehosting.com/image.php?img=340a_spoke_rig_165kgf.jpg
or http://tinyurl.com/ycnr2f
Here's the spoke with the elbow end cut off to allow removal (the
u-bend won't fit through the holes drilled in the bolt heads) and
showing the resulting bend:
http://server5.theimagehosting.com/image.php?img=341a_spoke_rig_elbow_cut.jpg
or http://tinyurl.com/yenfz9
I plan to bend a dozen stainless steel spokes up to the same tension,
measure the change in bend angle when they're heated to relieve
residual tensions, and then compare them to a dozen more spokes
treated the same way--but squeezed with a known force reasonably
similar to what a hand squeeze can do.
Right now, I'm working on the squeeze part, since pliers squeeze so
easily and powerfully that impressive bends are left in the spokes:
http://server5.theimagehosting.com/image.php?img=342a_spoke_squeeze_bends.jpg
or http://tinyurl.com/tdkf3
I've been sacrificing old carbon steel spokes, which bend the opposite
way from stainless steel spokes when heated, probably because the
carbon undergoes phase changes that overwhelm residual stress changes.
Anyway, here are some Sapim Leader straight 14 gauge spokes that just
arrived:
http://server5.theimagehosting.com/image.php?img=338a_sap.jpg
or http://tinyurl.com/ya3lzr
Notice the S-A-P stamped into them, a little below the elbow.
Obviously, Sapim doesn't think that these sharp-edged little dents
will lead to spoke failures. As far as I know, the spokes never break
down there.
I wonder if Sapim gets away with banging SAP into the spokes because
the stamping is not near the elbow or the threads, or because the
stamping stresses are mostly compressive.
Cheers,
Carl Fogel
carl...@comcast.net
D'oh! Forget the pliers.
I should just tighten a dozen spokes to say 100 kgf.
Then do the same to another dozen spokes, but tighten them another 30
kgf to mimic previously measured spoke tension increases when spokes
were squeezed with 60 lb squeeze forces--same effect as squeezing,
with no extra bending.
CF
jim beam
i'm not saying that. i've not seen a stainless steel that evidences an
endurance limit, as defined by a "knee" in the graph. some stainless
steels appear to flatten, but there is no knee, hence no endurance limit.
> The second reference claims that all stainless are
> flat (pg, 4) "Ferrous metals and other strain aging materials --
> Examples: low carbon steel, stainless steel, titanium, etc."
cite the alloys and explain the mechanism. endurance limit is cause by
the mechanism i explained, carbon in ferrous metals, and is problematic
in chromium passivated stainless, again for the reasons i explained.
>
> Another source is:
> <http://www.kuleuven.ac.be/bwk/materials/Teaching/master/wg12/l0200.htm#SEC_6_1>
>
>
> Sec. 5.1
>
> "The S-N curves for ferrous and titanium alloys exhibit a limiting
> stress below which failure does not occur; this is called the fatigue or
> the endurance limit. The branch point or "knee" of the curve lies
> normally in the 105 to 107 cycle range. In aluminium and other
> nonferrous alloys there is no stress asymptote and a finite fatigue life
> exists at any stress level. All materials, however, exhibit a relatively
> flat curve in the high-cycle region, ie. at lives longer than about 105
> cycles."
which supports what i said before.
jim beam
dude, with respect, residual stress has NOTHING to do with endurance
limits!!!
jo...@phred.org
> Peter Cole wrote:
> Just before the section you quoted, the author of that page writes:
>
> > 6.5 Effects of Surface Finish
> > Almost all fatigue cracks nucleate at the surface since slip occurs
> > easier here than in the interior. Additionally, simple fracture
> > mechanics considerations show that surface defects and notches are
> > much more damaging than internal defects of similar size. The
> > physical condition and stress situation at the surface is therefore
> > of prime importance for the fatigue performance.
That fits with an insurance industry article I read earlier this year on
fatigue failures of stainless machine components in harsh environments.
While stainless is corrosion-resistant, it's not corrosion-proof, and
some manufacturers apparently fail to de-rate the fatigue limit of
stainless componenets and fasteners used in corrosive environments.
Can't remember the other details precisely, though I seem to recall they
suggested de-rating the fatigue limit of stainless in corrosive
environments to 1/3 of the nominal fatigue limit because of the surface
imperfections introduced by corrosion.
jim beam
do we have evidence for that? a stress corrosion test is simple to do.
none of my test spokes have broken. have any of yours?
> and Jobstian theory (in agreement with section 6.6 of
> the link) says that the residual tensile stresses can be ameliorated by
> overload. Combining this with improved spoke processing to reduce
> surface defects (jim beamian theory, section 6.5 of the link), would
> result in a great reduction of broken spokes.
since /all/ fatigue initiates at free surfaces, regardless of residual
stress, the most important production consideration is surface finish
quality and other factors that can give rise to surface initiation.
residual stress is all well and good to worry about if other factors
have been eliminated, but they haven't. factors not least of which
being the fundamental design of a traditional spoke that requires it to
be loaded in bending mode at the critical elbow!!!
>
> Summary: perhaps both effects (residual stress and surface defects) play
> interactive roles in reducing spoke life. Treating either of these may
> be sufficient to all but eliminate broken spokes.
>
> Comments?
>
sure, if residual stress is sufficient to be a factor, it can help to
reduce it. but the necessary supposition that spoke manufacturers are
incompetent in order to take that position is something of a stretch.
since these supposed incompetents, the ones with the research budgets
and microscopes, spend their time worrying about surface finish and
material quality, /i/ don't think i'm going to back the supposition of a
guy that can't distinguish between materials that strain age and those
that don't or thinks that head set bearings can't true brinell.
Paul Hobson
> For inexpensive track hubs, I've been blown away by the quality of the
> Formulas on my new fixie.
>
Same here! (though one of the two pairs is branded /IRO/)
\\paul
dvt
> dvt wrote:
>> Combining these factors, any surface defect near a region with
>> residual tensile stress would be a very weak point. A spoke elbow
>> certainly has residual stress,
>
> do we have evidence for that?
You guys went round and round on that one in an earlier thread (others
can look to
<http://groups.google.com/group/rec.bicycles.tech/browse_frm/thread/e4d1cf4c90ae456b>
for the gory details). I don't have anything to add to that discussion,
but I don't think you came out on top.
How would you design a test for residual stress in spoke elbows? I have
access to some equipment, but not "neutron/x-ray inferometry" [sic] that
you mentioned in the above-mentioned thread.
> a stress corrosion test is simple to do.
> none of my test spokes have broken.
Can you share details of your test? I don't know how this is relevant.
> have any of yours?
I don't think I've suggested that I've done any such test, nor have I
implied that I would know how to do such a test.
I have broken a few spokes in the past few years. All have failed at the
beginning of the threads, not at the elbow. This is anecdotal, not a
"test." I haven't kept any records of my spokes. I might have one of
those broken spokes around, if that helps.
> sure, if residual stress is sufficient to be a factor, it can help to
> reduce it. but the necessary supposition that spoke manufacturers are
> incompetent in order to take that position is something of a stretch.
I don't think it takes a supposition of incompetence. I'd wager that
spoke manufacturers use the cheapest possible method to get surface
finish good enough that 99+% of the spokes will survive their intended
use. But that leaves a few spokes with surface defects right at (or even
outside) the limit. Perhaps the life of these 3-sigma spokes could be
enhanced via reduction in residual stress.
--
Dave
dvt at psu dot edu
Everyone confesses that exertion which brings out all the powers of body
and mind is the best thing for us; but most people do all they can to
get rid of it, and as a general rule nobody does much more than
circumstances drive them to do. -Harriet Beecher Stowe, abolitionist and
novelist (1811-1896)
Qui si parla Campagnolo
Non bearing, flange destruction, a few. last one was a radial White
Industries hub. I would say not common, not unheard of tho. Depends on
the hub. If it is a high end one, like shimano, Campagnolo, Phil DT,
they will last a long time, can be rebuilt many time. I recently
rebuilt 25 yr old Phils into wheels and a Campag Tipo into wheels...I
ride a 1985 C-Record wheelset every dry day(Phils on my fixie).
Propriatary stuff spells the doom of many wheels. Protons, Heliums,
7700, Rolfs, the l;ist will get longer as time goes on. IF riders will
listen, most will opt for a handbuiult wheelset, regardless of who
builkds them, built well, of course. Less money, same weight, more
reliability but as we all know, marketing, bling, coffee shop points,
mean a whole lot. Peer pressure doesn't go away after HS.
monkeyboy
damyth wrote:
> OK, so I'm in the market for some nice but inexpensive pre-built
> traditional (32 spoke) 700c non-boutique wheels. I go over to the
> usual mail order places like Nashbar and Performance, but there are
> none to be found! All they have now are boutique wheels and
> non-boutique 650c. :(
take a look at cbike.com, they have campy scrirroco wheels for $299,
great wheels at a great price...I guess they could be considered
boutique...?
Peter Cole
I cited 3 sources, 2 of which said all stainless steels have an
endurance limit, the other said some did, some didn't.
From:
<www.stainless-steel-world.net/pdf/11021.pdf>
Page 30 shows an S/N graph for 2 types of stainless, one of which is
common 316. There is clearly a fatigue limit for both alloys.
Peter Cole
No, it doesn't, but you were the one who put them together upthread:
"Since we have yet to be privileged with sight of the jobstian research
that will revolutionize the world of materials by showing how fatigue
can be eliminated in a material with no endurance limit and, we're
somewhat thin on evidence for this supposition that spokes are sent from
the factory containing residual stress"
My cite above was intended as a rebuttal to your (frequent) denial that
mechanical stress relieving doesn't reduce residual stress.
Peter Cole
> In article <eialpk$vvm$1...@f04n12.cac.psu.edu>, dvt+u...@psu.edu says...
>> Peter Cole wrote:
>
>> Just before the section you quoted, the author of that page writes:
>>
>>> 6.5 Effects of Surface Finish
>>> Almost all fatigue cracks nucleate at the surface since slip occurs
>>> easier here than in the interior. Additionally, simple fracture
>>> mechanics considerations show that surface defects and notches are
>>> much more damaging than internal defects of similar size. The
>>> physical condition and stress situation at the surface is therefore
>>> of prime importance for the fatigue performance.
>
> That fits with an insurance industry article I read earlier this year on
> fatigue failures of stainless machine components in harsh environments.
>
> While stainless is corrosion-resistant, it's not corrosion-proof, and
> some manufacturers apparently fail to de-rate the fatigue limit of
> stainless componenets and fasteners used in corrosive environments.
> Can't remember the other details precisely, though I seem to recall they
> suggested de-rating the fatigue limit of stainless in corrosive
> environments to 1/3 of the nominal fatigue limit because of the surface
> imperfections introduced by corrosion.
>
>
This is pretty common knowledge in marine environments.
A more surprising fact is the loss of fatigue strength in many steels
upon exposure to even pure water. The often cited "infinite fatigue
life" may disappear completely. People forget that the S/N behavior
usually referenced is for small, highly polished samples.
Donald Gillies
>>
>> How common are non-bearing hub failures, and of those, are most from
>> radial spoking the wheel?
>>
>Non bearing, flange destruction, a few. last one was a radial White
>Industries hub.
Just goes to show that CNC'ing a hub (as White Industries does) is no
substitute for real cold-forging. Forged hubs are much less likely to
have a failure in the flanges. I have a garage full of bikes, with no
hub newer than 1980, and most of them are wide-flange forged hubs,
which may actually be stronger since the 36 spoke holes are much
farther apart.
- Don Gillies
San Diego, CA
bill
Michael Press wrote:
> In article
> <0029k2d9tn6llg06j...@4ax.com>,
> John Forrest Tomlinson <usenet...@jt10000.com>
> wrote:
>
> > On Sun, 29 Oct 2006 09:15:44 GMT, Michael Press <ja...@abc.net> wrote:
> >
> > >In article
> > ><1162104193.4...@e3g2000cwe.googlegroups.com>,
> > > "damyth" <mdk.10...@spamgourmet.com> wrote:
> > >
> > >> OK, so I'm in the market for some nice but inexpensive pre-built
> > >> traditional (32 spoke) 700c non-boutique wheels. I go over to the
> > >> usual mail order places like Nashbar and Performance, but there are
> > >> none to be found! All they have now are boutique wheels and
> > >> non-boutique 650c. :(
> > >
> >
Yes, 32x is traditional light racing. Has been for like decades. Was
normal for light racing when I started in the 70s. 36x standard, 32x
light, 28x specialty/ front/pursuit, 40 touring, 48 tandem. All
traditional.
He's talking traditional, not standard. Many different configurations
and spoke arrangements are traditional. Hi, low, 2,3,4, straight cross.
All methods have been used traditionally.
Compared to 17 spoke superwhizbang reverse cross pushrod cantilever
sidewinder ergopower wheels, 32x is traditional. Absolutely. Built with
the same parts and methods as wheels built in the 1920s. Just new
aluminum instead of wood. Number of spokes per se has nothing to do
with traditional.
OK enough ranting :-)
jim beam
with respect, one of those two uses "endurance limit" and "fatigue
limit" interchangeably. where i come from, the words "endurance limit"
are reserved for graphs showing the knee, "fatigue limit" is for those
that don't. engineers don't seem to regard materials definitions as
important as materials people, hence the dearth of engineering papers
perpetuating the confusion.
>
> From:
> <www.stainless-steel-world.net/pdf/11021.pdf>
>
> Page 30 shows an S/N graph for 2 types of stainless, one of which is
> common 316. There is clearly a fatigue limit for both alloys.
ok, that's a good link, citing specific alloys. i have two comments:
1. endurance limit at 20-25% of yield is not really a reliable benefit.
2. fatigue is statistical. i'm not saying the publishers of this paper
don't know what they're doing, but be honest peter, there are not a lot
of other materials out there supporting this position - most to the
contrary in fact. therefore, in this portion of the graph, whether you
want to fit one curve or another is open to debate. the determinant,
imo, is whether a mechanism for endurance limit can be identified. in
mild steel, it's carbon diffusion. in titanium, it's oxygen. what is
it here? nitrogen?
jim beam
context: i was contrasting the credibility of someone that claims they
can eliminate fatigue in a situation where they can't, with the fact
that they're making unsupported suppositions.
i've never said you cannot mechanically relieve residual stress. i
/have/ however questioned whether spokes leave the factory with
sufficient residual stress to initiate fatigue /and/ i've questioned the
efficacy of "stress relief" applied after spoke manufacture. mechanical
stress relief is typically only effective a short time after initial
deformation. waiting more than a few hours [as will be necessary to
ship from the spoke manufacturer to the wheel builder] will render this
method useless. and then we can get into the debate of spoke squeezing
itself and whether a process that produces no detectable deformation is
actually yielding the material sufficiently to work as is being
supposed, [timing issues aside of course].
jim beam
> jim beam wrote:
>> dvt wrote:
>>> Combining these factors, any surface defect near a region with
>>> residual tensile stress would be a very weak point. A spoke elbow
>>> certainly has residual stress,
>>
>> do we have evidence for that?
>
> You guys went round and round on that one in an earlier thread (others
> can look to
> <http://groups.google.com/group/rec.bicycles.tech/browse_frm/thread/e4d1cf4c90ae456b>
> for the gory details). I don't have anything to add to that discussion,
> but I don't think you came out on top.
>
> How would you design a test for residual stress in spoke elbows? I have
> access to some equipment, but not "neutron/x-ray inferometry" [sic] that
> you mentioned in the above-mentioned thread.
chlorides are well known for their stress corrosion in stainless steel.
google will help you identify other agents as well. simply leave a
spoke in a jar of the requisite solution and wait.
>
>> a stress corrosion test is simple to do. none of my test spokes have
>> broken.
>
> Can you share details of your test? I don't know how this is relevant.
see above.
>
>> have any of yours?
>
> I don't think I've suggested that I've done any such test, nor have I
> implied that I would know how to do such a test.
>
> I have broken a few spokes in the past few years. All have failed at the
> beginning of the threads, not at the elbow. This is anecdotal, not a
> "test." I haven't kept any records of my spokes. I might have one of
> those broken spokes around, if that helps.
since spoke elbows are the commonest failure point, let's focus on
those. fatigue at threads is common enough in other fastener applications.
>
>> sure, if residual stress is sufficient to be a factor, it can help to
>> reduce it. but the necessary supposition that spoke manufacturers are
>> incompetent in order to take that position is something of a stretch.
>
> I don't think it takes a supposition of incompetence.
i disagree. according to jobstian theory, the supposition is that
spokes leave the factory with residual stress, ergo the manufacturer is
incompetent for not relieving it.
> I'd wager that
> spoke manufacturers use the cheapest possible method to get surface
> finish good enough that 99+% of the spokes will survive their intended
> use.
indeed.
> But that leaves a few spokes with surface defects right at (or even
> outside) the limit. Perhaps the life of these 3-sigma spokes could be
> enhanced via reduction in residual stress.
>
perhaps, but we'd then have to show that residual stress was a factor
and that material quality was not. seriously, if spoke squeezing was
able to eliminate fatigue regardless, don't you think manufacturers
would just do that and use cheaper materials and cheaper processing
rather than what they do now?
jim beam
thank you.
Michael Press
<1162503390.5...@i42g2000cwa.googlegroups.com>
,
"bill" <bi...@plattdesign.net> wrote:
S'allright. My question was at least 50% serious. I am
not stuck on tradition. I bought a frame with a
thread-less steering tube, but built 36 spoke wheels.
The answer is a qualified yes. Thanks.
--
Michael Press
Peter Cole
From:
<http://www.azom.com/details.asp?ArticleID=863>
Tensile strength of 316 is given as 515MPa = 75ksi.
From S/N referenced above, the asymptote is about 33ksi.
Ratio is 44%, typical for steel.
> 2. fatigue is statistical. i'm not saying the publishers of this paper
> don't know what they're doing, but be honest peter, there are not a lot
> of other materials out there supporting this position - most to the
> contrary in fact.
Cite 'em.
Peter Cole
These claims (time dependency & lack of overall plastic yield) seem to
be not supported by the link above and others I have provided. I will
wait for you to provide any evidence to support your claims.
Qui si parla Campagnolo
Except a handbuilt, using Veloce hubs(the base hubs for above mentioned
wheels), Velocity rims and 32 or 36 spokes would cost about the same $
but could be 'designed' for any rider.
jim beam
dieter, mechanical metallurgy, isbn 0-07-016893-8, chapter 19.6,
residual stresses in rod, wire & tubes. [forgive me if i don't dig out
my old lecture notes - one of my old profs was mr. cold drawn steel.]
typical mechanical relief strain is 1%-2%. for a 294mm spoke, where
does that leave us? arguing as jobst does that the relief strain is at
levels microscopic and can't be detected is suppositional straw clutching.
jim beam
there's no asymptote referenced in the azom link. the one showing ~35%
from the stainless-steel-world link is for DP3, whatever that is. and
fyi, ~35% is indistinguishable from the fatigue limit for a lot of
structural aluminum alloys, so i don't think you'll find many people
relying on an endurance limit for DP3 in their fatigue design.
>
>
>
>> 2. fatigue is statistical. i'm not saying the publishers of this
>> paper don't know what they're doing, but be honest peter, there are
>> not a lot of other materials out there supporting this position - most
>> to the contrary in fact.
>
>
> Cite 'em.
dude, google 'stainless steel endurance limit'. there are 170,000
returns, and while i haven't read all of them, the first 50 or so don't
reference an asymptote - or at least, not without also confusing fatigue
and endurance limits. it's been years since you and i first started
this kind of debate, and so far you've cited just one link with a
graphical asymptote. everything else shows a more typical flattening
curve, no asymptote. done any curve fitting exercises lately?
dvt
> Peter Cole wrote:
>> jim beam wrote:
>>> where i come from, the words "endurance
>>> limit" are reserved for graphs showing the knee, "fatigue limit" is
>>> for those that don't.
Amen to that. Google for "define:endurance limit" and you'll find that
most definitions say endurance = fatigue. Ugh.
I do think you "knee" and "asymptote" terms are not quite correct,
though. You use asymptote as a synonym for horizontal. Most S/N curves
that I've seen have a knee (a change in slope). They have two
asymptotes; one above the knee, one below. But materials showing an
endurance limit have a *horizontal* asymptote above the knee.
>>> 2. fatigue is statistical. i'm not saying the publishers of this
>>> paper don't know what they're doing, but be honest peter, there are
>>> not a lot of other materials out there supporting this position -
>>> most to the contrary in fact.
>>
>>
>> Cite 'em.
>
> dude, google 'stainless steel endurance limit'. there are 170,000
> returns, and while i haven't read all of them, the first 50 or so don't
> reference an asymptote - or at least, not without also confusing fatigue
> and endurance limits.
I just did the Google search that you suggested. Since I was looking for
pdfs in the hopes of finding graphics, the first link I clicked was the
5th one on the list:
<http://www.aksteel.com/pdf/markets_products/stainless/austenitic/AK_Nit30PDB_1104_2.pdf>
Look at pages 9 and 10. They show a horizontal portion in the S/N curve.
carl...@comcast.net
[snip]
>How would you design a test for residual stress in spoke elbows? I have
>access to some equipment, but not "neutron/x-ray inferometry" [sic] that
>you mentioned in the above-mentioned thread.
[snip]
Dear Dave,
Here's a stab at it:
http://groups.google.com/group/rec.bicycles.tech/msg/34e3b90b360992f4
After tedious setup explanations, it all boils down to before and
after pictures of four stainless steel spokes whose U-bends have been
tensioned to 0, 76, 121, and 179 kgf, then heated to an orange glow:
http://i12.tinypic.com/2zgtfs5.jpg
http://i11.tinypic.com/2qsc507.jpg
Only one spoke shows any change when stress-relieved by heating, the
untensioned one on the left. This suggests that the other three spokes
had all significant stress removed by tension before they reached
normal bicycle tension levels.
Cheers,
Carl Fogel
dvt
> dvt wrote:
>> How would you design a test for residual stress in spoke elbows? I
>> have access to some equipment, but not "neutron/x-ray inferometry"
>> [sic] that you mentioned in the above-mentioned thread.
>
> chlorides are well known for their stress corrosion in stainless steel.
> google will help you identify other agents as well. simply leave a
> spoke in a jar of the requisite solution and wait.
Thanks for the response, jim.
I see how that tests for corrosion. As I have said in the past, my
metallurgy knowledge is not enough to make the leap from a corrosion
test to a test for residual stress. Maybe you can help me make that
connection.
>>> sure, if residual stress is sufficient to be a factor, it can help to
>>> reduce it. but the necessary supposition that spoke manufacturers
>>> are incompetent in order to take that position is something of a
>>> stretch.
>>
>> I don't think it takes a supposition of incompetence.
>
> i disagree. according to jobstian theory, the supposition is that
> spokes leave the factory with residual stress, ergo the manufacturer is
> incompetent for not relieving it.
I don't think it requires incompetence on the spoke manufacturer's part.
The wheel building process can change the angle of the elbow, producing
some residual stress. I know you have debated that point (with Benjamin
Lewis, if memory serves). His photographs show that it's at least
possible to change the elbow angle by building a wheel, and it agrees
with my experience, so I'm sticking with that. Since we've bent the
spoke elbow without any form of stress relief, there are quite likely
some residual stresses.
So if the manufacturer supplied spokes without residual stress, residual
stresses would be induced during the wheel build. Supplying spokes free
of residual stress would be rather pointless, in that case.
> perhaps, but we'd then have to show that residual stress was a factor
> and that material quality was not.
I think this is where we disagree. The first part of your sentence makes
sense to me, but the second part doesn't. Why does one have to be
exclusive of the other? Why couldn't some failures be caused by a
*combination* of material quality and residual stress?
> seriously, if spoke squeezing was
> able to eliminate fatigue regardless, don't you think manufacturers
> would just do that and use cheaper materials and cheaper processing
> rather than what they do now?
Perhaps if they were able to assume no residual stresses in a spoke in a
built wheel, they *could* go to cheaper materials and processing.
dvt
> On Thu, 02 Nov 2006 09:18:44 -0500, dvt <dvt+u...@psu.edu> wrote:
>
> [snip]
>
>> How would you design a test for residual stress in spoke elbows? I have
>> access to some equipment, but not "neutron/x-ray inferometry" [sic] that
>> you mentioned in the above-mentioned thread.
> Here's a stab at it:
>
> http://groups.google.com/group/rec.bicycles.tech/msg/34e3b90b360992f4
I read that. Is it possible that the modern stainless spokes are
undergoing a phase change (or some other effect) that would affect your
results? For example, could there be a phase change that acts in the
opposite direction of stress relief, resulting in no net change in the
case of higher tension?
I do not know the answer to my questions. So I don't know if your test
is showing *only* stress relief, or if something else is going on as well.
By the way, nice work with the experiment. It was a good idea.
dvt
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> 2. fatigue is statistical. i'm not saying the publishers of this
>>>> paper don't know what they're doing, but be honest peter, there are
>>>> not a lot of other materials out there supporting this position -
>>>> most to the contrary in fact.
>>> Cite 'em.
>> dude, google 'stainless steel endurance limit'. there are 170,000
>> returns, and while i haven't read all of them, the first 50 or so
>> don't reference an asymptote - or at least, not without also confusing
>> fatigue and endurance limits.
> I just did the Google search that you suggested. Since I was looking for
> pdfs in the hopes of finding graphics, the first link I clicked was the
> 5th one on the list:
> <http://www.aksteel.com/pdf/markets_products/stainless/austenitic/AK_Nit30PDB_1104_2.pdf>
>
> Look at pages 9 and 10. They show a horizontal portion in the S/N curve.
Here's another one that shows a S/N curve for 304 SS with an endurance
limit, found via the Google search you suggested:
"Fatigue Life Improvements of the AISI 304 Stainless Steel Ground
Surfaces by Wire Brushing"
Nabil Ben Fredj, Mohamed Ben Nasr, Amir Ben Rhouma, Chedly Braham, and
Habib Sidhom
Journal of Materials Engineering and Performance, Volume 13(5), October
2004, page 565.
Sorry, I can't directly link that one.
carl...@comcast.net
>carl...@comcast.net wrote:
>> On Thu, 02 Nov 2006 09:18:44 -0500, dvt <dvt+u...@psu.edu> wrote:
>>
>> [snip]
>>
>>> How would you design a test for residual stress in spoke elbows? I have
>>> access to some equipment, but not "neutron/x-ray inferometry" [sic] that
>>> you mentioned in the above-mentioned thread.
>
>> Here's a stab at it:
>>
>> http://groups.google.com/group/rec.bicycles.tech/msg/34e3b90b360992f4
>
>I read that. Is it possible that the modern stainless spokes are
>undergoing a phase change (or some other effect) that would affect your
>results? For example, could there be a phase change that acts in the
>opposite direction of stress relief, resulting in no net change in the
>case of higher tension?
>
>I do not know the answer to my questions. So I don't know if your test
>is showing *only* stress relief, or if something else is going on as well.
>
>By the way, nice work with the experiment. It was a good idea.
Dear Dave,
If something else is involved, it's darned clever.
The U-bends of all four spokes were heated to an orange glow.
The U-bend that hadn't been tensioned moved quite noticeably as the
heat relieved internal stresses.
The other three U-bends didn't move, having been tensioned to around
76, 121, and 179 kgf.
Either their stresses had already been relieved by tension below 76
kgf, or some unknown force was holding all three steady, despite twice
as much stress-relieving tension being applied to one spoke.
I'm still trying to poke holes in the experiment.
Two things seem worth checking.
First, I'm going to pre-straighten the elbows on another batch by
bending them instead of pulling on them. Watching the elbows slither
into the holes drilled in the bolts is probably the best part of the
experiment, but it's possible that the smooth straightening of the
elbows as the vise jaws are opened somehow applies lots and lots of
tension briefly, so that there's a hidden stress relief tension.
That is, the 76kgf spoke was just one whose elbow had straightened.
Maybe in straightening it briefly reached 169 kgf?
Second, the pre-straightened elbows may let me test lower tensions,
though the Park tension gauge and the bending wire make that tricky.
If stress is indeed being relieved below 76 kgf, then there should be
a tension level at which the spoke bend-angle changes, but not as much
as large change of the untensioned spoke-bend.
The logic would seem to be that the greatest residual stresses are
going to be relieved first, by the least tension, so I expect a graph
of bend-change versus tension that drops off sharply.
Cheers,
Carl Fogel
Peter Cole
No, the graph (with asymptote) is in:
www.stainless-steel-world.net/pdf/11021.pdf.
> the one showing ~35%
> from the stainless-steel-world link is for DP3, whatever that is.
> and
> fyi, ~35% is indistinguishable from the fatigue limit for a lot of
> structural aluminum alloys, so i don't think you'll find many people
> relying on an endurance limit for DP3 in their fatigue design.
The endurance limit I referred to was for 316. The ratio of the
endurance limit to tensile strength for 316 according to the sources
above is 44%.
>>> 2. fatigue is statistical. i'm not saying the publishers of this
>>> paper don't know what they're doing, but be honest peter, there are
>>> not a lot of other materials out there supporting this position -
>>> most to the contrary in fact.
>>
>>
>> Cite 'em.
>
> dude, google 'stainless steel endurance limit'. there are 170,000
> returns, and while i haven't read all of them, the first 50 or so don't
> reference an asymptote - or at least, not without also confusing fatigue
> and endurance limits. it's been years since you and i first started
> this kind of debate, and so far you've cited just one link with a
> graphical asymptote. everything else shows a more typical flattening
> curve, no asymptote. done any curve fitting exercises lately?
Quibbling about terminology aside, all 3 of the sources I cited:
http://users.wpi.edu/~cfurlong/me3320/lect13/Lect13.pdf
bama.ua.edu/~mweaver/courses/MTE455/MTE455_2006_L26.pdf
http://www.kuleuven.ac.be/bwk/materials/Teaching/master/wg12/l0200.htm#SEC_6_1
unambiguously discussed S/N curves where the materials had infinite
stress life (horizontal asymptote). There was no confusion about the
topic. 2 of the authors contended that all stainless steels have this
characteristic, the 3rd said some.
The last source I cited: www.stainless-steel-world.net/pdf/11021.pdf,
showed a S/N curve for a specific alloy (which you requested), that of
the very common 316.
Do you have any examples of S/N curves that dispute this? Say one for 316?
And I'd appreciate you stop calling me "dude".
Peter Cole
I think you are confusing techniques for completely removing (bulk)
residual stresses from those designed only to remove very localized
residual stresses. An example of the latter is given below. The
technique is identical (except for scale) as that for stress relieving
spokes.
"Subpart 54.30—Mechanical Stress
Relief
§ 54.30–1 Scope.
(a) Certain pressure vessels may be
mechanically stress relieved in accordance
with the requirements in this subpart.
(b) [Reserved]
§ 54.30–3 Introduction.
(a) Large conventional pressure vessels
used to transport liquefied petroleum
and natural gases, at ‘‘low temperatures’’
may often be difficult to
thermally stress relieve. Where no
other problem, such as corrosion exists,
mechanical stress relief will be
permitted for Class II–L pressure vessels.
(b) Mechanical stress relief serves to
cause small flaws, particularly in the
weld zone, to yield plastically at the
flaw tip resulting in a local relief of
stress and a blunting of the crack tip.
To achieve the maximum benefit from
mechanical stress relief, it is necessary
that the stresses so imposed be more
severe than those expected in normal
service life. At the same time, it is necessary
that the stresses which are imposed
are not so high as to result in appreciable
deformation or general yielding."
"§ 54.30–10 Method of performing mechanical
stress relief.
(a) The mechanical stress relief shall
be carried out in accordance with the
following stipulations using water as
the pressurizing medium:
(1) At a hydrostatic pressure (measured
at the tank top) of 11⁄2 times the
design pressure. (See UA–60(e) of the
ASME Code.)
(2) At a temperature of 70 °F. or the
service temperature plus 50 °F., whichever
is higher. Where the ambient temperature
is below 70 °F., and use of
water at that temperature is not practical,
the minimum temperature for
mechanical stress relief may be below
70 °F. but shall not be less than 50 °F.
above service temperature.
(3) The stress relief shall be at the required
temperature and pressure and
held for a period not less than 2 hours
per inch of metal thickness, but in no
case less than 2 hours."
carl...@comcast.net
<peter...@comcast.net> wrote:
[snip]
>(3) The stress relief shall be at the required
>temperature and pressure and
>held for a period not less than 2 hours
>per inch of metal thickness, but in no
>case less than 2 hours."
Dear Peter,
This is the first time that I've seen a time versus metal thickness
aspect of mechanical stress relief.
Two hours per inch of metal thickness works out to 7200 seconds per
25.4 mm, or 283 seconds per millimeter.
That would be about 10 to 12 minutes for a 2 mm thick spoke, but I
assume that the shape, absolute pressure, and absolute thickness would
modify that naive calculation considerably.
Still, it seems to be a few orders of magnitude longer than most wheel
builders squeeze their spokes.
Do you know of anything that might shed light on the effect of the
length of time that spokes are squeezed together?
Right now, I'm using a vise-rig to stretch spokes, but they're being
left on the rack, so to speak, for much longer than I can hope to
squeeze with my bare hand.
Cheers,
Carl Fogel
jim beam
> jim beam wrote:
>> dvt wrote:
>>> How would you design a test for residual stress in spoke elbows? I
>>> have access to some equipment, but not "neutron/x-ray inferometry"
>>> [sic] that you mentioned in the above-mentioned thread.
>>
>> chlorides are well known for their stress corrosion in stainless
>> steel. google will help you identify other agents as well. simply
>> leave a spoke in a jar of the requisite solution and wait.
>
> Thanks for the response, jim.
>
> I see how that tests for corrosion. As I have said in the past, my
> metallurgy knowledge is not enough to make the leap from a corrosion
> test to a test for residual stress. Maybe you can help me make that
> connection.
long, long and highly specialized subject, but basically, there's a
synergy/susceptibility between certain materials and certain
environmental factors that lead to a specific form of corrosion.
materials that may be passive in an unstressed state, can become highly
susceptible to localized corrosion when stressed. certain
material/reagent pairs exhibit dramatic crack propensity. examples
include http://www.corrosion-doctors.org/Forms/scc-environments.htm
>
>>>> sure, if residual stress is sufficient to be a factor, it can help
>>>> to reduce it. but the necessary supposition that spoke
>>>> manufacturers are incompetent in order to take that position is
>>>> something of a stretch.
>>>
>>> I don't think it takes a supposition of incompetence.
>>
>> i disagree. according to jobstian theory, the supposition is that
>> spokes leave the factory with residual stress, ergo the manufacturer
>> is incompetent for not relieving it.
>
> I don't think it requires incompetence on the spoke manufacturer's part.
> The wheel building process can change the angle of the elbow, producing
> some residual stress.
well, i don't agree with the "correcting the spoke line" practice for
exactly this reason. most hub flanges are canted and drilled so that
spoke angles are optimum for their exit geometry.
http://www.flickr.com/photos/38636024@N00/104463818/
to "correct the spoke line" /prior/ to raising spoke tension
sufficiently to bed the spokes fully into the hub not only leaves the
spoke elbow with a non-factory angle, it can indeed introduce residual
stress into an otherwise optimized component.
> I know you have debated that point (with Benjamin
> Lewis, if memory serves). His photographs show that it's at least
> possible to change the elbow angle by building a wheel, and it agrees
> with my experience, so I'm sticking with that. Since we've bent the
> spoke elbow without any form of stress relief, there are quite likely
> some residual stresses.
i've built wheels and have "stress relieved" them using the "mavic
method" [block of wood and leaning on the rim] and have subsequently
disassembled them. there may have been some elbow angle change, but
it's not one i have been able to see in comparison with new spokes.
granted, you need to be careful to achieve this, but it seems possible.
>
> So if the manufacturer supplied spokes without residual stress, residual
> stresses would be induced during the wheel build. Supplying spokes free
> of residual stress would be rather pointless, in that case.
i disagree. no manufacturer that cares about their reputation enough to
put their name on their product is going to risk damage to sales by
shipping something they know to be a problem. otherwise why bother with
the considerable expense of vacuum degassed steels as well?
>
>> perhaps, but we'd then have to show that residual stress was a factor
>> and that material quality was not.
>
> I think this is where we disagree. The first part of your sentence makes
> sense to me, but the second part doesn't. Why does one have to be
> exclusive of the other? Why couldn't some failures be caused by a
> *combination* of material quality and residual stress?
they could, but why spend your time fixing the hubcap if the fan belt's
broken?
>
>> seriously, if spoke squeezing was able to eliminate fatigue
>> regardless, don't you think manufacturers would just do that and use
>> cheaper materials and cheaper processing rather than what they do now?
>
> Perhaps if they were able to assume no residual stresses in a spoke in a
> built wheel, they *could* go to cheaper materials and processing.
doesn't work that way in practice. real world usage is that material
quality /does/ affect failure rate. spoke squeezing has no quantified
efficacy that i've ever seen.
jim beam
hmmm. the test procedure is familiar, that rationale is not. welds are
subject to discontinuities and flaws. if a crack or flaw is present,
raising the stress to a level sufficient to cause failure will expose it
- as predicted by fracture mechanics. on large pressure vessels that
are difficult to otherwise test, this is about the only way to be sure.
testing is performed not only prior to deployment, but periodically in
use to ensure any fatigue crack that has grown over critical will fail
in testing, not use.
http://www.inl.gov/materialscience/fracture.shtml
i've not seen any analysis that supports this process as a "stress
relief" rationale.
jim beam
support their curve fit!
context: this is a marketing piece aimed at engineers - engineers, for
some reason that is still unclear to me, seem to be fixated with
endurance limits. fact is, it's /highly/ dangerous to design with
endurance limits in mind - they are /not/ reliable.
i'm willing and able to accept new data if it's available, but back in
the day when i used to do this stuff, stainless wasn't attributed with
an endurance limit because there was no interstitial diffusion mechanism
to support it. maybe things have changed, but i doubt it.
jim beam
that last one is great in that slide 4 shows crack initiation at an
inclusion - the reason why we degas steels for maximum fatigue resistance.
but that's tangential. otherwise i see repeated confusion between
endurance limit and fatigue limit. there's not much chance for an
engineer to get this stuff right if they're not being taught correctly
in the first place.
>
>
> unambiguously discussed S/N curves where the materials had infinite
> stress life (horizontal asymptote). There was no confusion about the
> topic. 2 of the authors contended that all stainless steels have this
> characteristic, the 3rd said some.
there is no confusion about fatigue peter - don't say there is. what i
am questioning is the mechanism by which stainless steels are alleged to
have endurance limits. in mild steels, it's diffusion of carbon - a
well known and researched mechanism. in stainless, what is it? just
making a curve fit assumption doesn't do it for me.
>
> The last source I cited: www.stainless-steel-world.net/pdf/11021.pdf,
> showed a S/N curve for a specific alloy (which you requested), that of
> the very common 316.
>
> Do you have any examples of S/N curves that dispute this? Say one for 316?
http://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6878/cr-6878-est-fatigue-end.pdf
>
> And I'd appreciate you stop calling me "dude".
du^H^, oh, never mind.
Peter Cole
Here's an almost 50 year old NASA paper that shows endurance limit for
stainless.
ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19640015138_1964015138.pdf
Peter Cole
I see nothing in that paper to support your position, or even anything
relevant to this thread. Perhaps you could point out the sections.
jim beam
at elevated temperatures!!!
which leads me back to the question i originally asked - what is the
mechanism for endurance limit in stainless? you get endurance in mild
steel at ambient because the diffusion coefficient of carbon is
sufficiently high to allow dislocation locking. what's going on here?
this paper is just an engineering test - there is no material or
mechanism investigation whatsoever.
jim beam
5.1 - curve fit. no knee.
Peter Cole
I have no idea what the mechanism is, but it seems that an endurance
limit in stainless is a well-known phenomenon and has been for many years.
Peter Cole
The "ANL statistical model" that you refer to is explicitly for
low-cycle, high stress fatigue. That should be obvious from the
equation, if not, you could consult an earlier paper by the same author
which says:
"The ANL statistical model is recommended for predicting fatigue lives
that are <106 cycles."
<http://www.osti.gov/bridge/servlets/purl/10546-mpWKBW/webviewable/10546.pdf>
dvt
> i disagree. no manufacturer that cares about their reputation enough to
> put their name on their product is going to risk damage to sales by
> shipping something they know to be a problem. otherwise why bother with
> the considerable expense of vacuum degassed steels as well?
Do spoke manufacturers use vacuum degassed steel?
>>> perhaps, but we'd then have to show that residual stress was a factor
>>> and that material quality was not.
>> I think this is where we disagree. The first part of your sentence
>> makes sense to me, but the second part doesn't. Why does one have to
>> be exclusive of the other? Why couldn't some failures be caused by a
>> *combination* of material quality and residual stress?
> they could, but why spend your time fixing the hubcap if the fan belt's
> broken?
The hubcap and fan belt are not related. Residual stress and material
quality may work together to cause the failure under discussion. I have
seen no proof that they are related, and I have seen no proof that they
are *not* related.
>>> seriously, if spoke squeezing was able to eliminate fatigue
>>> regardless, don't you think manufacturers would just do that and use
>>> cheaper materials and cheaper processing rather than what they do now?
>>
>> Perhaps if they were able to assume no residual stresses in a spoke in
>> a built wheel, they *could* go to cheaper materials and processing.
>
> doesn't work that way in practice. real world usage is that material
> quality /does/ affect failure rate. spoke squeezing has no quantified
> efficacy that i've ever seen.
Aye, there we agree. No one has published a study that shows the
efficacy of spoke squeezing, and no one has published a study regarding
material quality in spoke elbows. As you said in another thread long
ago, we don't know what we don't know.
jim beam
> jim beam wrote:
>> i disagree. no manufacturer that cares about their reputation enough
>> to put their name on their product is going to risk damage to sales by
>> shipping something they know to be a problem. otherwise why bother
>> with the considerable expense of vacuum degassed steels as well?
>
> Do spoke manufacturers use vacuum degassed steel?
>
>>>> perhaps, but we'd then have to show that residual stress was a
>>>> factor and that material quality was not.
>
>>> I think this is where we disagree. The first part of your sentence
>>> makes sense to me, but the second part doesn't. Why does one have to
>>> be exclusive of the other? Why couldn't some failures be caused by a
>>> *combination* of material quality and residual stress?
>
>> they could, but why spend your time fixing the hubcap if the fan
>> belt's broken?
>
> The hubcap and fan belt are not related.
that's my point - one will stop the car working, the other, although it
has a function in other aspects of vehicle use, doesn't. "residual
stress", it must be assumed, is a constant since spokes are made the
same way today as they were in the old days. it's only the introduction
of more fatigue resistant material that has impacted failure rates. the
practice of spoke squeezing, bedding in, "stress relief", whatever you
call it, has been around since the advent of the wire-spoked wheel.
> Residual stress and material
> quality may work together to cause the failure under discussion. I have
> seen no proof that they are related, and I have seen no proof that they
> are *not* related.
as above, if the only variable is material but all other production
factors are constant, and we get different results, we /have/ to
conclude that whatever effect residual stress may be having, it's as
important as the hubcap.