Butted vs. straight-gauge spokes
Joseph Kubera
I need to have wheels built (my choice of parts) for the new bike, and figured
the local shop could do it since I'm asking them to build the bike anyway.
So I requested butted SS spokes, say 14-15, because I have read that a lot of
nice wheels are built this way. The shop guy was surprised. He said they cost
twice as much and don't hold up as well, and didn't recommend them.
Any thoughts on this? BTW, I was going to use 32 front and 36 rear Torelli
Masters. An all-around road bike. I weigh 180, if that matters.
Thanks.
Joe
Drew Eckhardt
Joseph Kubera <kub...@aol.com> wrote:
>So I requested butted SS spokes, say 14-15, because I have read that a lot of
>nice wheels are built this way. The shop guy was surprised. He said they cost
>twice as much and don't hold up as well, and didn't recommend them.
Butted spokes (even DT Revolutions although they're harder to build with) hold
up fine and build into a stronger wheel than straight-gauged as explained in
_The Bicycle Wheel_ by Jobst Brandt.
Personally, if I didn't build my own wheels I wouldn't trust people
parotting such superstitions to do it for me.
>Any thoughts on this? BTW, I was going to use 32 front and 36 rear Torelli
>Masters. An all-around road bike. I weigh 180, if that matters.
With a beer gut I weigh 175. In spite of jumping off curbs with said belly,
a back pack, and 23mm Continentals 32 hole Mavic Reflex rims laced cross-3
with 14/15 spokes on the rear drive side and DT revos elsewhere hold up fine
(as in don't go out of true);
--
<a href="http://www.poohsticks.org/drew/">Home Page</a>
The Congress shall assemble at least once in every Year, and such Meeting
shall be on the first Monday in December, unless they shall by Law appoint a
different Day.
Mike Krueger
of
nice wheels are built this way. The shop guy was surprised. He said they cost
twice as much and don't hold up as well, and didn't recommend them.
Any thoughts on this? BTW, I was going to use 32 front and 36 rear Torelli
Masters. An all-around road bike. I weigh 180, if that matters. >>
Straight gauge spokes are preferred when wheels need to be build quickly and
when maximum rigidity is necessary. Butted spokes will "give" a little under
load, which results in a wheel that is more comfortable to ride, and actually
more durable over the long term. Swaging the spokes work-hardens them,
increasing their strength. And, of course, butted spokes are lighter and
slightly more aerodynamic.
Double butted spokes only cost pennies more than straight gauge. It is always
easier and faster to build wheels with straight gauge. Evidently, the guy at
the shop doesn't have the time or the expertise to do it right. Maybe you
should look for someone else.
I weigh the same as you, 180. My wheels are all 32 hole in the back with
14/15/14 db spokes. In front, I ride the same set-up, or 15/16/15g for a little
lighter wheel. I use brass nips and a sensible lacing pattern (3 cross). No
problems in tens of thousands of miles ridden.
Benjamin Lewis
> Hi, all.
>
> I need to have wheels built (my choice of parts) for the new bike, and
> figured the local shop could do it since I'm asking them to build the
> bike anyway.
>
> So I requested butted SS spokes, say 14-15, because I have read that a
> lot of nice wheels are built this way. The shop guy was surprised. He
> said they cost twice as much and don't hold up as well, and didn't
> recommend them.
>
> Any thoughts on this?
Find a new shop guy.
--
Benjamin Lewis
"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening
David Ornee
"Joseph Kubera" <kub...@aol.com> wrote in message
news:20030128220131...@mb-mp.aol.com...
In his article at URL http://www.sheldonbrown.com/wheelbuild.html Sheldon
Brown says:
"Double-butted spokes do more than save weight. The thick ends make them as
strong in the highly-stressed areas as straight-gauge spokes of the same
thickness, but the thinner middle sections make the spokes effectively more
elastic. This allows them to stretch (temporarily) more than thicker spokes.
As a result, when the wheel is subjected to sharp localized stresses, the
most heavily stressed spokes can elongate enough to shift some of the stress
to adjoining spokes. This is particularly desirable when the limiting factor
is how much stress the rim can withstand without cracking around the spoke
hole."
The points that Jobst Brandt makes are:
"Butted spokes..... give more durable wheels. They are more elastic than
unbutted spokes because their thin mid-sections stretch more and they can be
made just as tight as unbutted spokes. Under load, they resist loosening
better than straight spokes. Their resilience helps the rim distribute
loads over more spokes and reduces peak stress changes. Butted spokes are
lighter without giving up any strength."
In the back of Jobst Brant's book under "SPOKE STRENGTH" Jobst goes on to
say:
"The results show that there is little measurable difference in strength
among these spokes (DT unbutted, DT butted, Wheelsmith unbutted, and
Wheelsmith butted) and suggest that their differences, if any, lie in
fatigue characteristics that depend on their alloy, temper, butting, and how
they are built into a wheel."
Jobst's last point "how they are built into a wheel" , in my opinion, makes
the most significant difference in the reliability of the wheel.
David Ornee, Western Springs, IL
A Muzi
Everyone has their opinion but few share that of your LBS, who seems not to
be familar with the building of bicycle wheels. Will they build as you
require? If not, is there another shop nearby?
Brandt's The Bicycle Wheel, page 46-7:
of swadged spokes, "The diameter reduction increases spoke elasticity,
increases strength by work hardening, and reduces weight. However, the most
valuable contribution of swadging is that peak stresses are absorbed in the
straight midsection rather than concentrated in the threads and elbow,
thereby substantially reducing fatigue failures."
--
Andrew Muzi
http://www.yellowjersey.org
Open every day since 1 April 1971
David L. Johnson
> Joseph Kubera wrote:
>
>> Hi, all.
>>
>> I need to have wheels built (my choice of parts) for the new bike, and
>> figured the local shop could do it since I'm asking them to build the
>> bike anyway.
>>
>> So I requested butted SS spokes, say 14-15, because I have read that a
>> lot of nice wheels are built this way. The shop guy was surprised. He
>> said they cost twice as much and don't hold up as well, and didn't
>> recommend them.
>>
>> Any thoughts on this?
>
> Find a new shop guy.
>
Agreed. There is one reason why many shops recommend straight-gauge
spokes. They have a machine that cuts spokes to length, and rolls
threads. That way, they stock a bunch of long, straight-gauge spokes and
cut them to size as needed, rather than stocking lots of sizes. Butted
spokes obviously can't be re-cut, except for small changes.
The issue is shop inventory, not performance. I agree with Sheldon that
butted spokes build up a more durable wheel. They cost a little more,
not twice as much. Fer instance, Nashbar sells packs of 20 14/15 spokes
for $12.95, 14 gauge for $8.95, Actually, I think that $12.95 is a bit
high, and you can probably do better.
Speaking of doing better, find another shop, someone who won't try to
blow smoke up your ass.
--
David L. Johnson
__o | Some people used to claim that, if enough monkeys sat in front
_`\(,_ | of enough typewriters and typed long enough, eventually one of
(_)/ (_) | them would reproduce the collected works of Shakespeare. The
internet has proven this not to be the case.
A Muzi
lot
> of
> nice wheels are built this way. The shop guy was surprised. He said they
cost
> twice as much and don't hold up as well, and didn't recommend them.
> Any thoughts on this? BTW, I was going to use 32 front and 36 rear
Torelli
> Masters. An all-around road bike. I weigh 180, if that matters. >>
"Mike Krueger" <skub...@aol.com> , gilding the lily, wrote in message
news:20030128230600...@mb-fw.aol.com...
> Straight gauge spokes are preferred when wheels need to be build quickly
and
> when maximum rigidity is necessary. Butted spokes will "give" a little
under
> load, which results in a wheel that is more comfortable to ride, and
actually
> more durable over the long term. Swaging the spokes work-hardens them,
> increasing their strength. And, of course, butted spokes are lighter and
> slightly more aerodynamic.
> Double butted spokes only cost pennies more than straight gauge. It is
always
> easier and faster to build wheels with straight gauge. Evidently, the guy
at
> the shop doesn't have the time or the expertise to do it right. Maybe you
> should look for someone else.
> I weigh the same as you, 180. My wheels are all 32 hole in the back with
> 14/15/14 db spokes. In front, I ride the same set-up, or 15/16/15g for a
little
> lighter wheel. I use brass nips and a sensible lacing pattern (3 cross).
No
> problems in tens of thousands of miles ridden.
I bet you cannot "feel" the "comfort" of a butted spoke versus a straight
one.
I'd bet real money on that, actually. Wheels are a rigid figure for these
purposes.
And I don't know about you but I build as fast with the more flexible butted
ones. Certainly not any slower.
Drew Eckhardt
If you compress the wheel enough to unload spokes the rim can move off the
centerline. When tension is re-applied in that state, the wheel turns into
a pringle.
Tension is limitted by the rim strength, so both thin and thick spokes will
start at the same tension in a well-built wheel.
However thinner spokes stretch more at a given tension; so you need to compress
the rim more to make them slack. That in turn requires more force, so it takes
a bigger blow to destroy a thin-spoked wheel than a thick.
A butted spoke has the thick spoke's strength in the threads, but builds into
a wheel that otherwise shares the thin-spoked wheel's superior characteristics.
Tim McNamara
kub...@aol.com (Joseph Kubera) wrote:
> So I requested butted SS spokes, say 14-15, because I have read
> that a lot of nice wheels are built this way. The shop guy was
> surprised. He said they cost twice as much and don't hold up as
> well, and didn't recommend them.
>
> Any thoughts on this?
He's right, they cost about twice as much. He's also ignorant if he
thinks they don't hold up as well as butted spokes. Get your wheels
built elsewhere, by someone who actually knows stuff like this.
Mark Janeba
> Agreed. There is one reason why many shops recommend straight-gauge
> spokes. They have a machine that cuts spokes to length, and rolls
> threads. That way, they stock a bunch of long, straight-gauge spokes and
> cut them to size as needed, rather than stocking lots of sizes. Butted
> spokes obviously can't be re-cut, except for small changes.
Agree with everything else, but I have to ask about the above: Have you
really seen lots of shops with spoke cutters? I've seen one, and they
didn't use the cutter.* Maybe you frequent a better-equipped class of
shops than I do. Are shops who really use these cutters that common?
Wouldn't the labor costs exceed the inventory costs? (I'm beginning to
think that shops who build wheels are becoming rare.)
*Amusing tech trivia/nostalgia bit: Long ago, I had a Claud Butler
tandem (late 40's early 50's was my best estimate of its birthdate), the
model with the ultra-short chainstay and curved seat tube. It had
huge-flanged 3-piece airlite hubs with 13-14 single-butt spokes - 13g at
the hub, 14g at the rim. When I got the bike, it had Dunlop steel
clincher rims. I set the bike up as fixed gear for fooling around at
the velodrome, and wanted a better rim (sewup? hook-bead? can't recall,
we were just fooling around, after all). This required shorter
spokes, and I couldn't find anybody selling 13-14g spokes at the time,
so off to the shops to see who had a spoke cutter. Found a shop with
one (Eldi, IIRC), and arranged to use it (the folk there didn't seem to
want to touch the tool OR the spokes). It was a cutter and not a
roller, but it did tolerably well. Sold the bike many years ago; I
think I've since seen 13-14 spokes advertised.
PS - If anyone can better date that Butler (those chainstays were very
distinctive, you'd remember it if you'd seen them), I'd love to hear it.
If anyone wants to buy that Dunlop rim, I'd love to hear that too.
Back to the present day, (and are shops using those spoke cutters that
common?)
--
Mark Janeba
remove antispam phrase in address to reply
Qui si parla Campagnolo
lot of
nice wheels are built this way. The shop guy was surprised. He said they cost
twice as much and don't hold up as well, and didn't recommend them.
Don't cost twice as much and double butted spokes make a more durable wheel,
all other things being equal.
Sounds like he may have a bunch of straight gauge spokes and doesn't want to
but DB ones..
<< Any thoughts on this? BTW, I was going to use 32 front and 36 rear Torelli
Masters. An all-around road bike. I weigh 180, if that matters.
GREAT choice, hopefully the gent knows what he is doing, wheelbuuild wise..
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
Paul Kopit
Angeles area maybe $,50/straight and $.75 butted.
I read here many times that technically the butted spokes are a better
choice. Personally, I see no difference in my wheels. I frequently
use straight 14 ga. on drive side and straight 15 elsewhere. I weigh
200 lbs.
My personal gripe about the Torelli Master is that it seemed more
difficult to mount tires on. I have not had that problem with other
rims and take off and mount everything w/o tools.
Paul Kopit
need for the 2nd butting at the threaded end is necessary in the first
place. Spokes don't seem to break there.
Paul Kopit
the Phil Wood machine $2,400. Where it does pay is on providing
service and having any spoke length you want in stock. As more wheels
come factory built, you'll see even less demand for the machine. Most
shops do not have one.
Alex Rodriguez
>I need to have wheels built (my choice of parts) for the new bike, and figured
>the local shop could do it since I'm asking them to build the bike anyway.
>
>So I requested butted SS spokes, say 14-15, because I have read that a lot of
>nice wheels are built this way. The shop guy was surprised. He said they
cost
>twice as much and don't hold up as well, and didn't recommend them.
If he is recommending straight gauge instead of double butted, that is a
good indication that this person is not the one you want building your
wheels.
-----------------
Alex __O
_-\<,_
(_)/ (_)
David L. Johnson
> David L. Johnson
>
>> Agreed. There is one reason why many shops recommend straight-gauge
>> spokes. They have a machine that cuts spokes to length, and rolls
>> threads. That way, they stock a bunch of long, straight-gauge spokes
>> and cut them to size as needed, rather than stocking lots of sizes.
>> Butted spokes obviously can't be re-cut, except for small changes.
>
>
> Agree with everything else, but I have to ask about the above: Have you
> really seen lots of shops with spoke cutters? I've seen one, and they
> didn't use the cutter.* Maybe you frequent a better-equipped class of
> shops than I do.
Or maybe not. I have seen one shop locally that used a cutter/roller.
They were also pushing straight-gauge spokes, which is odd. They are now
out of business, and I buy spokes on the net.
> Are shops who really use these cutters that common?
Depends on their clientele. This shop did a lot of tri business. Maybe
they have a lot of spoke sizes to worry about, with the common 650c
wheel. I don't really know, though.
> Wouldn't the labor costs exceed the inventory costs? (I'm beginning to
> think that shops who build wheels are becoming rare.)
They would use cheap spokes to begin with, made even cheaper by the lack
of threads and bulk discounts. Once you buy the tool, cutting and
rolling is quite quick.
--
David L. Johnson
__o | As far as the laws of mathematics refer to reality, they are not
_`\(,_ | certain, and as far as they are certain, they do not refer to
(_)/ (_) | reality. -- Albert Einstein
S. Anderson
say, I've never been happy cutting and threading spokes, either with the
process or the product. I would never, EVER, do it unless I absolutely had
to. I guess if you have a lot of time and patience I can see it, but to me,
it was just a big PITA. This may sound terrible, but I'd never cut spokes
if they made them somewhere, especially if it was the customer's money, not
mine. I'd save them cash in a lot of other ways when I could, but cutting
and threading would definitely not be at the top of my list.
My $0.02CDN worth,
Scott..
--
Scott Anderson
"David L. Johnson >" <David L. Johnson <david....@lehigh.edu> wrote in
message news:b19u8l$i...@fidoii.CC.Lehigh.EDU...
> On Wed, 29 Jan 2003 02:47:35 -0500, Mark Janeba wrote:
>
<<snip>>
David Green
>
> I need to have wheels built (my choice of parts) for the new bike, and
figured
> the local shop could do it since I'm asking them to build the bike anyway.
>
> So I requested butted SS spokes, say 14-15, because I have read that a lot
of
> nice wheels are built this way. The shop guy was surprised. He said they
cost
> twice as much and don't hold up as well, and didn't recommend them.
>
> Any thoughts on this?
Sounds like this guy isn't that knowledgeable about wheel building. Go
elsewhere, or build your own.
A better builder ought to be recommending that you use:
-stainless double-butted spokes, brass nipples, 36 hole 3-cross
-decent alloy rims, with double-walls and full eyelets
David Green
Cambridge UK
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DON'T MAIL THE REPLY ADDRESS! Before you click 'Send',
replace 'deadspam.com' with 'onetel.net.uk'.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Wayne T
because I was told that these spokes are more dependable under touring
loads. Now it sounds like most posters here feel that double butted wheels
are at least as strong or maybe stronger. My builder who is converting my
bike to cassette and will be rebuilding my rear wheel, feels that I should
go with double butted. I weigh a little under 180. Used to go up to 195,
but no more. Since the front wheel doesn't need to be rebuilt, it will
remain 14 gauge straight gauge 36 spoked wheel. What is the primary reason
for double butted wheels? I would think weight savings. How much savings
would that be?
"Drew Eckhardt" <dr...@revolt.poohsticks.org> wrote in message
news:g7i71b....@revolt.poohsticks.org...
David Ornee
Building", Gerd Schraner at URL:
http://www.dtswiss.com/en/laufradbau-faq.html
"The use of these butted ("reduced") spokes allow longer-life wheels to be
built. Spokes with a thinner mid-section aren't just lighter and more
aerodynamic but, more importantly, are much more elastic than normal
straight-edged spokes. When placed under extreme overloads, they react in a
similar way to resilient bolts used in the machine industry.
If a wheel undergoes rapid radial forces, for example a bump, the spokes
spring as they take up the overload, thus protecting the hub" (and rim ...
my addition).
Butted spokes are not stronger, but when properly built, will make for a
more durable wheel.
A properly built wheel includes proper tensioning, spoke alignment, tension
balancing, and stress relieving.
Suggested reading "the Bicycle Wheel" by Jobst Brandt.
Weight savings and aerodynamic improvements are small, but positive
by-products.
David Ornee, Western Springs, IL
"Wayne T" <wdu...@ucwphilly.rr.com> wrote in message
news:a5W0a.50$ji.1...@twister.southeast.rr.com...
A Muzi
news:a5W0a.50$ji.1...@twister.southeast.rr.com...
> for double butted wheels? I would think weight savings. How much savings
> would that be?
The weight savings is insignificant.
A frequently quoted passage from The Book is found on page 47:" . . . the
most valuable contribution of swadging is that peak stresses are absorbed in
the straight midsection rather than concentrated in the threads and elbow,
thereby substantially reducing fatigue failures."
As a matter of fact, that passage was mentioned twice and quoted once in
this very thread a few days ago.
The Pomeranian
Mark Hickey
>I've always used 14 gauge straight gauge 36 spoke wheels on my touring bike
>because I was told that these spokes are more dependable under touring
>loads. Now it sounds like most posters here feel that double butted wheels
>are at least as strong or maybe stronger. My builder who is converting my
>bike to cassette and will be rebuilding my rear wheel, feels that I should
>go with double butted. I weigh a little under 180. Used to go up to 195,
>but no more. Since the front wheel doesn't need to be rebuilt, it will
>remain 14 gauge straight gauge 36 spoked wheel. What is the primary reason
>for double butted wheels? I would think weight savings. How much savings
>would that be?
The other posters hit most of the real reasons for going with butted
spokes. If you're still curious about how much weight you'll save -
assuming you use DT spokes and change the wheel from 2.0mm (14g) to
2.0/1.8mm (14/15g), expect to save about 70 grams (or about 2.5
ounces). Not a huge amount, but hey - it's one of those rare times
when you end up with something lighter AND stronger (though certainly
not cheaper).
Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame
Qui si parla Campagnolo
for double butted wheels?
More durable, longer lasting wheel, all other things being equal.
<< I would think weight savings. How much savings
would that be?
Nope, not weight savings..durability.
Wayne T
"Qui si parla Campagnolo" <vecc...@aol.com> wrote in message
news:20030208091700...@mb-md.aol.com...
> Wayne-<< What is the primary reason
> for double butted wheels?
>
> More durable, longer lasting wheel, all other things being equal.
>
> << I would think weight savings. How much savings
> would that be?
>
> Nope, not weight savings..durability.
Is this also true under heavy touring circumstances?
AndyMorris
Yes for reasons that Jobst explains in his excelent book, far better than i
could hope to do.
--
Andy Morris
AndyAtJinkasDotFreeserve.Co.UK
Love this:
Put an end to Outlook Express's messy quotes
http://home.in.tum.de/~jain/software/oe-quotefix/
jobst....@stanfordalumni.org
>>> What is the primary reason for double butted wheels?
>> More durable, longer lasting wheel, all other things being equal.
>>> I would think weight savings. How much savings would that be?
>> Nope, not weight savings... durability.
> Is this also true under heavy touring circumstances?
The wheel does not know what the intent of the bicycle ride is and how
continuous the use will be. Therefore, whether touring racing or
weekend rides makes no difference as far as spokes go. Load limit is
given by spoke tension. Spoke tension is limited by the rim, not the
spokes. If you are concerned with cracking the rim, then that is
reduced by using thinner swaged spokes, the thinner the better.
Jobst Brandt
jobst....@stanfordalumni.org
Palo Alto CA
Wayne T
"AndyMorris" <AndyM...@DeadSpam.com> wrote in message
news:b248mo$orj$2...@newsg2.svr.pol.co.uk...
> Wayne T wrote:
> > "Qui si parla Campagnolo" <vecc...@aol.com> wrote in message
> > news:20030208091700...@mb-md.aol.com...
> >> Wayne-<< What is the primary reason
> >> for double butted wheels?
> >>
> >> More durable, longer lasting wheel, all other things being equal.
> >>
> >> << I would think weight savings. How much savings
> >> would that be?
> >>
> >> Nope, not weight savings..durability.
> >
> > Is this also true under heavy touring circumstances?
> >
> >>
> >>
> >> Peter Chisholm
> >> Vecchio's Bicicletteria
> >> 1833 Pearl St.
> >> Boulder, CO, 80302
> >> (303)440-3535
> >> http://www.vecchios.com
> >> "Ruote convenzionali costruite eccezionalmente bene"
>
> Yes for reasons that Jobst explains in his excelent book, far better than
i
> could hope to do.
And to think that all this time I thought that straight gauge was the only
way to go for heavy touring because it was stronger. Now I find that the
opposite is true. Thanks everyone, I've learned something new. Or should I
say I've relearned?
Wayne T
<jobst....@stanfordalumni.org> wrote in message
news:Udi1a.65119$Ik.26...@typhoon.sonic.net...
Actually, I was concerned with breaking spokes and was wondering if a bike
weighed down with 50 to 75 pounds of touring gear would be less apt to have
spoke breakage with 14/15 double butted spokes VS straight 14 gauge
Qui si parla Campagnolo
Yep-just more spokes, heavier rim...but still dbl butts.
Paul Kopit
straight 14 ga vs butted 14/15 or is the difference theory.
Recently there was a post suggesting that wheels using butted spokes
could be built to higher tension w/o spoke pull through. How does the
nipple know what size spoke is pulling it?
I recall that using a larger number of thinner spokes makes better
wheels but not necessarily butted spokes.
Sheldon Brown
I was hard to convince, favored straight gauge for a long time, but
eventually I noticed a high correlation between rims cracking around the
spoke holes and the use of straight 2 mm spokes.
When riding conditions apply extra stress to one spoke, and that spoke
can stretch a bit, part of the stress is passed along and shared with
adjacent spokes. If the spoke can't stretch, the full stress is applied
to the rim at the one spoke hole.
Sheldon "The Willow, Not The Oak" Brown
+-------------------------------------------------------------------+
| The secrets of flight will not be mastered within our lifetime… |
| …not within a thousand years –Wilbur Wright, 1901 |
+-------------------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
jobst....@stanfordalumni.org
> I'm agnostic. Has anyone really seen any difference in a wheel with
> straight 14 ga vs butted 14/15 or is the difference theory.
This would require a life test on a machine for both types of spoke,
something the industry has not been doing since wire spoked wheels
were first used. The use of strain bolts in industry in general has
been shown to have major advantage, but then the machines themselves
are the life test. Bicycle riders are not a sufficiently well
controlled environment to determine a difference other than to keep
statistics of a large number of riders whose mileage is verifiably
known,
> Recently there was a post suggesting that wheels using butted spokes
> could be built to higher tension w/o spoke pull through. How does
> the nipple know what size spoke is pulling it?
Cyclic stress causes fatigue cracks and a thinner spoke as a lower
N/mm elongation than a fat one. Hence the rim knows as does the
nipple, that stress excursions with thinner spokes are lower, assuming
both rim and nipples are inhabited by Maxwell's demons making such
observations
> I recall that using a larger number of thinner spokes makes better
> wheels but not necessarily butted spokes.
If you believe that, then you must have given some thought to why that
should be true. If you have, then you know the answer to the second part.
Qui si parla Campagnolo
straight 14 ga vs butted 14/15 or is the difference theory.
have seen some wheels with 14g that seem to loosen spokes a lot(not my
build)...but can ya make a wheel reliable with 14g spokes-sure...
<< Recently there was a post suggesting that wheels using butted spokes
could be built to higher tension w/o spoke pull through.
tension is tension, regardless of spoke gauge...about 100 KGF is what you are
looking for.
Alex Rodriguez
wdu...@ucwphilly.rr.com says...
>
>
>I've always used 14 gauge straight gauge 36 spoke wheels on my touring bike
>because I was told that these spokes are more dependable under touring
>loads. Now it sounds like most posters here feel that double butted wheels
>are at least as strong or maybe stronger. My builder who is converting my
>bike to cassette and will be rebuilding my rear wheel, feels that I should
>go with double butted. I weigh a little under 180. Used to go up to 195,
>but no more. Since the front wheel doesn't need to be rebuilt, it will
>remain 14 gauge straight gauge 36 spoked wheel. What is the primary reason
>for double butted wheels? I would think weight savings. How much savings
>would that be?
Weight savings is an extra bonus. The real reason is that a wheel with
DB spokes will be more durable, not necessarily stronger.
Paul Kopit
On Mon, 10 Feb 2003 03:20:41 GMT, jobst....@stanfordalumni.org
wrote:
Wayne T
<jobst....@stanfordalumni.org> wrote in message
news:dUE1a.65300$Ik.27...@typhoon.sonic.net...
> Paul Kopit writes:
>
> > I'm agnostic. Has anyone really seen any difference in a wheel with
> > straight 14 ga vs butted 14/15 or is the difference theory.
>
> This would require a life test on a machine for both types of spoke,
> something the industry has not been doing since wire spoked wheels
> were first used. The use of strain bolts in industry in general has
> been shown to have major advantage, but then the machines themselves
> are the life test. Bicycle riders are not a sufficiently well
> controlled environment to determine a difference other than to keep
> statistics of a large number of riders whose mileage is verifiably
> known,
If I'm reading you right, it sounds like you are questioning the soundness
of those posts stating that 14/15 double butted spoked wheels are sturdier
than straight 14 gauge because there has not really been any scientific
tests showing it one way or the other.
Wayne T
"Sheldon Brown" <capt...@sheldonbrown.com> wrote in message
news:3E471AD...@sheldonbrown.com...
Paul Kopit wrote:
> I'm agnostic. Has anyone really seen any difference in a wheel with
> straight 14 ga vs butted 14/15 or is the difference theory.
>
> Recently there was a post suggesting that wheels using butted spokes
> could be built to higher tension w/o spoke pull through. How does the
> nipple know what size spoke is pulling it?
>
> I recall that using a larger number of thinner spokes makes better
> wheels but not necessarily butted spokes.
I was hard to convince, favored straight gauge for a long time, but
eventually I noticed a high correlation between rims cracking around the
spoke holes and the use of straight 2 mm spokes.
I must admit that I have never cracked a rim but have experienced spoke
breakage on my touring bike. Also, though I have had 14/15 double butted
spokes break, I have not experienced breakage with straight 14 gauge spokes.
Maybe it was just the luck of the draw or perhaps the 14 gauge DT spokes
were superior to the 14/15 gauge spokes which may not have been as good. In
fact I don't think they were of DT quality, so perhaps double butted DTs
would last longer. I guess the main point I am trying to make is that with
a touring wheel, the primary concern is with broken spokes, not cracked
rims, IMHO. At least that has been my experience.
Wayne T
"Alex Rodriguez" <ad...@columbia.edu> wrote in message
news:b28o4k$gt5$3...@newsmaster.cc.columbia.edu...
If the straight guage is stronger wouldn't it be more durable than double
butted under heavy loads?
lis...@earthlink.net
> > Weight savings is an extra bonus. The real reason is that a wheel with
> > DB spokes will be more durable, not necessarily stronger.
>
> If the straight guage is stronger wouldn't it be more durable than double
> butted under heavy loads?
No, because spokes don't break from overload, they break from fatigue.
Double butted, or swaged, spokes fatigue more slowly.
--
Ted Bennett
Portland OR
jobst....@stanfordalumni.org
>>> I've always used 14 gauge straight gauge 36 spoke wheels on my
>>> touring bike because I was told that these spokes are more
>>> dependable under touring loads. Now it sounds like most posters
>>> here feel that double butted wheels are at least as strong or
>>> maybe stronger. My builder who is converting my bike to cassette
>>> and will be rebuilding my rear wheel, feels that I should go with
>>> double butted. I weigh a little under 180. Used to go up to 195,
>>> but no more. Since the front wheel doesn't need to be rebuilt, it
>>> will remain 14 gauge straight gauge 36 spoked wheel. What is the
>>> primary reason for double butted wheels? I would think weight
>>> savings. How much savings would that be?
>> Weight savings is an extra bonus. The real reason is that a wheel
>> with DB spokes will be more durable, not necessarily stronger.
> If the straight gauge is stronger wouldn't it be more durable than
> double butted under heavy loads?
If... but they are not, because their ends, where they fail, are
identical for both types of spoke, having the same cross section. The
swaged spoke having been made from a straight gauge spoke blank.
Fatigue is a process by which a metal is torn apart by repeated
loading much lower than that needed to forcefully break the part.
Therefore, it is not rupture strength but rather stress levels under
cyclic loading that cause spokes to fail. That is why stress
relieving is highly important in building durable wheels.
Mark Hickey
Whoa there, Wayne... Get your attributions correct. You can't tell
who wrote what in your post, and your info is horribly intermingled
with that written by Sheldon Brown, which makes it read like a Robin
Williams on cocaine "conversation".
Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame
>"Sheldon Brown" <capt...@sheldonbrown.com> wrote in message
Mark Hickey
>If the straight guage is stronger wouldn't it be more durable than double
>butted under heavy loads?
Imagine using 500 pound test fishing line with two fishing rods.
One rod is made from a 1/2 inch thick carbon fiber hollow tube all the
way to the top.
The other is a "normal fishing pole", tapering from 1/2" at the base
to almost nothing at the tip..
"Riding" consists of getting the hook snagged on something solid and
whipping the pole back and forth trying to free it.
The thick rod is the straight 14g spoke, while the thin rod is the
butted spoke. It's pretty obvious the stresses on the pole at the
handle will be MUCH higher for the thick non-tapered rod, and it will
be much more likely to break as you pull. The stresses will be
distributed along the length of the thinner fishing rod and it won't
break, even though it's "not as strong" as that thick, non-tapered
rod.
Terry Morse
> The thick rod is the straight 14g spoke, while the thin rod is the
> butted spoke. It's pretty obvious the stresses on the pole at the
> handle will be MUCH higher for the thick non-tapered rod, and it will
> be much more likely to break as you pull. The stresses will be
> distributed along the length of the thinner fishing rod and it won't
> break, even though it's "not as strong" as that thick, non-tapered
> rod.
Cool analogy, but I don't think it works. I'll switch back to spokes:
Two properly built wheels, one with straight gauge and one with swaged
(butted) spokes, will have the same spoke tension. Regular readers of
rbt know that the maximum tension in a spoke is achieved when the wheel
is unused, and the tension only decreases at the contact area.
Therefore, the maximum stress experienced by the spoke heads (site of
most failures) is identical for both types of spokes.
The minimum spoke stress will be lower in the straight spokes, because
these spokes aren't as "springy". This might produce a shorter fatigue
life, because the material is experiencing a wider range of stresses. It
would be hard to know without testing.
--
terry morse Palo Alto, CA http://www.terrymorse.com/bike/
Sheldon Brown
>>The thick rod is the straight 14g spoke, while the thin rod is the
>>butted spoke. It's pretty obvious the stresses on the pole at the
>>handle will be MUCH higher for the thick non-tapered rod, and it will
>>be much more likely to break as you pull. The stresses will be
>>distributed along the length of the thinner fishing rod and it won't
>>break, even though it's "not as strong" as that thick, non-tapered
>>rod.
Terry Morse demurred:
> Cool analogy, but I don't think it works. I'll switch back to spokes:
>
> Two properly built wheels, one with straight gauge and one with swaged
> (butted) spokes, will have the same spoke tension. Regular readers of
> rbt know that the maximum tension in a spoke is achieved when the wheel
> is unused, and the tension only decreases at the contact area.
> Therefore, the maximum stress experienced by the spoke heads (site of
> most failures) is identical for both types of spokes.
That's true for smooth riding, but not correct when impact loads are
considered.
In-line impact loads tend to push the rim inward at the point of impact.
This causes a tendency for the rim to bulge outward in areas
immediately adjacent to the impact point. The spokes in the bulge zones
do suffer transient increases in stress.
Lateral stresses also can result in locally increased spoke tension.
Sheldon "Double Bubble" Brown
+--------------------------------------------------+
| Conscience is the inner voice which warns us |
| that someone might be looking. |
| --H.L. Mencken |
+--------------------------------------------------+
Paul Kopit
make? Well built wheels don't break spokes unless chains get launched
into them, big holes/bumps, or accidents. Tensioned properly, spokes
don't pull through the rim. Very large numbers of excellent wheels
have been built with straight guage spokes.
If the spoke makers don't bother to measure, they can say anything
they like. I would think that if there were significant differences
they would measure.
On Tue, 11 Feb 2003 02:07:59 GMT, "Wayne T" <wdu...@ucwphilly.rr.com>
wrote:
jobst....@stanfordalumni.org
> Two properly built wheels, one with straight gauge and one with
> swaged (butted) spokes, will have the same spoke tension. Regular
> readers of rbt know that the maximum tension in a spoke is achieved
> when the wheel is unused, and the tension only decreases at the
> contact area. Therefore, the maximum stress experienced by the
> spoke heads (site of most failures) is identical for both types of
> spokes.
> The minimum spoke stress will be lower in the straight spokes,
> because these spokes aren't as "springy". This might produce a
> shorter fatigue life, because the material is experiencing a wider
> range of stresses. It would be hard to know without testing.
Since spoke failure is a fatigue phenomenon caused by cycle stress,
there is no testing required to determine whether this alters fatigue
life. It is as basic a materials problem as there is. With both
spokes at the same peak stress and one with a larger cyclic stress
excursion than the other will statistically fail sooner, assuming
there will be a failure.
The same goes for a rim under the choice of the two spokes.
Terry Morse
> Terry Morse demurred:
>
> > Two properly built wheels, one with straight gauge and one with swaged
> > (butted) spokes, will have the same spoke tension. Regular readers of
> > rbt know that the maximum tension in a spoke is achieved when the wheel
> > is unused, and the tension only decreases at the contact area.
> > Therefore, the maximum stress experienced by the spoke heads (site of
> > most failures) is identical for both types of spokes.
>
> That's true for smooth riding, but not correct when impact loads are
> considered.
>
> In-line impact loads tend to push the rim inward at the point of impact.
> This causes a tendency for the rim to bulge outward in areas
> immediately adjacent to the impact point. The spokes in the bulge zones
> do suffer transient increases in stress.
I don't see the diffence between smooth loading and in-line impact
loading. There's not much mass in the rim, so the reaction of the
rim/spoke system ought to be similar in both cases.
Terry Morse
> Since spoke failure is a fatigue phenomenon caused by cycle stress,
> there is no testing required to determine whether this alters fatigue
> life. It is as basic a materials problem as there is. With both
> spokes at the same peak stress and one with a larger cyclic stress
> excursion than the other will statistically fail sooner, assuming
> there will be a failure.
Do you have a reference to demonstrate the "larger cyclic stress"
behavior? The material fatigue tests I remember lowered the stress down
to zero on every cycle.
jobst....@stanfordalumni.org
>> That's true for smooth riding, but not correct when impact loads
>> are considered.
>> In-line impact loads tend to push the rim inward at the point of
>> impact. This causes a tendency for the rim to bulge outward in
>> areas immediately adjacent to the impact point. The spokes in the
>> bulge zones do suffer transient increases in stress.
> I don't see the difference between smooth loading and in-line impact
> loading. There's not much mass in the rim, so the reaction of the
> rim/spoke system ought to be similar in both cases.
That is correct. There is no dynamic here, the response of the wheel
being so fast that its deflection is the same as static. The
magnitude of the outward bulge adjacent to the inward deflected rim
section is so small that the general statement that spoke tension is
greatest on an unloaded wheel is true for practical purposes.
jobst....@stanfordalumni.org
>> Since spoke failure is a fatigue phenomenon caused by cycle stress,
>> there is no testing required to determine whether this alters
>> fatigue life. It is as basic a materials problem as there is.
>> With both spokes at the same peak stress and one with a larger
>> cyclic stress excursion than the other will statistically fail
>> sooner, assuming there will be a failure.
> Do you have a reference to demonstrate the "larger cyclic stress"
> behavior? The material fatigue tests I remember lowered the stress
> down to zero on every cycle.
Some materials suffer more from stress reversals but steel is
interested in the stress change and the peak stress. I show a simple
diagram in "the Bicycle Wheel" what these effects are. See also:
http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
http://www.grc.nasa.gov/WWW/RT1996/5000/5220l.htm
Mark Hickey
> Mark Hickey wrote:
>
>> The thick rod is the straight 14g spoke, while the thin rod is the
>> butted spoke. It's pretty obvious the stresses on the pole at the
>> handle will be MUCH higher for the thick non-tapered rod, and it will
>> be much more likely to break as you pull. The stresses will be
>> distributed along the length of the thinner fishing rod and it won't
>> break, even though it's "not as strong" as that thick, non-tapered
>> rod.
>
>Cool analogy, but I don't think it works.
I think it gets to the heart of the matter. What I probably didn't
make clear enough is that the expected "breaking point" for either the
thick, non-tapered stiff pole and the tapered pole would be at the
point where the carbon fiber fishing pole joined the handle. Imagine
whip-sawing the pole back and forth and it's easy to see that the
stresses are distributed along the tapered pole, but concentrated at
the handle-pole junction of the straight fishing rod.
As you said, the point of maximum and minimum tension are reversed,
but that doesn't really change the model in terms of distributing the
changes in stress vs. concentrating it at the handle (or elbow or
thread).
Mike DeMicco
> What I'm questioning is how much difference, if any, does it really
> make? Well built wheels don't break spokes unless chains get launched
> into them, big holes/bumps, or accidents. Tensioned properly, spokes
> don't pull through the rim. Very large numbers of excellent wheels have
> been built with straight guage spokes.
I'm with you. I think the difference is in the noise level. I've had
butted spokes break as well as straight gage. In the absence of test data,
I'll save a bit of money and make wheel building a little easier by using
straight gage.
Wayne T
<jobst....@stanfordalumni.org> wrote in message
news:GX_1a.65503$Ik.27...@typhoon.sonic.net...
so, essentially what you are saying is that the fact that the middle of a
double butted spoke is thinner, it allows it to flex and take the stress off
the ends of the spoke where most spoke tend to break. But wouldn't the fact
that the middle of a double butted spoke flexes more than a straight gauge,
cause the middle section to fatique more and, therefore, cause more mid
section breakage?
Wayne T
<lis...@earthlink.net> wrote in message
news:lisated-9F013A...@news.mindspring.com...
I guess it is hard for me to understand how something thinner could fatigue
faster than something thicker.
Wayne T
"Mark Hickey" <ma...@habcycles.com> wrote in message
news:fo2i4v8o635d9i7gq...@4ax.com...
Interesting analogy. It makes sense. Thanks.
Wayne T
> Mark Hickey wrote:
>
> >>The thick rod is the straight 14g spoke, while the thin rod is the
> >>butted spoke. It's pretty obvious the stresses on the pole at the
> >>handle will be MUCH higher for the thick non-tapered rod, and it will
> >>be much more likely to break as you pull. The stresses will be
> >>distributed along the length of the thinner fishing rod and it won't
> >>break, even though it's "not as strong" as that thick, non-tapered
> >>rod.
>
> Terry Morse demurred:
>
> > Cool analogy, but I don't think it works. I'll switch back to spokes:
> >
> > Two properly built wheels, one with straight gauge and one with swaged
> > (butted) spokes, will have the same spoke tension. Regular readers of
> > rbt know that the maximum tension in a spoke is achieved when the wheel
> > is unused, and the tension only decreases at the contact area.
> > Therefore, the maximum stress experienced by the spoke heads (site of
> > most failures) is identical for both types of spokes.
>
> That's true for smooth riding, but not correct when impact loads are
> considered.
>
> In-line impact loads tend to push the rim inward at the point of impact.
> This causes a tendency for the rim to bulge outward in areas
> immediately adjacent to the impact point. The spokes in the bulge zones
> do suffer transient increases in stress.
So which would handle this stress better? 14 straight gauge or double
butted?
Wayne T
"Paul Kopit" <p.k...@verizon.net> wrote in message
news:dmfi4vcuik9bp1cku...@4ax.com...
> What I'm questioning is how much difference, if any, does it really
> make? Well built wheels don't break spokes unless chains get launched
> into them, big holes/bumps, or accidents.
The question then is when you hit a big hole or bump under heavy load, which
would hold up better? 14 straight gauge or 14/15 double butted? I know of
a 250 pounder that kept breaking 14 gauge spokes. He had to go to a 12
gauge.
\
A Muzi
"Wayne T" <wdu...@ucwphilly.rr.com> wrote in message
news:Q1k2a.21890$KM2.3...@twister.southeast.rr.com...
> so, essentially what you are saying is that the fact that the middle of a
> double butted spoke is thinner, it allows it to flex and take the stress
off
> the ends of the spoke where most spoke tend to break. But wouldn't the
fact
> that the middle of a double butted spoke flexes more than a straight
gauge,
> cause the middle section to fatique more and, therefore, cause more mid
> section breakage?
> >
> > Jobst Brandt
> > jobst....@stanfordalumni.org
> > Palo Alto CA
>
>
Spokes almost never break anywhere but the head.
"Midsection breakage" is all but unknown.
--
Andrew Muzi
http://www.yellowjersey.org
Open every day since 1 April 1971
lis...@earthlink.net
> > > If the straight guage is stronger wouldn't it be more durable than
> double
> > > butted under heavy loads?
> >
> >
> > No, because spokes don't break from overload, they break from fatigue.
> > Double butted, or swaged, spokes fatigue more slowly.
>
>
> I guess it is hard for me to understand how something thinner could fatigue
> faster than something thicker.
It is true that thinner metal, given equal stress cycles, will break
sooner than thicker metal. But in the case of spokes, as A. Muzi and
others have pointed out, spokes almost always break at the head, where
the metal is the same thickness for swaged or for straight gauge spokes.
Fatiguing of the thinner portion of the spoke isn't the problem. The
thinner portion of the spoke helps to reduce the stress cycle on the
head and elbow.
Sergio SERVADIO
Suppose you have a bad back that gets sore when riding over rough terrain.
Don't you profit by not sitting hard on the saddle and prefer instead to
absorb shocks with your knees and legs?
The comparison goes only as far as your knees don't fatigue.
As if it were ... .
Sergio
Pisa
Terry Morse
> Some materials suffer more from stress reversals but steel is
> interested in the stress change and the peak stress. I show a simple
> diagram in "the Bicycle Wheel" what these effects are. See also:
>
> http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
> http://www.grc.nasa.gov/WWW/RT1996/5000/5220l.htm
Nice references, thanks.
jobst....@stanfordalumni.org
>>>> Weight savings is an extra bonus. The real reason is that a
>>>> wheel with DB spokes will be more durable, not necessarily
>>>> stronger.
>>> If the straight gauge is stronger wouldn't it be more durable than
>>> double butted under heavy loads?
>> If... but they are not, because their ends, where they fail, are
>> identical for both types of spoke, having the same cross section.
>> The swaged spoke having been made from a straight gauge spoke
>> blank.
>> Fatigue is a process by which a metal is torn apart by repeated
>> loading much lower than that needed to forcefully break the part.
>> Therefore, it is not rupture strength but rather stress levels
>> under cyclic loading that cause spokes to fail. That is why stress
>> relieving is highly important in building durable wheels.
> So, essentially what you are saying is that the fact that the middle
> of a double butted spoke is thinner, it allows it to flex and take
> the stress off the ends of the spoke where most spoke tend to break.
> But wouldn't the fact that the middle of a double butted spoke
> flexes more than a straight gauge, cause the middle section to
> fatigue more and, therefore, cause more mid section breakage?
No. That spokes do not break in their slender mid sections is well
established. Failure occurs at stress concentrating features where
the spoke is not uniformly loaded and where it has corners in which
stresses are naturally higher. An analogy would be a uniformly wide
hallway that makes a right angle turn with a stream of people walking
in the same direction. Congestion at the corner is inevitable as is
stress concentration in a spoke's threads, elbow, and head.
To visualize an extreme example, cut 10cm from the middle of a spoke
and replace it with a coil spring with a stiffness of 200lbs/inch of
stretch. Instead of tightening the spoke by turning the spoke nipple,
stretch the spring an inch and attach it to hooks on the cut ends of
the spoke. This tensions the spoke to 200lbs. Deflecting that spoke
under the usual loads (causing a length change of 0.003-0.005") would
cause less than 1lb change in spoke load instead of 50lbs or more.
By adding elasticity, swaging spokes emulates that function.
ajames54
wrote:
SNIP
>
>No. That spokes do not break in their slender mid sections is well
>established. Failure occurs at stress concentrating features where
>the spoke is not uniformly loaded and where it has corners in which
>stresses are naturally higher.
SNIP
>
>Jobst Brandt
>jobst....@stanfordalumni.org
>Palo Alto CA
Kind of a question kind of a statement... Would not the extra
cold working of the spoke in forging the head and then bending
the spoke also be a factor in why spokes break at the head?
jobst....@stanfordalumni.org
>> No. That spokes do not break in their slender mid sections is well
>> established. Failure occurs at stress concentrating features where
>> the spoke is not uniformly loaded and where it has corners in which
>> stresses are naturally higher.
> Kind of a question kind of a statement... Would not the extra cold
> working of the spoke in forging the head and then bending the spoke
> also be a factor in why spokes break at the head?
No. DT has the spoke wire delivered cold worked to its maximum
strength. Further cold working does not increase tensile strength.
This is one of the features of DT spoke material. It has the highest
yield strength of spokes I tested yet it has the greatest ductility.
As I have often pointed out, stress relieving is essential to durable
wheels. The stresses that are relieved by this process are ones
remaining from spoke forming as well as ones introduces during wheel
building. There is a whole book on this subject.
http://www.avocet.com/wheelbook/wheelbook.html
ajames54
wrote:
>A? James writes:
>
>>> No. That spokes do not break in their slender mid sections is well
>>> established. Failure occurs at stress concentrating features where
>>> the spoke is not uniformly loaded and where it has corners in which
>>> stresses are naturally higher.
>
>> Kind of a question kind of a statement... Would not the extra cold
>> working of the spoke in forging the head and then bending the spoke
>> also be a factor in why spokes break at the head?
>
>No. DT has the spoke wire delivered cold worked to its maximum
>strength. Further cold working does not increase tensile strength.
>This is one of the features of DT spoke material. It has the highest
>yield strength of spokes I tested yet it has the greatest ductility.
I was thinking more along the lines of Cold Work Embrittlement ..
years ago I did some microsections on spokes (an admittedly small
sample) and the grain structure showed a significant amount of
cold work in those areas.
But since I have no idea what alloys they use or what specs they
buy them to I will defer ..
Tom Nakashima
Did you translate this yourself? And have you got any response from the
Deutschland who have used your book to build a wheel?
-tom
<jobst....@stanfordalumni.org> wrote in message
news:Omv2a.65826$Ik.27...@typhoon.sonic.net...
jobst....@stanfordalumni.org
>>>> No. That spokes do not break in their slender mid sections is
>>>> well established. Failure occurs at stress concentrating
>>>> features where the spoke is not uniformly loaded and where it has
>>>> corners in which stresses are naturally higher.
>>> Kind of a question kind of a statement... Would not the extra cold
>>> working of the spoke in forging the head and then bending the
>>> spoke also be a factor in why spokes break at the head?
>> No. DT has the spoke wire delivered cold worked to its maximum
>> strength. Further cold working does not increase tensile strength.
>> This is one of the features of DT spoke material. It has the
>> highest yield strength of spokes I tested yet it has the greatest
>> ductility.
> I was thinking more along the lines of Cold Work Embrittlement ...
> years ago I did some microsections on spokes (an admittedly small
> sample) and the grain structure showed a significant amount of cold
> work in those areas.
As I said, their steel is the most ductile and that's what makes it so
robust. Swaging the midsections is trivial compared to rolling
threads and forming heads.
> But since I have no idea what alloys they use or what specs they
> buy them to I will defer.
So even if you knew the alloys, what would that do to your assessment
and comments you might be holding back?
Sheldon Brown
>>Some materials suffer more from stress reversals but steel is
>>interested in the stress change and the peak stress. I show a simple
>>diagram in "the Bicycle Wheel" what these effects are. See also:
>>
>>http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
>>http://www.grc.nasa.gov/WWW/RT1996/5000/5220l.htm
In the second of these references, I found:
"In monolithic materials, it has been observed that tensile mean
stresses are detrimental and compressive mean stresses are beneficial to
fatigue life in comparison to a base of zero mean stress."
There has been some controversy on this list about the observed greater
durability of quick release axles vis-a-vis solid axles, and this would
seem to support those of us who maintain that QR axles are less prone to
breakage than solid ones, despite having less material.
Sheldon "Vindicated By NASA" Brown
+--------------------------------------------------+
| Cynic: A blackguard whose faulty vision sees |
| things as they are, not as they ought to be. |
| --Ambrose Bierce |
jobst....@stanfordalumni.org
http://www.avocet.com/wheelbook/wheelbook.html
> Interesting to see a German Language Edition of the Bicycle Wheel.
> Did you translate this yourself? And have you got any response from
> the Deutschland who have used your book to build a wheel?
It got a good reception back when Avocet still had a distributor in
Germany but that has reduced to a trickle of sales, even though
Amazon.de lists it.
I wrote the translation but had a bikie friend in Germany look after
the syntax and grammar. It is written in the same style as the
English in which I try to live up to Richard Feynman's axiom:
"If you can't explain it in plain English, then you probably don't
understand it yourself."
jobst....@stanfordalumni.org
>>> Some materials suffer more from stress reversals but steel is
>>> interested in the stress change and the peak stress. I show a
>>> simple diagram in "the Bicycle Wheel" what these effects are. See
>>> also:
http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
http://www.grc.nasa.gov/WWW/RT1996/5000/5220l.htm
> In the second of these references, I found:
> "In monolithic materials, it has been observed that tensile mean
> stresses are detrimental and compressive mean stresses are
> beneficial to fatigue life in comparison to a base of zero mean
> stress."
> There has been some controversy on this list about the observed
> greater durability of quick release axles vis-a-vis solid axles, and
> this would seem to support those of us who maintain that QR axles
> are less prone to breakage than solid ones, despite having less
> material.
That doesn't apply to axle steel and the difference between QR axles
and solid ones is structurally minimal, the material (bore) lying in
the neutral axis. I am fairly sure that the QR axles are better
material. My rear axle failures resulted from horizontal slot
dropouts which give no fore and aft bending support to the axle.
"Vertical" dropouts support the forward circumference of the jam nut
and therefore, support most of the bending load from chain tension,
the one that generally causes fatigue failures. That is why these
dropouts occasionally fail on the right* side.
* = 'drive side'
Paul Kopit
Wheelsmith spokes taper more abruptly than the DTs.
What is the purpose of making the spoke thicker again at the nipple
end?
Sheldon Brown
>>>>Some materials suffer more from stress reversals but steel is
>>>>interested in the stress change and the peak stress. I show a
>>>>simple diagram in "the Bicycle Wheel" what these effects are. See
>>>>also:
>>>
>
> http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
> http://www.grc.nasa.gov/WWW/RT1996/5000/5220l.htm
I responded:
>>In the second of these references, I found:
>
>
>>"In monolithic materials, it has been observed that tensile mean
>>stresses are detrimental and compressive mean stresses are
>>beneficial to fatigue life in comparison to a base of zero mean
>>stress."
>
>
>>There has been some controversy on this list about the observed
>>greater durability of quick release axles vis-a-vis solid axles, and
>>this would seem to support those of us who maintain that QR axles
>>are less prone to breakage than solid ones, despite having less
>>material.
Jobst answered in part:
> That doesn't apply to axle steel
Why not?
Sheldon "Curious" Brown
+------------------------------------------+
| So we'll go no more a roving |
| So late into the night, |
| Though the heart be still as loving, |
| And the moon be still as bright. |
| |
| For the sword outwears its sheath, |
| And the soul wears out the breast, |
| And the heart must pause to breathe, |
| And Love itself have rest. |
| |
| Though the night was made for loving, |
| And the day returns too soon, |
| Yet we'll go no more a roving |
| By the light of the moon. |
| --Lord Byron |
+------------------------------------------+
dan baker
> There has been some controversy on this list about the observed greater
> durability of quick release axles vis-a-vis solid axles, and this would
> seem to support those of us who maintain that QR axles are less prone to
> breakage than solid ones, despite having less material.
gee, I hate to get caught between a rock and a hard pace with you two,
but its a pretty well-known fact that tubes are better than solid rods
for bending moment stress. which an axle should be if it is properly
tight. Now, if its loose, and in pure shear, then its a different
story. the arguement might be clouded if one considers whether its
more likely a person would apply proper tension to a QR skewer versus
a bolt-on nut.
d
Wayne T
"A Muzi" <a...@yellowjersey.org> wrote in message
news:v4jnd21...@corp.supernews.com...
Now if I could only remember where my breakage occurred. Its been a while
since I've had a broken spoke.
Wayne T
<lis...@earthlink.net> wrote in message
news:lisated-A2B6D8...@news.mindspring.com...
Thanks. That answers my question. Very interesting.
jobst....@stanfordalumni.org
> Would the manner that the spokes were swaged make any difference?
> The Wheelsmith spokes taper more abruptly than the DT's.
The two spokes are swaged by a different process but the effect is the
same as far as stress is concerned.
You'll notice that the transition is a smooth radius where the taper
ends on the reduced diameter. This is the transition that counts, the
other can be a sharp promontory and make no difference. If you view
this as a pipe with a liquid (stress) flowing through it, it will
become obvious where flow lines will concentrate and rush around
corners. This is the way FEA displays are qualitatively displayed.
You can see a similar effect on a wind chart.
http://sfports.wr.usgs.gov/wind/streaklines.shtml
Where velocity is high, the vectors are also closer together.
> What is the purpose of making the spoke thicker again at the nipple
> end?
Threads are relatively sharp cornered features and are a typical area
where spokes break. Therefore, having a bit of greater cross section
reduces stress.
jobst....@stanfordalumni.org
>>>> Some materials suffer more from stress reversals but steel is
>>>> interested in the stress change and the peak stress. I show a
>>>> simple diagram in "the Bicycle Wheel" what these effects are.
>>>> See also:
http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
http://www.grc.nasa.gov/WWW/RT1996/5000/5220l.htm
>>> In the second of these references, I found:
>>> "In monolithic materials, it has been observed that tensile mean
>>> stresses are detrimental and compressive mean stresses are
>>> beneficial to fatigue life in comparison to a base of zero mean
>>> stress."
>>> There has been some controversy on this list about the observed
>>> greater durability of quick release axles vis-a-vis solid axles, and
>>> this would seem to support those of us who maintain that QR axles
>>> are less prone to breakage than solid ones, despite having less
>>> material.
>> That doesn't apply to axle steel
> Why not?
These monolithic materials are typically ceramics and other non ductile
composites.
http://www.grc.nasa.gov/WWW/RT1997/5000/5920janosik.htm
http://www.uni-bayreuth.de/forschungsberichte/94/pen95012231.html
By Poisson's ratio, that characteristic of a material bulging
laterally when compressed axially, makes compression stress into
tensile stress in the orthogonal axes. Therefore, if the material is
elastic, its compressive load also causes transverse tension. By this
mechanism, compression also pulls a material apart but not in the axis
of loading.
Cork, a marvelous natural material, has a Poisson's ratio of zero and
does not extrude out of a gasket gap when compressed, nor does it
become double its length when pressed into a Champaign bottle as a
rubber stopper would with such a reduction in diameter.
http://silver.neep.wisc.edu/~lakes/PoissonIntro.html
jobst....@stanfordalumni.org
>> There has been some controversy on this list about the observed
>> greater durability of quick release axles vis-a-vis solid axles,
>> and this would seem to support those of us who maintain that QR
>> axles are less prone to breakage than solid ones, despite having
>> less material.
> gee, I hate to get caught between a rock and a hard pace with you
> two, but its a pretty well-known fact that tubes are better than
> solid rods for bending moment stress. which an axle should be if it
> is properly tight. Now, if its loose, and in pure shear, then its a
> different story. the argument might be clouded if one considers
> whether its more likely a person would apply proper tension to a QR
> skewer versus a bolt-on nut.
That is not true. The hole in the center does not make the shaft more
durable or less fatigue resistant, although the core of the shaft adds
practically nothing to torsional or bending strength. It is just
there. Whether hollow axles are made of better material may be another
parameter to consider but good track axles are at least as durable as
QR axles of the same OD.
QR compression increases compressive stress while the magnitude of
stress cycles from road shock and chain tension remain unchanged.
Sheldon Brown
This is interesting in theory, but when axles break, they break
perpendicular to the axis.
It seems to me that the issue of ductility isn't germane if the material
isn't compressed to the yield point.
Sheldon "A Mechanic, Not An Engineer" Brown
+---------------------------------------------------+
| There was a man with a tongue of wood |
| Who essayed to sing. |
| And in truth it was lamentable. |
| But there was one who heard |
| The clip-clapper of this tongue of wood |
| And knew what the man wished to sing, |
| And with that the singer was content. |
| --Stephen Crane |
+---------------------------------------------------+
ajames54
wrote:
>A? James writes:
>
>As I said, their steel is the most ductile and that's what makes it so
>robust. Swaging the midsections is trivial compared to rolling
>threads and forming heads.
>
>> But since I have no idea what alloys they use or what specs they
>> buy them to I will defer.
>
>So even if you knew the alloys, what would that do to your assessment
>and comments you might be holding back?
>
It isn't so much holding back as simply not wanting to
comment on something if I'm not sure ... different steels work
harden differently , Since Austenitic steel gets a great deal of
strength from work hardening, doesn't require heat treatment (at
least not to make it harder), has very low magnetic permeability
and is generally pretty resistant to Cold Work Embrittlement I
would normally have assumed that Stainless Spokes probably were
made from one of the common Austenitic grades, like 302 or 316
...
Even assuming that they are Austenitic steel different
grades have different properties... higher levels of Nitrogen
would make CWE more likely and higher levels of Nickel would
mitigate against it...though the higher Nickel material would
also be much more expensive.
As I said though it is just conjecture on my part (it is
also splitting a damn fine hair)... So even assuming it is
something like 302 and delivered to the plant fully annealed
there are so many other factors that it is almost impossible to
draw any firm conclusions from a description...
Give me a few fresh samples, an electron Microscope and
someone to run it then I'll venture an opinion, until then like I
say I'm just wondering...
jobst....@stanfordalumni.org
>>>> That doesn't apply to axle steel
>>> Why not?
>> These monolithic materials are typically ceramics and other non
>> ductile composites.
>> http://www.grc.nasa.gov/WWW/RT1997/5000/5920janosik.htm
>> http://www.uni-bayreuth.de/forschungsberichte/94/pen95012231.html
>> By Poisson's ratio, that characteristic of a material bulging
>> laterally when compressed axially, makes compression stress into
>> tensile stress in the orthogonal axes. Therefore, if the material
>> is elastic, its compressive load also causes transverse tension.
>> By this mechanism, compression also pulls a material apart but not
>> in the axis of loading.
> This is interesting in theory, but when axles break, they break
> perpendicular to the axis.
> It seems to me that the issue of ductility isn't germane if the
> material isn't compressed to the yield point.
If you consider the material in 3D, this separation of crystallites in
any direction upsets the strength of the material in more than one
plane. Stress reversal (compression / tension) has a significant
effect on fatigue life. Some materials more so than others.
http://www.mech.uwa.edu.au/DANotes/SSS/shafts/shafts.html
This second site shows a classic stress reversal application, that of
a rotation spindle that experiences a full stress reversal with every
revolution.
Sheldon Brown
jobst....@stanfordalumni.org wrote:
> Sheldon Brown writes:
>
>
>>>>>That doesn't apply to axle steel
>>>>
>
>>>>Why not?
>>>
>
>>>These monolithic materials are typically ceramics and other non
>>>ductile composites.
>>
>
>>>http://www.grc.nasa.gov/WWW/RT1997/5000/5920janosik.htm
>>>http://www.uni-bayreuth.de/forschungsberichte/94/pen95012231.html
>>
>
>>>By Poisson's ratio, that characteristic of a material bulging
>>>laterally when compressed axially, makes compression stress into
>>>tensile stress in the orthogonal axes. Therefore, if the material
>>>is elastic, its compressive load also causes transverse tension.
>>>By this mechanism, compression also pulls a material apart but not
>>>in the axis of loading.
>>
>
>>This is interesting in theory, but when axles break, they break
>>perpendicular to the axis.
>
>
>>It seems to me that the issue of ductility isn't germane if the
>>material isn't compressed to the yield point.
>
>
> If you consider the material in 3D, this separation of crystallites in
> any direction upsets the strength of the material in more than one
> plane.
Does this separation occur below the yield point?
> Stress reversal (compression / tension) has a significant
> effect on fatigue life. Some materials more so than others.
>
> http://www.industrialheating.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2832,8035,00.html
That citation includes the following:
"surface compressive residual stress will improve the fatigue resistance
since the applied stress and residual stress are additive. In contrast,
tensile residual stresses are detrimental to fatigue resistance..."
While I understand they're talking about residual stress, it isn't clear
to me that applied compressive stress would be any less beneficial, as
the NASA citation above stated.
> http://www.mech.uwa.edu.au/DANotes/SSS/shafts/shafts.html
>
> This second site shows a classic stress reversal application, that of
> a rotation spindle that experiences a full stress reversal with every
> revolution.
How is that germane to bicycle axles, which do not revolve? There is no
discussion here of an applied compressive load, only of the compressive
components of bending loads.
Sheldon "Still Believes QR Axles Are Less Failure Prone" Brown
+---------------------------------------------------------+
| I don't like spinach, and I'm glad I don't, because |
| if I liked it I'd eat it, and I just hate it. |
| --Clarence Darrow |
+---------------------------------------------------------+
jobst....@stanfordalumni.org
>> If you consider the material in 3D, this separation of crystallites
>> in any direction upsets the strength of the material in more than
>> one plane.
> Does this separation occur below the yield point?
Yes. Internal friction in a material is the stretching and breaking
of bonds. The "harder" the material the less internal losses and
distortions. This gets into the "dynamic" modulus of elasticity in
contrast to the usual modulus of elasticity, but then we've been there
a few times.
http://www.tiniusolsen.com/tmech2.html
>> Stress reversal (compression / tension) has a significant effect on
>> fatigue life. Some materials more so than others.
> That citation includes the following:
> "surface compressive residual stress will improve the fatigue
> resistance since the applied stress and residual stress are
> additive. In contrast, tensile residual stresses are detrimental to
> fatigue resistance..."
> While I understand they're talking about residual stress, it isn't
> clear to me that applied compressive stress would be any less
> beneficial, as the NASA citation above stated.
>> http://www.mech.uwa.edu.au/DANotes/SSS/shafts/shafts.html
>> This second site shows a classic stress reversal application, that
>> of a rotation spindle that experiences a full stress reversal with
>> every revolution.
> How is that germane to bicycle axles, which do not revolve? There
> is no discussion here of an applied compressive load, only of the
> compressive components of bending loads.
Unloaded, the QR axle is in compression, with chain load and some road
shock, depending on how tightly the QR is stressed, the axle deflects
into tension and then back into compression. This is a stress
reversal. The example of the rotating axle only makes the concept
clearer. I assumed it "an exercise for the reader" to see the
parallel between that and a rear QR axle on a bicycle.
Sheldon Brown
http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
http://www.grc.nasa.gov/WWW/RT1996/5000/5220l.htm
I observed:
>In the second of these references, I found:
> "In monolithic materials, it has been observed that tensile mean
> stresses are detrimental and compressive mean stresses are
> beneficial to fatigue life in comparison to a base of zero mean
> stress."
> There has been some controversy on this list about the observed
> greater durability of quick release axles vis-a-vis solid axles, and
> this would seem to support those of us who maintain that QR axles
> are less prone to breakage than solid ones, despite having less
> material.
Jobst asserted:
>That doesn't apply to axle steel and the difference between QR axles
>and solid ones is structurally minimal, the material (bore) lying in
>the neutral axis. I am fairly sure that the QR axles are better
>material. My rear axle failures resulted from horizontal slot
>dropouts which give no fore and aft bending support to the axle.
>"Vertical" dropouts support the forward circumference of the jam nut
>and therefore, support most of the bending load from chain tension,
>the one that generally causes fatigue failures. That is why these
>dropouts occasionally fail on the right* side.
There has been a lot of verbiage spilt since then and lots of arcane
references, but none of them has explained what property makes "axle
steel" not subject to the same physical laws that govern other
"monolithic materials."
I remain unconvinced that the NASA quote doesn't apply, and indeed
explain the observed greater reliability of quick-release axles.
Jobst:
> Unloaded, the QR axle is in compression, with chain load and some road
> shock, depending on how tightly the QR is stressed, the axle deflects
> into tension and then back into compression. This is a stress
> reversal.
certainly there is occasional tension on parts of a quick-release axle,
but the greatly predominant mode is compression, as is evidenced by the
many riders who've ridden long distances on broke QR axles held together
by their skewers, and only noticed the break after removing the wheel
for some reason.
The compression of the skewer creates a bias that prevents the axle from
experiencing any tensile load except at times of unusual stress, as when
hitting a pothole. Even when this happens, the magnitude of the tensile
stress is greatly decreased by the countervailing compressive force from
the skewer. Since it is clearly the tensile forces that cause the axle
to break, I find the NASA hypothesis quite convincing.
Sheldon "Sometimes NASA Is Right" Brown
Newtonville, Massachusetts
+--------------------------------------+
| Truth, like a torch, |
| the more it's shook it shines. |
| --Sir Wm. Hamilton |
+--------------------------------------+
jobst....@stanfordalumni.org
http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
http://www.grc.nasa.gov/WWW/RT1996/5000/5220l.htm
>>> In the second of these references, I found:
>>> "In monolithic materials, it has been observed that tensile mean
>>> stresses are detrimental and compressive mean stresses are
>>> beneficial to fatigue life in comparison to a base of zero mean
>>> stress."
>>> There has been some controversy on this list about the observed
>>> greater durability of quick release axles vis-a-vis solid axles, and
>>> this would seem to support those of us who maintain that QR axles
>>> are less prone to breakage than solid ones, despite having less
>>> material.
>> That doesn't apply to axle steel and the difference between QR
>> axles and solid ones is structurally minimal, the material (bore)
>> lying in the neutral axis. I am fairly sure that the QR axles are
>> better material. My rear axle failures resulted from horizontal
>> slot dropouts which give no fore and aft bending support to the
>> axle. "Vertical" dropouts support the forward circumference of the
>> jam nut and therefore, support most of the bending load from chain
>> tension, the one that generally causes fatigue failures. That is
>> why these dropouts occasionally fail on the right* side.
> There has been a lot of verbiage spilt since then and lots of arcane
> references, but none of them has explained what property makes "axle
> steel" not subject to the same physical laws that govern other
> "monolithic materials."
> I remain unconvinced that the NASA quote doesn't apply, and indeed
> explain the observed greater reliability of quick-release axles.
The QR rear axle operates like the rotating wheel axle in the example
given earlier. That is, although it has a relatively light
compression it has large tension caused mainly by chain pull.
Considering that a crank is about 170mm and a chainwheel is about
100mm radius, then a 160lb rider outs a 270lb chain force on the axle
to which at least half the rider weight bears on the rear axle
vertically. When (not) supported by a horizontal dropout slot, this
is a large bending load to which the QR tension adds practically
nothing. The bending load causes about 500lbs tension and compression
in the forward and trailing part of the axle, the ball bearing being
about an inch away from the face of the jam nut and having a diameter
of somewhat less than 0.2".
>>> Unloaded, the QR axle is in compression, with chain load and some
>>> road shock, depending on how tightly the QR is stressed, the axle
>>> deflects into tension and then back into compression. This is a
>>> stress reversal.
> Certainly there is occasional tension on parts of a quick-release axle,
> but the greatly predominant mode is compression, as is evidenced by the
> many riders who've ridden long distances on broke QR axles held together
> by their skewers, and only noticed the break after removing the wheel
> for some reason.
The compression from the QR is piffles compared to the dynamic bending
loads the axle supports. I think the stresses caused by bending are
grossly underestimated by most observers.
> The compression of the skewer creates a bias that prevents the axle
> from experiencing any tensile load except at times of unusual
> stress, as when hitting a pothole. Even when this happens, the
> magnitude of the tensile stress is greatly decreased by the
> countervailing compressive force from the skewer. Since it is
> clearly the tensile forces that cause the axle to break, I find the
> NASA hypothesis quite convincing.
I think that a few simple calculations will show that the QR is not
producing much compression in comparison to the tension and
compression caused by chain pull and rider load.
Ross Ruske
> Whether hollow axles are made of better material may be another
> parameter to consider but good track axles are at least as durable as
> QR axles of the same OD.
>
Given the same material and OD, the hardening process affects more of
the material in a hollow axle (from the inside as well as the
outside), than it does on a solid axle.
Jon Isaacs
>the material in a hollow axle (from the inside as well as the
>outside), than it does on a solid axle.
Depends on the material. I imagine most axles are made from tempered steel so
it shouldn't make too much difference.
jon isaacs
jobst....@stanfordalumni.org
>> Whether hollow axles are made of better material may be another
>> parameter to consider but good track axles are at least as durable
>> as QR axles of the same OD.
> Given the same material and OD, the hardening process affects more
> of the material in a hollow axle (from the inside as well as the
> outside), than it does on a solid axle.
Could you describe the "hardening" process you believe axles receive
and how that is different with a bore in the axle? What brand of axle
do you have in mind?
Bluto
> Ross Ruske writes:
>
> > Given the same material and OD, the hardening process affects more
> > of the material in a hollow axle (from the inside as well as the
> > outside), than it does on a solid axle.
>
> Could you describe the "hardening" process you believe axles receive
> and how that is different with a bore in the axle? What brand of axle
> do you have in mind?
Carburizing would have the effect Ross describes, as would some
variations of heating & quenching. I know of no axles that are
carburized, though.
It's not difficult to imagine that the different cooling rates of
solid and hollow axles upon quenching would produce different minimum
hardnesses in their sections. How much difference is another matter,
of course.
I suspect that any disproportionate correlation between solid axles
and bending might have something to do with the fact that solid rears
are usually 9.5mm and hollow rears are usually 10mm. It's
indisputable that most horribly cheap axles of unknown and suspect
material are solid, too.
Chalo Colina
Ross Ruske
> Could you describe the "hardening" process you believe axles receive
> and how that is different with a bore in the axle? What brand of axle
> do you have in mind?
>
I don't know what "hardening" processes are normally used on axles. I
have in mind, campagnolo and shimano axles that are subject to a
"tempering" process that occurs subsequent to the machining
operations.
I'm not familiar with a "hardening" process that would penetrate an
entire solid axle. Therefore, the bore in an axle provides additional
surface area for a "hardening" process to affect the material.
Assuming that a "tempering" process penetrates the axle material to a
depth of one half the hollow tube thickness, it would completely
"harden" a hollow axle, but only have half the effect on a solid axle.
Ross
jobst....@stanfordalumni.org
>> Could you describe the "hardening" process you believe axles
>> receive and how that is different with a bore in the axle? What
>> brand of axle do you have in mind?
> I don't know what "hardening" processes are normally used on axles.
> I have in mind, Campagnolo and Shimano axles that are subject to a
> "tempering" process that occurs subsequent to the machining
> operations.
You mean you can see that the axle went through a "bluing" process
because it is dark. That doesn't mean that the axle is hardened. In
fact if you took a file to it, you'd see that it is probably annealed
for stress relieving after machining because the metal is dead soft as
far as hardening is concerned.
> I'm not familiar with a "hardening" process that would penetrate an
> entire solid axle. Therefore, the bore in an axle provides
> additional surface area for a "hardening" process to affect the
> material. Assuming that a "tempering" process penetrates the axle
> material to a depth of one half the hollow tube thickness, it would
> completely "harden" a hollow axle, but only have half the effect on
> a solid axle.
Heat treatment isn't a rinse process that would be enhanced by vent
such as an axle bore.
Not only are you not "familiar with a "hardening" process that would
penetrate an entire solid axle", but you are unfamiliar with surface
heat treatments commonly used on such parts because it would have no
effect on axle strength, the inside wall of the bore being relatively
unstressed when the axle is subjected to bending, the only load an
axle carries, the one that causes axle failure. I detect a case of
MAS.
Jon Isaacs
>entire solid axle.
The most common hardening process for steel is heating it to around 1500F and
then quenching it in either water or oil. Chrome-Moly steels like 4340 and also
Tool steels which are extremely hard are generally done this way. Some steels
such as 17-4 PH and maraging steels are hardened by aging them in an oven at
about 900F.
These processes result in the entire cross-sections being hardened, though
small local variations occur when quenching. Aging processes do not have this
issue.
Strain hardening or cold working is another way to harden steel. This also is
provides first order hardness though it can be somewhat isotropic.
>Assuming that a "tempering" process penetrates the axle material to a
>depth of one half the hollow tube thickness, it would completely
>"harden" a hollow axle, but only have half the effect on a solid axle.
It is important to have your definitions clear. Tempering is not a hardening
process, tempering is the process of taking a hardened steel which may be quite
brittle and then reheating it to reduce the hardness and increase the
ductility. In general, the higher the tempering temperature, the greater the
reduction in hardness and the greater the increase in ductility/reduction in
brittle behavior. 4340 for example which might be somewhere in the mid 40s on
the Rockwell C scale will be "drawn back" to something like maybe 40 with an
associated reduction in tensile strength from about 270 ksi to about 200 ksi.
The bottomline is that most hardening processes are thermal and to a first
order they cause a uniform hardness throughout the piece.
Nitriding and other surface hardening techniques are only used when it
desireable to harden only the surface or when it is cheaper to do so. The
normal reason for using localized hardening techniques is to increase wear
resistance. A piece that is nitrided would most like be hardened by heating
and quenching first.
With a bicycle axle, surface hardness is not helpful, in fact it would be
detrimental because it could help cause the development of localized cracks
which could then propagate.
My guess is that most decent axles are made from Chrome-moly and heat treated
and tempered.
jon isaacs
stu
don't know just asking
Jon Isaacs
>wouldn't they need to be hard where the bearings run?
>don't know just asking
That is true but the bearing run on the races not on the axle. THe races are
hardened.
Jon Isaacs
A Muzi
news:3e56acf8$0$27765$afc3...@news.optusnet.com.au...
> wouldn't they need to be hard where the bearings run?
> don't know just asking
No because the bearings run on the cone ( the part which screws on the
axle).. Cones are very hard.
Axles are indeed not hardened as anyone who's reformed a damaged thread
with a file can attest. The material is quite soft.
stu
l was thinking about bb not axles