butted spokes (?)

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

Quoted message said:

I'm building a bike for XC races and I'd like it to be reasonably light. I
thought of using butted spokes (my frand told me taht u can save as much as
100grams per wheel). My questions are:

1) does it make any sense to use butted spokes at all?
2) is yes, is there any big difference in their durability (for instance
standard 2.0 stainless steel spokes vs 2.0 - 1.5 - 2.0 spokes) ?
3) what spokes would you reccomend (thickness) and why ?

Now some data: I weight around 170 lbs, the rim I want to use is mavic 317
DISC, DT hubs, hydro disc brakes, the bike is a hardtail.

Thx in advance for any help.

I found spokes swaged to as thin as 1.6 mm are recommended by manufacturers
to NOT be used in disc brake wheels; presumably this restrictions has
something to do with the forces exerted through spokes with the use of hub
disc brakes. (2.0 x 1.8 swaged spokes are Ok and may be optimal; however,
there are spokes available with ends greater than 2.0 that are marketed for
some hub disc brake applications.) Disc brake wheels I've used for road
application came with 2.0 mm x 1.8 mm "Race" spokes manufactured by Sapim.
http://www.sapim.be/

Best information source for the rest of your questions regarding use of
swaged (aka "butted"😉 spokes, IMO, is "The Bicycle Wheel" by Jobst Brandt.
http://sheldonbrown.com/harris/tools/wheel.html#books

--
Mykal Crooks
Seattle, WA

Quoted message said:

I'm building a bike for XC races and I'd like it to be reasonably light. I
thought of using butted spokes (my frand told me taht u can save as much
as
100grams per wheel). My questions are:

1) does it make any sense to use butted spokes at all?
2) is yes, is there any big difference in their durability (for instance
standard 2.0 stainless steel spokes vs 2.0 - 1.5 - 2.0 spokes) ?
3) what spokes would you reccomend (thickness) and why ?

The purpose of using butted spokes is to produce a more durable wheel, not
to save weight. The weight savings will be minimal.

Spokes are most likely to break at the elbow (where they attach to the hub)
or at the nipple. Butted spokes provide strength at those areas while the
thinner center portion gives greater elasticity. The greater elasticity
makes it less likely that a spoke will go slack when hitting bumps. When
spokes go slack (even momentarily) the nipple can loosen, causing the wheel
to go out of true. Once a nipple starts to loosen, the process will continue
until the spoke becomes completely slack.

I would not recommend 2.0-1.5-2.0 spokes. The difference in the diameters of
the butted vs. unbutted sections is too great, and you'll have lots of
trouble with spoke wind-up when tensioning them. For your application, I
would use 2.0-1.8-2.0 spokes (DT Competition).

Art Harris

Quoted message said:

I'm building a bike for XC races and I'd like it to be reasonably light. I
thought of using butted spokes (my frand told me taht u can save as much as
100grams per wheel). My questions are:

You use butted spokes for wheel strength, not weigh savings.

Quoted message said:

1) does it make any sense to use butted spokes at all?
2) is yes, is there any big difference in their durability (for instance
standard 2.0 stainless steel spokes vs 2.0 - 1.5 - 2.0 spokes) ?
3) what spokes would you reccomend (thickness) and why ?

Use 14/15/14 gauge spokes(2mm/1.8mm/2mm), and lace them inside pulling
for a disc wheel.

Quoted message said:

Now some data: I weight around 170 lbs, the rim I want to use is mavic 317
DISC, DT hubs, hydro disc brakes, the bike is a hardtail.

Thx in advance for any help.

Mykal said:

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

Quoted message said:

I'm building a bike for XC races and I'd like it to be reasonably light. I
thought of using butted spokes (my frand told me taht u can save as much as
100grams per wheel). My questions are:

1) does it make any sense to use butted spokes at all?
2) is yes, is there any big difference in their durability (for instance
standard 2.0 stainless steel spokes vs 2.0 - 1.5 - 2.0 spokes) ?
3) what spokes would you reccomend (thickness) and why ?

Now some data: I weight around 170 lbs, the rim I want to use is mavic 317
DISC, DT hubs, hydro disc brakes, the bike is a hardtail.

Thx in advance for any help.

I found spokes swaged to as thin as 1.6 mm are recommended by manufacturers
to NOT be used in disc brake wheels; presumably this restrictions has
something to do with the forces exerted through spokes with the use of hub
disc brakes. (2.0 x 1.8 swaged spokes are Ok and may be optimal; however,
there are spokes available with ends greater than 2.0 that are marketed for
some hub disc brake applications.) Disc brake wheels I've used for road
application came with 2.0 mm x 1.8 mm "Race" spokes manufactured by Sapim.
http://www.sapim.be/

Best information source for the rest of your questions regarding use of
swaged (aka "butted"😉 spokes, IMO, is "The Bicycle Wheel" by Jobst Brandt.
http://sheldonbrown.com/harris/tools/wheel.html#books

jobst calls them all "swaged" but that's because he's seemingly unaware
of the fact that different spokes are made by different methods. some
are indeed swaged, but some others are drawn and yet others are ground &
polished. the generic term for /all/ reduced diameter spokes is
therefore "butted". don't let anyone who knows nothing about these
different production methods tell you otherwise.

Qui si parla Campagnolo said:

Quoted message said:

I'm building a bike for XC races and I'd like it to be reasonably light. I
thought of using butted spokes (my frand told me taht u can save as much as
100grams per wheel). My questions are:

You use butted spokes for wheel strength, not weigh savings.

make that "fatigue strength". strictly speaking, a straight gauge spoke
is stronger than butted in static loading.

Quoted message said:

Quoted message said:

1) does it make any sense to use butted spokes at all?
2) is yes, is there any big difference in their durability (for instance
standard 2.0 stainless steel spokes vs 2.0 - 1.5 - 2.0 spokes) ?
3) what spokes would you reccomend (thickness) and why ?

Use 14/15/14 gauge spokes(2mm/1.8mm/2mm), and lace them inside pulling
for a disc wheel.

absolutely.

Quoted message said:

Quoted message said:

Now some data: I weight around 170 lbs, the rim I want to use is mavic 317
DISC, DT hubs, hydro disc brakes, the bike is a hardtail.

Thx in advance for any help.

Quoted message said:

I'm building a bike for XC races and I'd like it to be reasonably light. I
thought of using butted spokes (my frand told me taht u can save as much as
100grams per wheel). My questions are:

1) does it make any sense to use butted spokes at all?

yes, superior fatigue strength.

Quoted message said:

2) is yes, is there any big difference in their durability (for instance
standard 2.0 stainless steel spokes vs 2.0 - 1.5 - 2.0 spokes) ?

yes. go to sapim.be and dig about for their fatigue strength tables.

Quoted message said:

3) what spokes would you reccomend (thickness) and why ?

2mm/1.8mm/2mm. best trade-off between fatigue strength and stiffness.
stiffness is important for lateral stability.

Quoted message said:

Now some data: I weight around 170 lbs, the rim I want to use is mavic 317
DISC, DT hubs, hydro disc brakes, the bike is a hardtail.

Thx in advance for any help.

Quoted message said:

methods. some are indeed swaged, but some others are drawn and yet
others are ground & polished.

Does Wheelsmith do the last one? I've noticed that...

--
Phil, Squid-in-Training

Quoted message said:

Disc brake torque is no greater spoke load than peak pedaling torque
and it is distributed to both sides of the wheel, which pedaling
torque is not.

Why is it distributed? Disc brake torque is applied in pretty much the
same place on the wheel as torque through a freewheel, so wouldn't it be
mostly on the brake-side spokes, like pedaling torque is on drive side? In
both cases you essentially add torque at one hub flange.

Jasper

jim beam said:

Quoted message said:

3) what spokes would you reccomend (thickness) and why ?

2mm/1.8mm/2mm. best trade-off between fatigue strength and stiffness.
stiffness is important for lateral stability.

Rinard found that lateral stiffness of a wheel changed much less than
the difference in spoke stiffness (look for #7 at the bottom):

http://www.sheldonbrown.com/rinard/wheel/

A 90% increase in spoke siffness (1.45mm dia to 2mm dia) produced only
an 11% increase in lateral wheel stiffness.

jim beam said:

go to sapim.be and dig about for their fatigue strength tables.

http://www.sapim.be/index.php?st=products&sub=spokes&detail=fatiguetest

If I calculated correctly their "fatigue test" results seem a little
odd. 1,000,000 wheel revolutions is only 1,340 miles
(27*pi/12/5280*1,000,000). Even the CX-rays with 3,500,000 revolutions
only get 4,690 miles.

I would be nice to know more about that testing...

Ron Ruff said:

jim beam said:

go to sapim.be and dig about for their fatigue strength tables.

http://www.sapim.be/index.php?st=products&sub=spokes&detail=fatiguetest

If I calculated correctly their "fatigue test" results seem a little
odd. 1,000,000 wheel revolutions is only 1,340 miles
(27*pi/12/5280*1,000,000). Even the CX-rays with 3,500,000 revolutions
only get 4,690 miles.

I would be nice to know more about that testing...

all i've discovered is that it was done by cycling from 90kgf to zero.
that's much higher than most wheels see in service. being as fatigue
life is usually regarded as having a logarithmic relation to stress, you
can see that your mileage will quickly increase with decreasing stress
cycle.

Ron Ruff said:

jim beam said:

Quoted message said:

3) what spokes would you reccomend (thickness) and why ?

2mm/1.8mm/2mm. best trade-off between fatigue strength and stiffness.
stiffness is important for lateral stability.

Rinard found that lateral stiffness of a wheel changed much less than
the difference in spoke stiffness (look for #7 at the bottom):

http://www.sheldonbrown.com/rinard/wheel/

A 90% increase in spoke siffness (1.45mm dia to 2mm dia) produced only
an 11% increase in lateral wheel stiffness.

sure, so why don't you include damon's comment about the rim
contributing to wheel stiffness as well?

jim beam said:

Quoted message said:

sure, so why don't you include damon's comment about the rim
contributing to wheel stiffness as well?

I thought that was obvious... at any rate it was the same rim in both
tests... and I suspect that on an MTB wheel the rim stiffness would
contribute even more, making the effect of spoke stiffness even less.

jim beam said:

Ron Ruff said:

If I calculated correctly their "fatigue test" results seem a little
odd. 1,000,000 wheel revolutions is only 1,340 miles
(27*pi/12/5280*1,000,000). Even the CX-rays with 3,500,000 revolutions
only get 4,690 miles.

I would be nice to know more about that testing...

all i've discovered is that it was done by cycling from 90kgf to zero.
that's much higher than most wheels see in service. being as fatigue
life is usually regarded as having a logarithmic relation to stress, you
can see that your mileage will quickly increase with decreasing stress
cycle.

So, they stressed the spokes in an unusual way to get them to break
sooner... fairly standard, I guess. Still, it seems odd that they would
have presented it as "wheel revolutions" when it really isn't... and it
makes their spokes look bad.

Also, that 200lb cycle is roughly only 20% of the tensile strength that
they list elsewhere... a huge difference between fatigue and static
strength.

Do you know of any other (hopefully better) online data regarding spoke
fatique and strength?

Ron Ruff said:

jim beam said:

Ron Ruff said:

If I calculated correctly their "fatigue test" results seem a little
odd. 1,000,000 wheel revolutions is only 1,340 miles
(27*pi/12/5280*1,000,000). Even the CX-rays with 3,500,000 revolutions
only get 4,690 miles.

I would be nice to know more about that testing...

all i've discovered is that it was done by cycling from 90kgf to zero.
that's much higher than most wheels see in service. being as fatigue
life is usually regarded as having a logarithmic relation to stress, you
can see that your mileage will quickly increase with decreasing stress
cycle.

So, they stressed the spokes in an unusual way to get them to break
sooner... fairly standard, I guess.

yup.

Quoted message said:

Still, it seems odd that they would
have presented it as "wheel revolutions" when it really isn't...

a translation thing?

Quoted message said:

and it
makes their spokes look bad.

don't think so. as a relative measure between sapim's different spokes,
it's tells you what you need to know. as an absolute measure between
brands, i think it interesting that none of the other manufacturers have
the minerals to publish any fatigue info at all!

Quoted message said:

Also, that 200lb cycle is roughly only 20% of the tensile strength that
they list elsewhere... a huge difference between fatigue and static
strength.

sure, there's a spoke elbow on the bottom of this spoke bending back &
forth on each stress cycle. that'll raise the stress in the skin of the
bend considerably. you'll never see that reflected in static loading.

Quoted message said:

Do you know of any other (hopefully better) online data regarding spoke
fatique and strength?

carl fogel posted a pdf by someone named prof. gavin a while back. istr
that it contained fatigue testing. other than that, your googling is as
good as mine.

Southern Comfort said:

jobst calls them all "swaged" but that's because he's seemingly
unaware of the fact that different spokes are made by different
methods. some are indeed swaged, but some others are drawn and yet
others are ground & polished. the generic term for /all/ reduced
diameter spokes is therefore "butted". don't let anyone who knows
nothing about these different production methods tell you otherwise.

"Butted" comes from the upsetting of the end of a rod to make a
thicker feature such as a spoke head or to thicken the end on which
threads are to be cut. However, spokes are not thickened but thinned
by swaging, a metal forming process that can be done by hammering on
an anvil as was done in the days of yore, or by drawing through a
split die clamped onto the spoke mid-section.

DT chose to use the split die while hammering it in rotation around
the spoke. This not only reduces the cross section but work hardens
it. Just drawing the spoke through a split die (with helical seam)
may be faster but usually leaves drawing marks that must be polished
out. Toward the end of their days in business, Stella spokes had
terrible draw marks on their swaged spokes. The process can be
simulated by other means such as metal removal, something that does
not make as strong a spoke as swaging.

Jobst Brandt

Jasper Janssen said:

Quoted message said:

Disc brake torque is no greater spoke load than peak pedaling
torque and it is distributed to both sides of the wheel, which
pedaling torque is not.

Quoted message said:

Why is it distributed? Disc brake torque is applied in pretty much
the same place on the wheel as torque through a freewheel, so
wouldn't it be mostly on the brake-side spokes, like pedaling torque
is on drive side? In both cases you essentially add torque at one
hub flange.

Hubs made for disc brakes generally have a large diameter spool
between flanges. If they don't don't buy them. This is especially
true for rear hubs. The good disc brake front hubs I have seen have
such a spool, so braking spoke load is fairly equal on both sides of
the wheel.

Jobst Brandt

Quoted message said:

Jasper Janssen said:

Quoted message said:

Disc brake torque is no greater spoke load than peak pedaling
torque and it is distributed to both sides of the wheel, which
pedaling torque is not.

Quoted message said:

Why is it distributed? Disc brake torque is applied in pretty much
the same place on the wheel as torque through a freewheel, so
wouldn't it be mostly on the brake-side spokes, like pedaling torque
is on drive side? In both cases you essentially add torque at one
hub flange.

Hubs made for disc brakes generally have a large diameter spool
between flanges.

but transmission is still less on one side than the other...

Quoted message said:

If they don't don't buy them. This is especially
true for rear hubs. The good disc brake front hubs I have seen have
such a spool, so braking spoke load is fairly equal on both sides of
the wheel.

Jobst Brandt

Ron Ruff said:

jim beam said:

Ron Ruff said:

If I calculated correctly their "fatigue test" results seem a little
odd. 1,000,000 wheel revolutions is only 1,340 miles
(27*pi/12/5280*1,000,000). Even the CX-rays with 3,500,000 revolutions
only get 4,690 miles.

I would be nice to know more about that testing...

all i've discovered is that it was done by cycling from 90kgf to zero.
that's much higher than most wheels see in service. being as fatigue
life is usually regarded as having a logarithmic relation to stress, you
can see that your mileage will quickly increase with decreasing stress
cycle.

So, they stressed the spokes in an unusual way to get them to break
sooner... fairly standard, I guess. Still, it seems odd that they would
have presented it as "wheel revolutions" when it really isn't... and it
makes their spokes look bad.

Also, that 200lb cycle is roughly only 20% of the tensile strength that
they list elsewhere... a huge difference between fatigue and static
strength.

Do you know of any other (hopefully better) online data regarding spoke
fatique and strength?

Dear Ron,

If you haven't seen it, here's a paper on a variety of spoke
details:

http://www.duke.edu/~hpgavin/papers/HPGavin-Wheel-Paper.pdf

It mentions the Wheelsmith-Stanford testing of spokes to
destruction from some years ago.

Professor Gavin was kind enough to send me the details of
the Wheelsmith tests, but while they were on their way, one
of our more obnoxious anonymous nitwits became so
unspeakable that I apologized to Professor Gavin for
dragging him into our cesspool and promised not to even open
the envelope when it arrived.

[Carl stares longingly at an unopened manila envelope with a
$3.85 02-22-2005 postmark. Feels like more than 30 pages,
much too thick to read by holding the envelope up to the
light. Probably full of really fascinating stuff. Cursed
ethics! Back to the shelf. Maybe someone else will find a
copy.]

Carl Fogel