Spoke hole cracking - my building technique at fault ?
Andy Dingley
spoke hole cracks 8-(
It's the rear on my daily commuter - unsuspended steel MTB frame, shod
with (old style) Top Tourings. Six years of near daily use, no
downhilling, but a fair few kerbs to bounce over. The rim itself is a
Mavic 217 - chosen because they're supposedly robust. Hub is an LX and
the spokes are DT.
So what went wrong here ? Should I blame my beginner's wheelbuilding
technique (did I overtension it ?) or should I just blithely shrug it
off onto anodising ? It looks like all driver-side holes are equally
affected
Is this a reasonable rim lifetime ? There's certainly a lot left in
the sidewalls.
--
Smert' spamionam
jim beam
necessary, share the cost with some friends.
(Pete Cresswell)
>So what went wrong here ? Should I blame my beginner's wheelbuilding
>technique (did I overtension it ?) or should I just blithely shrug it
>off onto anodising ? It looks like all driver-side holes are equally
>affected
I had the same experience with three Mavic 517's used as rear wheels. All three
built professionally - each by a different builder - so somebody'd have a hard
time convincing me it was the build...especially since I broke down and bought a
tensiometer to build my own and found tensions on all 3 to be within Mavic's
spec.
My current opinion? Those rims just aren't intended for somebody as heavy as I
am (220).
--
PeteCresswell
daveornee
It sounds more like a problem with the rim itself than builder skill.
Since the area around all spokes on the drive side are cracking, it
would be reasonable to surmise that your spoke tension was high and
even. I am riding a wheel I built with Mavic 217 6 years ago and have
about 25,000 miles on it. The front rim, built at the same time
developed a clicking at the rim joint due to the splice material sliding
around near the joint after 12,000 miles. The rear has jumped curbs,
fallen in potholes that I couldn't clear, etc. It is the silver color
and still has no cracks.
Heat treating, extrusion process, application of eyelets all have
tolerances. Your rim may have been out-of-tolerance and/or near the
bottom end in all areas. Is it Mavic CD hard anodized? Mavic's quality
control (or lack there of) hasn't proven to be great. Usually I spot
sample problems before the build at the joint area. I have had good
response to getting replacement via a Mavic dealer. However, after 6
years, I doubt you would have any luck on this rim. Mavic X618 (eyelet
connects both rim walls) or X517 (single eyelet) are very close in ERD
and should work well with your existing spoke length. If you find a F519
and your spokes were bordering on being too long, this rim is a little
wider and stronger the the X517.
--
G.T.
> what's your spoke tension? a park tool to measure it is ~$50. if
> necessary, share the cost with some friends.
>
So you're saying we should build undertensioned and weaker wheels to make
up for the poor quality of Mavic rims?
Greg
--
"Destroy your safe and happy lives before it is too late,
the battles we fought were long and hard,
just not to be consumed by rock n' roll..." - The Mekons
Tim McNamara
> what's your spoke tension? a park tool to measure it is ~$50.
And of questionable accuracy. You seem to have a spoke tension
fetish going on in these threads.
jim beam
limit and are not tolerant of use out of spec.
on my own cracked 517, it cracked as i deliberately overtensioned it!
the wheels i have that are built to spec have not cracked - same type rim.
there /is/ a correleation. repeated recommendation on this forum to
have spokes "as tight as possible" do nothing for wheel stiffness and
have a strongly negative impact on rim life. that's why a tensiometer
is relevant.
G.T.
> no, i'm saying that from my experience, mavics are right at the material
> limit and are not tolerant of use out of spec.
>
> on my own cracked 517, it cracked as i deliberately overtensioned it!
> the wheels i have that are built to spec have not cracked - same type rim.
>
> there /is/ a correleation. repeated recommendation on this forum to
> have spokes "as tight as possible" do nothing for wheel stiffness and
> have a strongly negative impact on rim life.
Sorry, but undertensioned spokes under a heavy guy like me means constantly
out of true rims.
jim beam
to go. i kept all my subsequent wheels at about 1100N drive side rear &
as even as possible and have not had any further problems.
jb
David Damerell
I do agree with the recommendation of the tool, though. It's very useful,
as an amateur wheelbuilder, to be able to get a decent feel for what
1000N actually is like.
--
David Damerell <dame...@chiark.greenend.org.uk> flcl?
Werehatrack
<din...@codesmiths.com> may have said:
>Just noticed that my first ever home-built wheel is starting to show
>spoke hole cracks 8-(
>
>It's the rear on my daily commuter - unsuspended steel MTB frame, shod
>with (old style) Top Tourings. Six years of near daily use, no
>downhilling, but a fair few kerbs to bounce over. The rim itself is a
>Mavic 217 - chosen because they're supposedly robust.
http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=mavic+217+crack*
Your technique is not the problem, in my opinion.
--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.
Carl Fogel
Dear Tim,
Most mechanics share Jim's fetish for tension
values. They use torque wrenches (whose accuracy
is often less than admirable) to tension all
sorts of threaded fasteners that undergo far
less variation than spokes.
The more important the tension is, the more
likely professional mechanics are to use
torque wrenches. Even a rough measurement
tool tends to be better than the seat of
our pants.
It's a shame that bicycle nipples and threaded
spokes are so twisty that we use tensio-meters.
Many motorcycle mechanics use special torque
wrenches to work on their beefier spokes:
http://www.mxbike.com/catalog/Fasst+Company+Spoke+Torque+Wrench
(Sorry, Jim, but it seemed like an apt spot to
drag the dreaded engine-powered beasts in.)
Carl Fogel
daveornee
> Tim McNamara <tim...@bitstream.net> wrote in message news:<m2k72ndex6.fsf@Stella-
> Blue.local>...
> > jim beam <u...@ftc.gov> writes:
> >
> > > what's your spoke tension? a park tool to measure it is ~$50.
> >
> > And of questionable accuracy. You seem to have a spoke tension fetish
> > going on in these threads.
> Dear Tim,
> Most mechanics share Jim's fetish for tension values. They use torque
> wrenches (whose accuracy is often less than admirable) to tension all
> sorts of threaded fasteners that undergo far less variation than spokes.
> The more important the tension is, the more likely professional
> mechanics are to use torque wrenches. Even a rough measurement tool
> tends to be better than the seat of our pants.
> It's a shame that bicycle nipples and threaded spokes are so twisty that
> we use tensio-meters. Many motorcycle mechanics use special torque
> wrenches to work on their beefier spokes:
> www.mxbike.com/catalog/Fasst+Company+Spoke+Torque+Wrench
> (Sorry, Jim, but it seemed like an apt spot to drag the dreaded engine-
> powered beasts in.)
> Carl Fogel
Torque wrenches have their place, but I doubt that they really bo much
good in any spoke applications, including motorcycles. (however,
something may be better than nothing) Even the most accurate torque
wrench has limits of accuracy. Thread prepartion, washers, head
prepartion, operating the torque wrench in it's specified range, and
calibration, all have a lot to do with attaining correct "tightness".
Spoke tension has a correct value for each application. Balancing spoke
tension is even more important than getting the tension to a precise
number. Using a spoke tension measuring device that has reasonable
resolution and precise repeatability will help insure that spokes carry
their portion of the load. Spoke alignment, removing any residual wind-
up, and stress relieving are also very important to insure the spokes
"stay where you put them".
--
Jose Rizal
> Most mechanics share Jim's fetish for tension
> values. They use torque wrenches (whose accuracy
> is often less than admirable) to tension all
> sorts of threaded fasteners that undergo far
> less variation than spokes.
Not true in general, and certainly not most mechanics, auto or bike. In
fact, my observation is quite the opposite; many mechanics palce a lot
of trust in their ability to "feel" the "right" amount of
tension/tightness in bolts, screws, and such things, especially when
many of these are involved.
> The more important the tension is, the more
> likely professional mechanics are to use
> torque wrenches.
Not convinced. Next time you have your car serviced, see how many mechs
at your local garage use torque wrenches.
Jose Rizal
> no, i'm saying that from my experience, mavics are right at the material
> limit and are not tolerant of use out of spec.
>
> on my own cracked 517, it cracked as i deliberately overtensioned it!
> the wheels i have that are built to spec have not cracked - same type rim.
>
> there /is/ a correleation. repeated recommendation on this forum to
> have spokes "as tight as possible" do nothing for wheel stiffness and
> have a strongly negative impact on rim life. that's why a tensiometer
> is relevant.
My experience is quite different, and I've had many Mavics. These
certainly are all not "right at the material limit", which is a
misnomer; it's not the material that's faulty, it's the dimension of the
rim build.
It's doubtful you've cracked your 517 in over-tensioning spokes; in all
rims I've had, tacoing occurred at excessive spoke tension before any
cracks developed. It's also highly unlikely that Mavic rims crack due
to brute force on spoke tension; fatigue failure is what these fail
from.
As far as your claim that having spokes as tight as possible having a
"strongly negative impact on rim life", please explain the mechanism for
this theory.
Jose Rizal
> Tim McNamara <tim...@bitstream.net> wrote:
> >jim beam <u...@ftc.gov> writes:
> >>what's your spoke tension? a park tool to measure it is ~$50.
> >And of questionable accuracy. You seem to have a spoke tension
> >fetish going on in these threads.
>
> I do agree with the recommendation of the tool, though. It's very useful,
> as an amateur wheelbuilder, to be able to get a decent feel for what
> 1000N actually is like.
The best use of a tensiometer is for ensuring even tensioned spokes.
dianne_1234
>jim beam:
>
>> no, i'm saying that from my experience, mavics are right at the material
>> limit and are not tolerant of use out of spec.
>>
>> on my own cracked 517, it cracked as i deliberately overtensioned it!
>> the wheels i have that are built to spec have not cracked - same type rim.
>>
>> there /is/ a correleation. repeated recommendation on this forum to
>> have spokes "as tight as possible" do nothing for wheel stiffness and
>> have a strongly negative impact on rim life. that's why a tensiometer
>> is relevant.
>
>My experience is quite different, and I've had many Mavics. These
>certainly are all not "right at the material limit", which is a
>misnomer; it's not the material that's faulty, it's the dimension of the
>rim build.
Exactly. Mavic has apparently made the rim walls thinner and thinner,
so now it's possible to fail a rim in modes we never saw before.
>It's doubtful you've cracked your 517 in over-tensioning spokes; in all
>rims I've had, tacoing occurred at excessive spoke tension before any
>cracks developed. It's also highly unlikely that Mavic rims crack due
>to brute force on spoke tension; fatigue failure is what these fail
>from.
>
>As far as your claim that having spokes as tight as possible having a
>"strongly negative impact on rim life", please explain the mechanism for
>this theory.
Modified Goodman curve?
Qui si parla Campagnolo
mechs
at your local garage use torque wrenches. >><BR><BR>
The guy that services my New Beetle uses a torque wrench all the time for
things that are required to be set at a torque..I've seen him use it.
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
Carl Fogel
Dear Jose,
You may be confusing routine service folk with
professional mechanics.
While the service fellows who change oil, tires, spark
plugs, alternators, and even water pumps have little use
for torque wrenches, the mechanics who work on actual
engines use them regularly, where tension matters.
This is analogous to the fellows who tighten seat
bolts, quick-release skewers, derailleur parts, brake
pieces, pedals, and even bottom brackets and axle
cones, as opposed to people who are tensioning spokes.
Even if you're just putting the brick-simple cylinder
head back on an air-cooled single-cylinder two-stroke
(a finned plate with a dome, a spark plug hole, and some
holes for the mounting studs), you want to use a torque
wrench in the prescribed pattern, which usually consists
of going around all the nuts in a criss-cross pattern at
a low tension and then again at a higher tension.
The reason is that you want to press the head down as
evenly as possible onto the soft metal gasket and to
have the tension close to what the engineers figured
out would be a good idea when the violent explosions
underneath the head begin heating everything up and
the studs expand along with everything else. (How much
the gasket is compressed also affects engine compression.)
If you get the torque too far wrong, you'll notice nasty
explosive blasts where the loose head gasket is leaking,
or else even nastier blasts where the too-tight head broke
a stud and the gasket is leaking even worse.
On more complicated four-stroke engines, with water
cooling, and with multiple cylinders (cars), things
become even trickier. It helps to have things over-built
so that you can get away with mistakes, but if the
fellow doing actual engine work on your car (as opposed
to oil changes) doesn't keep a torque wrench handy,
find another mechanic.
The same sort of logic applies to the go/no-go gauges
that professional bike mechanics like Peter Chisholm,
Andrew Muzi, John Dacey, Sheldon Brown, and others use
to check threads--they get better results when they
measure. And no engine mechanic wants to set valves or
old-fashioned breaker points without feeler gauges.
Think of tire pressure. We can estimate it by squeezing
well enough, but most of us end up measuring it because
it gives better results than the seats of our pants.
For bicycle spokes, the usual idea is to tighten things
until you notice local rim yield and then back off a
bit (or maybe a smidgen, which equals 5/4's of a bit).
Helps to remember to lubricate things first, and I forget
if it's only 0.5 smidgens if the rim begins to yield when
you're grabbing the spokes to stress relieve them.
But with fewer and fewer spokes and lighter and lighter
wheels, more and more people are starting to think like
real mechanics and measuring spoke tension instead of
using the seats of their pants.
Since bicycle spokes and nipples are so tiny, torque
readings at the nipple are unlikely to say much--even
tiny imperfections in the threads or in how the spoke
seats on the rim (even when oiled) make torque readings
next to useless (think of spoke wind-up and its effect
on a torque wrench). But a tensio-meter gives a fair
notion of tension and helps people build better bike
wheels.
As always, the old guard disdains and even rails at the
new-fangled notion. Doctors do this, computer programmers
do it, mechanics do it, even chefs do it. In Mark Twain's
day, the riverboat pilots scorned the notion of getting
together in a union and sharing information about the
depths, snags, and marks needed to avoid sinking steamboats.
Eventually, the insurance companies forced the old boys to
join the modern world, and fewer steamboats sank.
Any day now, I'll break down and buy a tensio-meter. I
don't build wheels, but Jim Beam has privately hinted
in a gracious and tactful fashion that it's a cheap and
obvious tool for anyone interested in this kind of stuff.
Carl Fogel
Carl Fogel
Dear Dave,
We agree that torque wrenches probably don't have much
value for thin bicycle spokes and that tensio-meters
are the right tool for even tension and fair for measuring
how much the even tension actually is.
But Honda thinks that torque wrench values work for their
motorcycle spokes, which are much thicker.
(I don't know how the even thicker-spoked car wheels of
British sports cars were tensioned. Perhaps someone who
worked on them will have something interesting to say.)
It may help readers unfamiliar with such things to describe
the difference in spokes. My road bicycle's 700c rear rim
uses 2.0mm x 1.8mm x 2.0mm double-butted spokes, 295mmm long
with a roughly 4mm hub-head and nipples about 3.5mm in a
36-spoke cross-3 pattern.
My flimsy trials motorcycle's 18-inch rim rear wheel uses
3.5mm x 3.5mm x 4.0mm hub-butted spokes, 165mm long with a
roughly 7mm hub head and nipples about 6mm in a 36-spoke
cross-2 pattern.
Here's a picture:
http://home.comcast.net/~carlfogel/download/spokes.jpg
One result of this difference in thickness is stress-relief.
I doubt that anyone can stress relieve thick, short motorcycle
spokes by simply grabbing a pair and squeezing them--they don't
budge when tensioned. The bicycle method just doesn't seem to
be part of motorcycle wheel-building. Nor does our familiar
problem of wind-up.
With such strong, thick spoke parts, Honda simply specifies
a range of torque values. The range may be comparable to the
wide range of bicycle wheel manufacturer tension recommendations,
it may have its problems, but that's how the Honda engineers do it.
Carl Fogel
daveornee
difference in spokes. My road bicycle's 700c rear rim uses 2.0mm x 1.8mm
x 2.0mm double-butted spokes, 295mmm long with a roughly 4mm hub-head
and nipples about 3.5mm in a 36-spoke cross-3 pattern.
My flimsy trials motorcycle's 18-inch rim rear wheel uses
3.5mm x 3.5mm x 4.0mm hub-butted spokes, 165mm long with a roughly 7mm
hub head and nipples about 6mm in a 36-spoke cross-2 pattern.
Here's a picture:
http://home.comcast.net/~carlfogel/download/spokes.jpghttp://home.comc-
ast.net/~carlfogel/download/spokes.jpg
One result of this difference in thickness is stress-relief. I doubt
that anyone can stress relieve thick, short motorcycle spokes by simply
grabbing a pair and squeezing them--they don't budge when tensioned. The
bicycle method just doesn't seem to be part of motorcycle wheel-
building. Nor does our familiar problem of wind-up.
With such strong, thick spoke parts, Honda simply specifies a range of
torque values. The range may be comparable to the wide range of bicycle
wheel manufacturer tension recommendations, it may have its problems,
but that's how the Honda engineers do it.
Carl Fogel
Honda engineers may do it, but that doesn't make the procedure correct.
Even exact matching of torque readings of a properly applied accurate
torque wrench won't necessisarily give you even tension or a true wheel.
As I said before, it is better than nothing. Plucking the spokes and
matching their tones as better than the torque wrench method. I agree
that Jobst Brandt's "squeezing pairs" method doesn't work for stress
relieving motorcycle spokes, at least not with my hands. However, a
variant of what Sheldon Brown shows, does work. I used a crow bar near
the crossings. The times I've worked on motorcycle wheels are few, but
when I did, the shop had a spoke tension gague that looked like a Hozan
unit I have seen and used in a few bike shops. Dynamic mechanical
response of spokes in any wheel depend on their tension, not the torque
applied to the nipple. If you get even spoke tension by using a torque
wrench, that is great. I saw a demonstration once, in motorcycle a shop
I visited, where the torques matched precisely, but the tension varied
by over 25%
--
Tom Sherman
> ...
> (I don't know how the even thicker-spoked car wheels of
> British sports cars were tensioned. Perhaps someone who
But not in language fit for a general interest Usenet Newsgroup!
"The Reliable English Sports Car - A Work of Fiction"
Tom Sherman - Quad Cities
jim beam
> jim beam:
>
>
>>no, i'm saying that from my experience, mavics are right at the material
>>limit and are not tolerant of use out of spec.
>>
>>on my own cracked 517, it cracked as i deliberately overtensioned it!
>>the wheels i have that are built to spec have not cracked - same type rim.
>>
>>there /is/ a correleation. repeated recommendation on this forum to
>>have spokes "as tight as possible" do nothing for wheel stiffness and
>>have a strongly negative impact on rim life. that's why a tensiometer
>>is relevant.
>
>
> My experience is quite different, and I've had many Mavics. These
> certainly are all not "right at the material limit", which is a
> misnomer; it's not the material that's faulty, it's the dimension of the
> rim build.
>
> It's doubtful you've cracked your 517 in over-tensioning spokes;
well, i can't prove it to you jose, but they cracked before my very eyes
as i turned the spoke key. believe that or not as you choose.
Antti Salonen
> The best use of a tensiometer is for ensuring even tensioned spokes.
I don't get this. Even tension is easily verified by just plucking the
spokes, unless you are completely tone-deaf. If you want to know the
absolute tension of the spokes, a tensiometer is the only reasonable
way.
Even if the cheap Park Tool tensiometer may be a bit unreliable for
individual spokes, shouldn't it still be fairly accurate if you measure
several spokes of roughly equal tension? You could either ignore a
reading very different from the others or calculate an average.
-as
David Damerell
>Jose Rizal <_@_._> wrote:
>>The best use of a tensiometer is for ensuring even tensioned spokes.
>I don't get this. Even tension is easily verified by just plucking the
>spokes, unless you are completely tone-deaf.
There are levels of tone-deafness. I can distinguish different notes, but
if they are close I cannot tell which is highest. This is a dead loss for
wheelbuilding.
--
David Damerell <dame...@chiark.greenend.org.uk> Kill the tomato!
JP
> Antti Salonen <aksa...@blah.blah.cc.helsinki.fi.invalid> wrote:
> >Jose Rizal <_@_._> wrote:
> >>The best use of a tensiometer is for ensuring even tensioned spokes.
> >I don't get this. Even tension is easily verified by just plucking the
> >spokes, unless you are completely tone-deaf.
>
> There are levels of tone-deafness. I can distinguish different notes, but
> if they are close I cannot tell which is highest. This is a dead loss for
> wheelbuilding.
I am definitely not tone deaf but have a problem plucking spokes to
look for evenly tensioned spokes. The wheel doesn't make a very good
sounding board, the crossed spokes interfere with the tone, you get
all kinds of rattles and extraneous overtones, it's hard to maintain
your reference pitch because changing one spoke has effects on the
tension of others, and a spoke nipple is not exactly an optimized
tuning peg, which causes the pitch to jump. I do think that if you
pluck near the nipple the tone is just about clear enough that you can
use it to get an idea and maybe use it when you're truing the wheel to
help decide which spoke to tighten or loosen, or whether one is
grossly over- or undertightened, but I don't see it as a substitute
for a tensiometer (which I don't have but I could see how they would
make wheelbuilding faster and more precise).
JP