Rim cracks around the spoke holes
Bill Bushnell
are showing radial cracks.
See: http://tinyurl.com/l8hh5v, and the next five photos in the album.
I have ridden this rim at least a few thousand miles, but during its early
life the rim would drift out of true. I would discover that one or more
spokes had gone slack. After truing and evening tension each time as best I
could the rim would stay in true for only a few hundred miles. The last time
I trued the rim I increased tension about 3/4 of a turn on all spokes. This
time the rim has remained true to this day, except now about 1000 miles later
I see the cracks at the spoke holes.
Questions:
1) How long before one of these spokes pulls through? The photos show the
worst of the cracking. Should I stop riding it?
2) What replacement rim would you recommend? These are ISO 559 (MTB) rims.
--
Bill Bushnell
http://pobox.com/~bushnell/
Tim McNamara
Bill Bushnell <mrb...@pobox.com> wrote:
Bill, first off- nice collection of photos of broken bike parts.
Generally well lit and close enough to show detail. Nice job.
Second, I'd stop riding that rim just because it's obviously already
unreliable. I'd be inclined to look for an Alex rim (Chalo can
recommend particulars) or a polished Sun CR18. I have had good results
with the latter, even though it's only a single-ferruled rim.
Mike Jacoubowsky
news:4a886cbe$0$1590$742e...@news.sonic.net...
When the rim requires frequent truing due to the cracks, then it's time
to replace it. It will only get worse. You may not be at that point yet,
but you will be soon. On a 26" rim, it's very easy to overtighten the
spokes without having obvious symptoms (such as a tendency to taco), and
I suspect that may be what happened. For the next wheel, I'd back off on
the tension a bit and use something like DT Spoke Freeze to keep them
from spinning loose when they're under low tension. Yes, I know, a
"properly-built" wheel shouldn't require any sort of spoke locking
compound to keep from loosening up, but in the real world, I find that's
not the case.
If I could recommend a rim guaranteed not to crack, I would. But I
haven't found that rim yet, at least not in a weight that anybody would
want to ride.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
Tom Sherman °_°
Track in 36-H version as a minimum starting point.
--
Tom Sherman - 42.435731,-83.985007
Celebrity culture is an opposite of community, informing us
that these few nonsense-heads matter but that the rest of
us do not. - Jay Griffiths
landotter
> In article <4a886cbe$0$1590$742ec...@news.sonic.net>,
I'd try to match the ERD so the spokes can be reused. If it matches an
Alex DM18 or Adventurer, then the fix will be cheap and strong.
Tom Sherman °_°
If it were my bike, I would use the Alex DM22 or DM24 instead. I suspect
this wheel will carry a significant portion of the total weight and will
see high speed service.
landotter
Those are only available in OEM in the US. The DM18 and Adventurer are
likely the strongest commonly available rims that aren't intended for
downhill. They can stand up to a Chalo, and my own bike + 170 me +
lotsa gear + ohhhh, let's explore this trail on hard skinny tires. ;-)
--D-y
Spocalc, which I believe is linked to in Sheldon Brown's site, has a
table or ERD's (Effective Rim Diameter, "how long the spokes have to
be", depending on lacing pattern, spoke count) for many rims. Your
particular Ritchey OC might well be on there and then you could look
for another listed rim, perhaps one of the ones that have been
recommended in this thread, that matches or gets very close, and do a
rim swap-- maybe get new nipples if yours are a little dog-eared from
repeated tightenings. Check your spokes on the drive side haven't been
gouged by the chain coming off the biggest cog towards the center of
the wheel, if that is possible on your setup. That'll save you some
money and time.
--D-y
someone
> In article <4a886cbe$0$1590$742ec...@news.sonic.net>,
You've been done. If one ferrule can be fitted then all 28/32/36 can
be.
someone
> I just discovered that most of the drive-side spoke holes of one of my rims
> are showing radial cracks.
>
> See:http://tinyurl.com/l8hh5v, and the next five photos in the album.
>
> I have ridden this rim at least a few thousand miles, but during its early
> life the rim would drift out of true. I would discover that one or more
> spokes had gone slack. After truing and evening tension each time as best I
> could the rim would stay in true for only a few hundred miles. The last time
> I trued the rim I increased tension about 3/4 of a turn on all spokes. This
> time the rim has remained true to this day, except now about 1000 miles later
> I see the cracks at the spoke holes.
>
> Questions:
>
> 1) How long before one of these spokes pulls through? The photos show the
> worst of the cracking. Should I stop riding it?
Only if you have excessive spoke tension. When the nipple does pop
throught the rim then a wheel with excessive spoke tension will
buckle, sometimes severley so. Use of appropriate build methods
avoids this.
Tom Sherman °_°
in the mountains. This will result in the rear wheel carrying 65% of the
total weight and not being unweighted over bumps. The "soft" fairing
will result in significantly higher downhill speeds than would be
obtained on a drop-bar road bike.
Having such a bicycle myself, I prefer a rim as least as stout as a Sun
Rhyno Lite and a tire at least 40-mm in width (e.g. Tioga Comp Pool).
Hank
>
> - Show quoted text -
Spocalc lists this rim as a 545 ERD, surprisingly large for the aero
section of the rim. Alex DM18 is also 545mm. The 2.5mm offset spoke
bed of the Ritchey only changes the spoke lengths by a fraction of a
mm, so based on Spocalc and the numbers on alexrims.com, it should be
an easy changeover, with 2 caveats:
1) I make no guarantees to the accuracy of the above numbers (like I
say, 545 seems big for an aero rim); and
2) if the chirality (right- or left-handedness) of the rims are
different, you may wind up with crossed spokes above the valve.
Chalo
>
> Bill Bushnell wrote:
> >
> > I just discovered that most of the drive-side spoke holes of one of
> > my rims are showing radial cracks.
> >
> > See:http://tinyurl.com/l8hh5v, and the next five photos in the
> > album.
> > 2) What replacement rim would you recommend? These are ISO 559 (MTB)
> > rims.
>
> Bill, first off- nice collection of photos of broken bike parts.
> Generally well lit and close enough to show detail. Nice job.
>
> Second, I'd stop riding that rim just because it's obviously already
> unreliable. I'd be inclined to look for an Alex rim (Chalo can
> recommend particulars) or a polished Sun CR18. I have had good results
> with the latter, even though it's only a single-ferruled rim.
If you are cool with using only tires of 1.5" or greater width, then
you should replace with an Alex DM24 rim. There is no stronger rim of
orthodox dimensions, and it is close enough to the same diameter as
the Ritchey rim as to be able to reuse spokes.
If you like tires of less than 35mm actual width, then consider the
Alex DM18, but know that it wants spokes 1mm longer than what you've
got and evaluate accordingly.
Either of these rims represents the best cost/quality ratio in the
industry.
Chalo
Michael Press
Bill Bushnell <mrb...@pobox.com> wrote:
Sun CR18. A bit heavy, but good metal, eyelets, and shiny pretty.
They hold tension.
--
Michael Press
Tom Sherman °_°
provide approximately equal rolling resistance while providing much
better control on loose surfaces and pinch flat resistance.
Chalo
>
> Chalo Colina wrote:
> >
> > If you like tires of less than 35mm actual width, then consider the
> > Alex DM18, but know that it wants spokes 1mm longer than what you've
> > got and evaluate accordingly.
>
> provide approximately equal rolling resistance while providing much
> better control on loose surfaces and pinch flat resistance.
I don't know. It's probably one of those questions like, "why would
anybody want wheels with smaller than 26" inflated diameter?" that
will never be adequately answered.
Chalo
Tom Sherman °_°
overall bicycle size that can not be obtained with large wheels.
Johnny Twelve-Point presented by JFT
> Why would someone want narrower tires that 35-mm?
Not everyone is tall and fat.
someone
Inherent resistance to buckling with low weight and less spokes.
Advantageous for bikes with softer springing over rough hard surfaces.
someone
There is no pre crack bulging and there is no propensity for crack
lines in the rotational direction. It appears that the hole finish
may be partially to blame (along with high spoke tension) for crack
initiation. I would suspect that the thickness of the rim is
sufficient that the addition of washers under the nipple heads
(increasing the nipple support circumference) and twisting the spokes
at their crossings to eliminate bowing (which can only be reduced
otherwise by high spoketension) will be sufficient to give a much
extended mileage than if leaving as is.
Removing the bows in the spokes (bows in spokes may be easily seen if
you make a nipple slack) allows you to operate the wheel with less
spoke tension. The wheel will have a much higher resilience against
buckling and cracking around the nipple holes. Twisting the spokes so
that they kink a little at their crossing also provides a little more
stability due to 'locking' in addition to bow removal. This improves
stability without resort to overtensioning of spokes which leads to
the failures you document.
--D-y
<http://web.ncf.ca/ek867/sander.bike.jpg>
You also forgot women's bikes (to use the term) with 650c wheels.
My wife has a 47cm (c-c) bike with 650's, which (at the very least)
has a much more agreeable feel IRT steering. IOW, it has none of the
"wheel flop" associated with shallow head angles and long rakes seen
on small bikes with 700c wheels, such layout req'd to give toe/front
wheel clearance.
AMuzi
Johnny Twelve-Point presented by JFT wrote:
> Not everyone is tall and fat.
Well, I've been both skinny and fat, but never tall (sigh);
always rode 22mm tubs from 145lb to 210lb and back again.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
RonSonic
>>> Why would someone want narrower tires that 35-mm?
>
>Johnny Twelve-Point presented by JFT wrote:
>> Not everyone is tall and fat.
>
>Well, I've been both skinny and fat, but never tall (sigh);
>always rode 22mm tubs from 145lb to 210lb and back again.
22mm sewups = 25mm clinchers
At least in ride quality and traction and comfort and minimum inflation
pressure. ATMO, YMMV, ETC&
--
Oh damn. There's that annoying blog. Again. http://dumbbikeblog.blogspot.com
Chalo
With my rhetorical question, I was gently ribbing our feet-forward
friend.
I have several bikes with 20" wheels for increased strength or load
capacity or manipulation of frame geometry.
Chalo
jim beam
you're the victim of jobst brandt's not understanding strength of
materials or strength of structures, thus the spokes have been
over-tensioned.
cure is a new rim. replacing with one the same should be fine if built
to the correct spoke tension spec per the rim manufacturer.
while you're at it, write jobst and ask him to pay for this new rim.
it's his ridiculous mistake about spoke tension "as high as the rim can
bear" got you in this mess. as an "expert" charging you for his advice,
he should pay to remedy the problem for making the mistake. and for not
correcting it over three editions of the advice he still sells.
jim beam
says the circus clown who doesn't know anything about design or
materials, and apparently doesn't understand that excess spoke tension
cracked the rim in the first place.
next up: circus clowns, when faced with questions about "why my window
broke when i smashed it with a hammer" apparently wouldn't consider
discarding the hammer, they'd get a thicker window!
someone
Gert Schraner also thought that high tension made better wheels that
"stand", meaning stay true. He qualifies this by rubbishing cheap
rims, being made of poor material, and announces that they cannot bear
the tension 'needed' by his build method. This has been a common
view expressed in this ng recently of which I am in opposition. It is
the build method which needs modifying so that a stable wheel can
"stand" with less tension. He does not even reduce tension for his
tied and soldered wheels, at least he recognises that they do
stabilise the spokes in arduous conditions.
Chalo
>
> next up: circus clowns, when faced with questions about "why my window
> broke when i smashed it with a hammer" apparently wouldn't consider
> discarding the hammer, they'd get a thicker window!
If you could pay 1/4 to 1/2 the price of a direct replacement and get
a window that wouldn't be smashed if you hit it with a hammer (and was
superior in every other respect), you'd be a retarded oblivious
jackass to do otherwise. Like you, for instance.
Chalo
jim beam
wassamatter circus clown? fundamentally not funny - even when tripping
over your own goddamned feet? or too stooopid to understand a simple
analogy? [rhetorical]
Bill Bushnell
> On 18 Aug, 01:02, jim beam <m...@privacy.net> wrote:
> > Bill Bushnell wrote:
> > > I just discovered that most of the drive-side spoke holes of one of my rims
> > > are showing radial cracks.
> >
> > > See:http://tinyurl.com/l8hh5v, and the next five photos in the album.
> >
> > > I have ridden this rim at least a few thousand miles, but during its early
> > > spokes had gone slack. ?After truing and evening tension each time as best I
> > > could the rim would stay in true for only a few hundred miles. ?The last time
> > > I trued the rim I increased tension about 3/4 of a turn on all spokes. ?This
> > > time the rim has remained true to this day, except now about 1000 miles later
> > > I see the cracks at the spoke holes.
> >
> > > Questions:
> >
> > > worst of the cracking. ?Should I stop riding it?
> >
> > > 2) What replacement rim would you recommend? ?These are ISO 559 (MTB) rims.
> >
> > you're the victim of jobst brandt's not understanding strength of
> > materials or strength of structures, thus the spokes have been
> > over-tensioned.
> >
> > to the correct spoke tension spec per the rim manufacturer.
> >
> > while you're at it, write jobst and ask him to pay for this new rim.
> > it's his ridiculous mistake about spoke tension "as high as the rim can
> > he should pay to remedy the problem for making the mistake. ?and for not
> > correcting it over three editions of the advice he still sells.
> Gert Schraner also thought that high tension made better wheels that
> "stand", meaning stay true. He qualifies this by rubbishing cheap
> rims, being made of poor material, and announces that they cannot bear
> the tension 'needed' by his build method. This has been a common
> view expressed in this ng recently of which I am in opposition. It is
> the build method which needs modifying so that a stable wheel can
> "stand" with less tension. He does not even reduce tension for his
> tied and soldered wheels, at least he recognises that they do
> stabilise the spokes in arduous conditions.
Is there a sweet spot of spoke tension between the "over-tensioned" final
state of my wheel that resulted in spoke hole cracks and the 3/4-turn less
tensioned state that might have been under-tensioned, allowing spokes to go
slack? Maybe there is no tension that would both keep spokes tight and not
crack this rim.
I don't understand how allowing spokes to go slack at each revolution, thereby
loading a longer arc of rim is desirable, whether or not spokes are fixed at
their crossings or nipple threads are "prepped" or "locked". Wouldn't this
merely shift the fatigue-cycling from the material about the spoke hole to the
material joining the rim bed to the rim wall?
Many years ago one of my riding companions discovered while on a bike ride
that several spokes on his rear wheel had gone slack putting the rim out of
true. Further examination showed that the rim bed had separated from the rim
walls nearly all the way around the wheel. Unable to repair the wheel on the
road he had to be driven back to the start. (Matrix rim from a nearly new
1993 Trek 520).
The wheel in question sees an unsprung load of up to 200 lbs and is shod with
a 40mm slick tire. I have another wheel that stays true and crack-free under
similar service and is built to similar tension (1/4-tone lower on the
drive-side) with a similar rim (Ritchey OCR Pro). The main difference is that
the "Pro" rim has eyelets on the outer wall and is a slightly lighter rim than
the "Comp".
--
Bill Bushnell
http://pobox.com/~bushnell/
Tom Sherman °_°
Jeffrey has UNIQUE hypotheses on wheel building and how tension spoked
wheels work.
> Many years ago one of my riding companions discovered while on a bike ride
> that several spokes on his rear wheel had gone slack putting the rim out of
> true. Further examination showed that the rim bed had separated from the rim
> walls nearly all the way around the wheel. Unable to repair the wheel on the
> road he had to be driven back to the start. (Matrix rim from a nearly new
> 1993 Trek 520).
>
> The wheel in question sees an unsprung load of up to 200 lbs and is shod with
> a 40mm slick tire. I have another wheel that stays true and crack-free under
> similar service and is built to similar tension (1/4-tone lower on the
> drive-side) with a similar rim (Ritchey OCR Pro). The main difference is that
> the "Pro" rim has eyelets on the outer wall and is a slightly lighter rim than
> the "Comp".
>
Since you are running a sensibly wide tire, as I wrote above, I would
rebuild with a MTB rim such as the Sun Rhyno Lite or Alex DM 24. The
extra strength is worth the 100g or so weight penalty.
jim beam
yes. it's determined by the spoke manufacturer. you should build using
a tensiometer to measure this tension. this "3/4-turn" nonsense is
based on fundamental misunderstandings about structural strength, not
least of which being that strength increases as tension increases - it
doesn't.
> Maybe there is no tension that would both keep spokes tight and not
> crack this rim.
with a highly dished wheel, there may indeed be situations where the nds
spokes go slack. that's why manufacturers, who bother to do their
homework and stayed awake in class, use thread lock! momentarily slack
nds spokes do not compromise wheel strength.
>
> I don't understand how allowing spokes to go slack at each revolution,
if they're doing that, they're too loose. get the spoke tension spec
from the rim manufacturer and use that.
> thereby
> loading a longer arc of rim is desirable, whether or not spokes are fixed at
> their crossings or nipple threads are "prepped" or "locked". Wouldn't this
> merely shift the fatigue-cycling from the material about the spoke hole to the
> material joining the rim bed to the rim wall?
eh?
>
> Many years ago one of my riding companions discovered while on a bike ride
> that several spokes on his rear wheel had gone slack putting the rim out of
> true. Further examination showed that the rim bed had separated from the rim
> walls nearly all the way around the wheel. Unable to repair the wheel on the
> road he had to be driven back to the start. (Matrix rim from a nearly new
> 1993 Trek 520).
ask jobst brandt for a refund for the rim, plus the time and
inconvenience for the repair. that is classic over-tension caused by
his misinformation which has infected pretty much the whole of the
non-engineering cycling repair world, even the late lamented sheldon
brown's pages - the jobstian multi-million dollar mistake.
>
> The wheel in question sees an unsprung load of up to 200 lbs and is shod with
> a 40mm slick tire.
no big deal.
someone
When well built, there are a range of spoke tension that is available
which allows tayloring of a wheels radial stiffness to suit the rider,
frame and conditions. The largest problem I see with wheels, that
neither Brant nor Shraener addresses, is that without specific
attention the spokes, as fitted to a typical flanged hub, will bow
from the rim to the hub. This is effectively adding a soft spring
into the spoke. Only by excess tension, which will crack any well
designed rim, will these 'soft springs' (the bows) be straightened
out. The tension to get them to straighten out leaves no reserve for
the working of the rim. By twisting the spokes around each other at
the crossing before tensioning up, the bows are removed. Excess spoke
tension is then not required to straighten the spokes. This leaves
the builder with the opportunity to use spoke tension of a wide range
depending on rider preference. Using 36x14swg spokes on a stiff, flat
top medium depth sprint rim, I chose to use tension which would be
approaching the minimum to maintain spoke tension during hard
cornering. The spoke tension is around 170lbf . This is much easier
to deal with for building and the kinking of the spokes stabilizes
what would otherwise be.
>
> I don't understand how allowing spokes to go slack at each revolution, thereby
> loading a longer arc of rim is desirable, whether or not spokes are fixed at
> their crossings or nipple threads are "prepped" or "locked". Wouldn't this
> merely shift the fatigue-cycling from the material about the spoke hole to the
> material joining the rim bed to the rim wall?
Within the typical bicycle wheel, the whole rim is loaded. At the
bottom are bending loads, around 5/6 or so are compressive loads which
encourage the rim to spread. The spokes are there to resist this
spread. This is why it is important to remove the bows in the spokes,
the 'softer' spoke cannot resist the spread of the rim so well if
there are bows in it. I do not expect spoke tension to be such that
they go slack and rattle. I expect the spoke to significantly drop in
tension, otherwise, I believe the construction is not at its optimum.
I have used wheels built like this in excess of 40,000 miles without
rim cracking or spoke breaking. They are very comfortable wheels to
ride over rough ground and through high speed corners. Reducing spoke
tension in general will reduce rim loading. Removing the spoke bows
before tensioning means spokes do not go slack despite building with
lower spokwe tension.
>
> Many years ago one of my riding companions discovered while on a bike ride
> that several spokes on his rear wheel had gone slack putting the rim out of
> true. Further examination showed that the rim bed had separated from the rim
> walls nearly all the way around the wheel. Unable to repair the wheel on the
> road he had to be driven back to the start. (Matrix rim from a nearly new
> 1993 Trek 520).
The separation of the rim bed would be due to excessive spoke
tension. Build as I say and spoke tension need not be excessive.
>
> The wheel in question sees an unsprung load of up to 200 lbs and is shod with
> a 40mm slick tire. I have another wheel that stays true and crack-free under
> similar service and is built to similar tension (1/4-tone lower on the
> drive-side) with a similar rim (Ritchey OCR Pro). The main difference is that
> the "Pro" rim has eyelets on the outer wall and is a slightly lighter rim than
> the "Comp".
With an unsprung load then the importance of controlled suspension
within the wheel becomes foremost on the agenda. I tend to use a bike
frame with pencil stays and a suspended leather saddle on a steel
frame. This leaves less work for the wheels and tyres. I have run a
tubular tyre at around 30psi (23mm section front), this is magic
carpet territory.
someone
wrote:
>
> You have to understand that "someone" aka "Nick L Plate" aka Trevor
> Jeffrey has UNIQUE hypotheses on wheel building and how tension spoked
> wheels work.
Walk down the street with a blindfold on and you will bump into
lamposts no matter how bright they shine.
landotter
I'd just write it off as a junk rim. Get something with eyelets next
time. Start with 100kgf drive side, and add a little tension if it
doesn't stay true. That should work with just about any rim.
someone
Adding spoke tension is the worst way to attempt to stabilize a
wheel. Stainless spokes in particular do not wish to form elbows at
the woven crossing point and so the spokes can easily slide across
each other. manually kinking the spokes here will stabilize the
wheel. Excessive tension becomes redundant, the wheel is stable at
lower spoke tensiomn.
jim beam
shut up trevor - you're spewing even more nonsense than jobst, and he
doesn't know shit.
landotter
Moe Ron, is that you?
someone
40,000+ miles rear wheel, no rim cracking, no spokes breaking, 170lbf
14swg . It works, well.
russell...@yahoo.com
I have a wheel in my truing stand that has the spokes completely loose
ready to be trued. If we take your comment above as true, ha ha, then
the wheel should be perfectly ridable as is. Its as strong as it can
get with no tension on the spokes.
Stainless spokes in particular do not wish to form elbows at
> the woven crossing point and so the spokes can easily slide across
> each other. manually kinking the spokes here will stabilize the
> wheel.
Assuming this manually kinking concept is valid, ha ha, how would you
do this to a spoke that is already tensioned on a wheel? After
tensioning the spokes using Mr. Brandt's methods discussed in his
book, and stress relieving as described by Mr. Brandt by grabbing a
pair or spokes and squeezing them, the spokes don't ever change
shape. No bending of the spokes where they cross ever occurs. The
spokes are too highly tensioned and straight to get a kink as you
describe. How are you going to do this manual kinking? Are you going
to put a bend into the spokes before you lace them into the wheel?
Excessive tension becomes redundant, the wheel is stable at
> lower spoke tensiomn.- Hide quoted text -
You and whiskey boy make quite a pair. I usually disregard your and
whiskey boy's posts but occasionally glance at them. Just to
reinforce why I disregard them.
>
> - Show quoted text -
someone
<russellseat...@yahoo.com> wrote:
> > Adding spoke tension is the worst way to attempt to stabilize a
> > wheel.
>
> I have a wheel in my truing stand that has the spokes completely loose
> ready to be trued. If we take your comment above as true, ha ha, then
> the wheel should be perfectly ridable as is. Its as strong as it can
> get with no tension on the spokes.
No. You are showing your ignorance. The slack must be taken out of
the spokes, otherwise it is not a tension wheel, but a collection of
connected elements.
>
> Stainless spokes in particular do not wish to form elbows at
>
> > the woven crossing point and so the spokes can easily slide across
> > each other. manually kinking the spokes here will stabilize the
> > wheel.
>
> Assuming this manually kinking concept is valid, ha ha, how would you
> do this to a spoke that is already tensioned on a wheel?
Assuming the spokes were not already excessively tensioned, the
simplest method without resorting to custom pliers is to use two
levers pushing towards the crossing and twisting. Thin flat cone
spanners work well and are standard wheel tools.
> After
> tensioning the spokes using Mr. Brandt's methods discussed in his
> book, and stress relieving as described by Mr. Brandt by grabbing a
> pair or spokes and squeezing them, the spokes don't ever change
> shape.
They will if you squeeze hard enough. The results are not predictable
enough. and include undesirable reverse bows.
> No bending of the spokes where they cross ever occurs.
They will if you squeeze hard enough.
> The spokes are too highly tensioned
Agreed.
> and straight to get a kink as you
> describe. How are you going to do this manual kinking? Are you going
> to put a bend into the spokes before you lace them into the wheel?
See above. I have used a jig to pre-bend the spokes but it just seems
like another additional process where doing it with the spokes in
place and the nipples snug is more satisfying because the wheel is
almost finished.
>
> Excessive tension becomes redundant, the wheel is stable at
>
> > lower spoke tensiomn.- Hide quoted text -
>
> You and whiskey boy make quite a pair. I usually disregard your and
> whiskey boy's posts but occasionally glance at them. Just to
> reinforce why I disregard them.
Blindfolds and lamposts.
Bill Bushnell
> When well built, there are a range of spoke tension that is available
> which allows tayloring of a wheels radial stiffness to suit the rider,
> frame and conditions. The largest problem I see with wheels, that
> neither Brant nor Shraener addresses, is that without specific
> attention the spokes, as fitted to a typical flanged hub, will bow
> from the rim to the hub. This is effectively adding a soft spring
> into the spoke. Only by excess tension, which will crack any well
> designed rim, will these 'soft springs' (the bows) be straightened
> out. The tension to get them to straighten out leaves no reserve for
> the working of the rim. By twisting the spokes around each other at
> the crossing before tensioning up, the bows are removed. Excess spoke
> tension is then not required to straighten the spokes. This leaves
> the builder with the opportunity to use spoke tension of a wide range
> depending on rider preference. Using 36x14swg spokes on a stiff, flat
> top medium depth sprint rim, I chose to use tension which would be
> approaching the minimum to maintain spoke tension during hard
> cornering. The spoke tension is around 170lbf . This is much easier
> to deal with for building and the kinking of the spokes stabilizes
> what would otherwise be.
Can you direct us to any photos of wheels built with your "soft spring" spokes?
Bill Bushnell
> if they're doing that, they're too loose. get the spoke tension spec
> from the rim manufacturer and use that.
Although this information might be useful, I've never seen spoke tension specs
from rim manufacturers available either in literature or on-line. Is there a
database somewhere with this information?
someone
They don't appear any different from an overstrung wheel. Only when
spoke tension is released and the spokes are observed does it become
obvious of the difference. The spokes on my wheels stay where they
are and with a wheel with non-modified spokes they will bow. These
changes are obvious to the eye without resorting to a straight edge.
A straight edge may be used on a loaded wheel to check lower spokes
and their deviation.
AMuzi
Bill Bushnell wrote:
> Can you direct us to any photos of wheels built with your "soft spring" spokes?
this maybe?
http://www.gsportbmx.com/images/georgesguides/wheel21.jpg
Ben C
[...]
> Is there a sweet spot of spoke tension between the "over-tensioned" final
> state of my wheel that resulted in spoke hole cracks and the 3/4-turn less
> tensioned state that might have been under-tensioned, allowing spokes to go
> slack? Maybe there is no tension that would both keep spokes tight and not
> crack this rim.
>
> I don't understand how allowing spokes to go slack at each revolution, thereby
> loading a longer arc of rim is desirable, whether or not spokes are fixed at
> their crossings or nipple threads are "prepped" or "locked".
If they're going slack on _every_ revolution then they are definitely
too loose. But they only need to go slack occasionally (you hit a bump
or something now and again) for the wheel to go out of true. So linseed
or other threadlock is a practical solution.
someone
Now that's what I'm on about. That is what you want to avoid in a non
trick rim for efficiency and durability with fewer spokes.
Of fewer spokes I suspect that I (180lb) can manage on a rear 28
spoke cross three of 16swg on a 300g sprint when both crossings are
tied and soldered.
Frank Krygowski
> On 18 Aug, 15:28, "russellseat...@yahoo.com"
>
>
> > tensioning the spokes using Mr. Brandt's methods discussed in his
> > book, and stress relieving as described by Mr. Brandt by grabbing a
> > pair or spokes and squeezing them, the spokes don't ever change
> > shape.
>
> They will if you squeeze hard enough. The results are not predictable
> enough. and include undesirable reverse bows.
>
> > No bending of the spokes where they cross ever occurs.
>
> They will if you squeeze hard enough.
Hold on. On my touring bike, I did at least 20,000 miles on 27" rims
before I switched to 700c. When I disassembled those wheels to re-use
the hubs, the spokes were still straight, no kinks.
The only broken spoke on that bike happened after a friend briefly
borrowed it, fell in loose sand, and stepped on the rear wheel.
Are you saying my spokes should have broken? Or are you saying they
should have been bent at the crosses? Neither seems to be true to me.
- Frank Krygowski
Bill Bushnell
> this maybe?
> http://www.gsportbmx.com/images/georgesguides/wheel21.jpg
I think this photo shows the effect better:
http://www.gsportbmx.com/images/georgesguides/wheel28.jpg
There are other photos, starting with ../wheel1.jpg to ../wheel28.jpg.
I don't see how these spokes are any different from those on a larger wheel
using a 3x pattern. The small wheel, thick spokes, 4-cross pattern, and 48
spoke count merely exaggerate the bending path each spoke takes.
Bill Bushnell
If I use thread lock on the nipples, how would I know that the spokes are
going slack only occasionally and not every revolution? How many times can
the spokes alternate from slack to taut before something else fails? Must
I avoid riding bumpy roads or carrying extra weight?
Isn't using thread lock on nipples like treating a symptom rather than a
cause?
jim beam
> jim beam <m...@privacy.net> wrote:
>> if they're doing that, they're too loose. get the spoke tension spec
>> from the rim manufacturer and use that.
>
> Although this information might be useful, I've never seen spoke tension specs
> from rim manufacturers available either in literature or on-line. Is there a
> database somewhere with this information?
>
they've been posted here before many times. google is your friend.
also park tool has some as part of the info for their tensiometer.
failing that, you can always call the manufacturer.
jim beam
don't taunt the poor boy - reality is cruel enough.
jim beam
only if you believe the fud of the ignorati.
bottom line - the only "damage" caused by slack spokes is the
opportunity for the spoke nipples to unscrew. thread lock prevents
this. and there exists great evidence as to efficacy - competent
manufacturers who have significant research budgets actually use it,
despite the fact that doing so marginally reduces their profit margin!
someone
Which is precisely what you need to avoid (with lower spoke counts and
a larger rim) for efficiency and durability with a regular bicycle
wheel.
someone
The kinks do occur naturally, to a lesser extent than manipulation
during the build, after considerable mileage with carbon steel spokes
but not it seems wih stainless spokes to any obvious extent (including
overtensioning of spokes for worthless stress relief). The lateral
stability of a wheel when it supports its maximum load is the most
telling difference between wheels which have had their bows eliminated
to those which have not.
someone
> If I use thread lock on the nipples, how would I know that the spokes are
> going slack only occasionally and not every revolution? How many times can
> the spokes alternate from slack to taut before something else fails? Must
> I avoid riding bumpy roads or carrying extra weight?
>
> Isn't using thread lock on nipples like treating a symptom rather than a
> cause?
>
Apply a test load to the wheel equating to the maximum steady load,
like when braking a front wheel or cornering on a rear wheel. I tend
to use twice the body weight but may go a little higher or lower than
this depending on components and use. Using threadlock is perfectly
valid application in vibratory systems on metal screws when other
mechanical devices cannot be used due to size, weight or economic
restrictions. You cannot expect smooth roads so there will be
vibrations. The road undulations causing vibrations also displace the
rim at the bottom of the wheel upwards and the bottom spoke's span is
reduced so lowering its tension allowing the vibration to unscrew the
nipple a smidgen.
Frank Krygowski
Hmm. And yet, with no attempt to eliminate bows, my wheels have had
perfect lateral stability. That is, I've never once tacoed a wheel.
Perfect is good enough for me.
- Frank Krygowski
someone
A rather specific definition for lateral stability. Have you actually
tested your wheels for lateral stability with a suitable radial load,
or not? I take it that you have taken a nipple key to your wheels
to correct lateral deviation.
andre...@aol.com
Mavic posts this info but not in their consumer pages. They publish it
in the manual directed to distributors and they ask for name and
password that has been given in this group. don't know is other rim
makers disseminate this info. It is as if they know that this info is
important but they will not volunteer it automatically.
DT swiss makes rims that seems to tolerate a good amount of tension.
Bill Bushnell
> On 19 Aug, 04:25, Bill Bushnell <mrb...@pobox.com> wrote:
> > I think this photo shows the effect better:
> >
> > http://www.gsportbmx.com/images/georgesguides/wheel28.jpg
> >
> > There are other photos, starting with ../wheel1.jpg to ../wheel28.jpg.
> >
> > I don't see how these spokes are any different from those on a larger wheel
> > spoke count merely exaggerate the bending path each spoke takes.
> >
> Which is precisely what you need to avoid (with lower spoke counts and
> a larger rim) for efficiency and durability with a regular bicycle
> wheel.
The only wheel that avoids all spoke bowing at spoke crossings is one that is
spoked radially. Are you saying that radially-spoked wheels are more durable than
cross-spoked wheels?
And, what do you mean by "efficiency"?
someone
Radial spoked wheels cannot have the spokes braced against each other
so without a ring to tie the spokes to, then no they are not as robust
as a tangential spoked wheel built to my standard.
Less energy to build, less unresolved energy storage. Proficiency in
its ability to be used as a bicycle wheel in all conditions without
risk of injurous failure. Energy efficient in use, the wheel tracks
accurately when cornering hard or climbing out of the saddle, climbing
rate differences are pronounced with steepening grades. The more the
wheel is loaded the greater the benefit over a wheel constructed
without spoke manipulation at the crossings.
Jobst Brandt
>>> if they're doing that, they're too loose. get the spoke tension spec
>> Although this information might be useful, I've never seen spoke
>> tension specs from rim manufacturers available either in literature
>> or on-line. Is there a database somewhere with this information?
> Mavic posts this info but not in their consumer pages. They publish
> it in the manual directed to distributors and they ask for name and
> password that has been given in this group. don't know is other rim
> makers disseminate this info. It is as if they know that this info
> is important but they will not volunteer it automatically.
> DT swiss makes rims that seems to tolerate a good amount of tension.
I suspect that rim manufacturers rather not tell people that their
rims cannot support commonly used spoke tension because it makes them
look weak. As contributors to spoke cracking and spoke tension
threads have mentioned, if spokes do not require tension to make a
strong wheel, why tighten them more than taking out slack?
I find odd that readily apparent that all spoked wheels support loads
by compressing the bottom spokes. To keep thin wire spokes from
buckling under loads, they must be pre-tensioned so that the algebraic
sum of compression and pre-tension does not go to zero. That means
that spoke tension must be high enough to prevent slack spokes from
which the wheel is incomplete, slack spokes are no longer part of the
structure being as good as removed from the wheel. Neither wooden
wagon wheels nor wire spoked bicycle wheels hang from the top spokes.
As I have often mentioned, spoke tension can be assessed by the tone
emitted when plucked (near the spoke nipple), and that tone remains
unchanged for the top spokes when a wheel is vertically loaded and
unloaded. In contrast bottom spokes change their tone greatly under
the same loading test.
Jobst Brandt
Michael Press
Bill Bushnell <mrb...@pobox.com> wrote:
> If I use thread lock on the nipples, how would I know that the spokes are
> going slack only occasionally and not every revolution? How many times can
> the spokes alternate from slack to taut before something else fails? Must
> I avoid riding bumpy roads or carrying extra weight?
>
> Isn't using thread lock on nipples like treating a symptom rather than a
> cause?
Yes.
--
Michael Press
jim beam
> Andres Muro wrote:
>
>>>> if they're doing that, they're too loose. get the spoke tension spec
>
>>> Although this information might be useful, I've never seen spoke
>>> tension specs from rim manufacturers available either in literature
>>> or on-line. Is there a database somewhere with this information?
>
>> Mavic posts this info but not in their consumer pages. They publish
>> it in the manual directed to distributors and they ask for name and
>> password that has been given in this group. don't know is other rim
>> makers disseminate this info. It is as if they know that this info
>> is important but they will not volunteer it automatically.
>
>> DT swiss makes rims that seems to tolerate a good amount of tension.
>
> I suspect that rim manufacturers rather not tell people that their
> rims cannot support commonly used spoke tension because it makes them
> look weak.
weak??? how can tension define strength jobst? either static or
fatigue? do you even have the slightest clue what the fuck you're
talking about?
> As contributors to spoke cracking and spoke tension
> threads have mentioned, if spokes do not require tension to make a
> strong wheel, why tighten them more than taking out slack?
why indeed? you /do/ know that a load calculation is not a strength
calculation don't you jobst?
>
> I find odd that readily apparent that all spoked wheels support loads
> by compressing the bottom spokes.
er, what you're actually observing jobst is distribution as a function
of rim distortion. if the rim were infinitely stiff, the load would be
more evenly distributed.
> To keep thin wire spokes from
> buckling under loads, they must be pre-tensioned so that the algebraic
> sum of compression and pre-tension does not go to zero.
why? clue: strength is not a function of tension for materials with
equal tensile and compressive strengths - like aluminum box section.
you /do/ understand structural principles don't you jobst?
> That means
> that spoke tension must be high enough to prevent slack spokes from
> which the wheel is incomplete, slack spokes are no longer part of the
> structure being as good as removed from the wheel. Neither wooden
> wagon wheels nor wire spoked bicycle wheels hang from the top spokes.
see above jobst - you have a fundamental misconception about what you're
observing with tension distribution.
>
> As I have often mentioned, spoke tension can be assessed by the tone
> emitted when plucked (near the spoke nipple), and that tone remains
> unchanged for the top spokes when a wheel is vertically loaded and
> unloaded. In contrast bottom spokes change their tone greatly under
> the same loading test.
see above jobst. you're propagating fundamental misconceptions because
of your own painful ignorance.
jim beam
except that unless you have a massively stiff rim, or an undished wheel,
you can't achieve that ideal. thus, real world engineers that observe
reality, not try to force facts to fit theory, use threadlock.
Tom Sherman °_°
> Jobst Brandt wrote:
>> Andres Muro wrote:
>>
>>>>> if they're doing that, they're too loose. get the spoke tension spec
>>
>>>> Although this information might be useful, I've never seen spoke
>>>> tension specs from rim manufacturers available either in literature
>>>> or on-line. Is there a database somewhere with this information?
>>
>>> Mavic posts this info but not in their consumer pages. They publish
>>> it in the manual directed to distributors and they ask for name and
>>> password that has been given in this group. don't know is other rim
>>> makers disseminate this info. It is as if they know that this info
>>> is important but they will not volunteer it automatically.
>>
>>> DT swiss makes rims that seems to tolerate a good amount of tension.
>>
>> I suspect that rim manufacturers rather not tell people that their
>> rims cannot support commonly used spoke tension because it makes them
>> look weak.
>
> weak??? how can tension define strength jobst? either static or
> fatigue? do you even have the slightest clue what the fuck you're
> talking about?
>
would realize that your reply is nonsensical in that it assumes that
Jobst wrote things that he did not.
To translate, if a rim manufacturer lists a maximum spoke tension less
than that of the competition, the consumer will get the impression that
the wheel with the lower maximum allowable spoke tension is weaker.
This really should not be so hard.
>
>> As contributors to spoke cracking and spoke tension
>> threads have mentioned, if spokes do not require tension to make a
>> strong wheel, why tighten them more than taking out slack?
>
> why indeed? you /do/ know that a load calculation is not a strength
> calculation don't you jobst?
>
Non sequitur.
>
>>
>> I find odd that readily apparent that all spoked wheels support loads
>> by compressing the bottom spokes.
>
> er, what you're actually observing jobst is distribution as a function
> of rim distortion. if the rim were infinitely stiff, the load would be
> more evenly distributed.
>
Where can I buy some of these infinitely stiff rims?
>
>> To keep thin wire spokes from
>> buckling under loads, they must be pre-tensioned so that the algebraic
>> sum of compression and pre-tension does not go to zero.
>
> why? clue: strength is not a function of tension for materials with
> equal tensile and compressive strengths - like aluminum box section. you
> /do/ understand structural principles don't you jobst?
>
Again, non sequitur to what Jobst wrote.
>
>> That means
>> that spoke tension must be high enough to prevent slack spokes from
>> which the wheel is incomplete, slack spokes are no longer part of the
>> structure being as good as removed from the wheel. Neither wooden
>> wagon wheels nor wire spoked bicycle wheels hang from the top spokes.
>
> see above jobst - you have a fundamental misconception about what you're
> observing with tension distribution.
>
How is a spoke that would lift the nipple away from the rim but for the
rim strip contributing to the strength of the wheel? A wheel that is
being ridden, not one in a static loading condition.
>
>>
>> As I have often mentioned, spoke tension can be assessed by the tone
>> emitted when plucked (near the spoke nipple), and that tone remains
>> unchanged for the top spokes when a wheel is vertically loaded and
>> unloaded. In contrast bottom spokes change their tone greatly under
>> the same loading test.
>
> see above jobst. you're propagating fundamental misconceptions because
> of your own painful ignorance.
>
Why do the FEA analysis and spoke tension measurements of others agree
with Jobst then? Several examples have been posted to the group in the past.
--
Tom Sherman - 42.435731,-83.985007
Celebrity culture is an opposite of community, informing us
that these few nonsense-heads matter but that the rest of
us do not. - Jay Griffiths
Tom Sherman °_°
A stiff rear rim (e.g. Sun Rhyno Lite or Alex DM 24) is exactly what is
called for on the OP's bicycle.
RonSonic
Thanks Tom. You saved me some typing and the use of language I'd regret.
--
Oh damn. There's that annoying blog. Again. http://dumbbikeblog.blogspot.com
someone
>
> I find odd that readily apparent that all spoked wheels support loads
> by compressing the bottom spokes. To keep thin wire spokes from
> buckling under loads,
Hold it. Wire spokes can only take their load under tension. They
are not beams or columns which may buckle with compression. The rim
is an arched beam and will buckle with excessive compressive force.
Much of this buckling force comes from over tensioned spokes. Wire
spokes never buckle because of the wheel construction fails to allow
it. KIPPERS brandt.
> structure being as good as removed from the wheel. Neither wooden
> wagon wheels nor wire spoked bicycle wheels hang from the top spokes.
The wheel stands on the ground. It holds up the frame which supports
the rider and permits him to proceed with minimal effort due to his
weight being supported by the frame and the wheels. This is why the
bicycle exists.
>
> As I have often mentioned, spoke tension can be assessed by the tone
> emitted when plucked (near the spoke nipple), and that tone remains
> unchanged
Wrong again. Not with a well constructed wheel, the increase in pitch
is clear and is measured with an electronic musical instrument tuner
for those who are tone deaf.
for the top spokes when a wheel is vertically loaded and
> unloaded. In contrast bottom spokes change their tone greatly under
> the same loading test.
Because they are irrelevant, their tension is reduced because the rim
is displaced by the load.
RonSonic
Google sez: Results 1 - 10 of about 1,490 for jobst group:rec.bicycles.tech
author:jim author:beam
jim beam
how???? you're not thinking, let alone explaining!
>
> This really should not be so hard.
but apparently it is!
dude, again, /think/. that "fea" is a load calculation, not a strength
calculation. replication doesn't change that.
bottom line: load does not determine strength. it seems the
understanding of fundamentals is a /real/ problem!
someone
wrote:
> To translate, if a rim manufacturer lists a maximum spoke tension less
> than that of the competition, the consumer will get the impression that
> the wheel with the lower maximum allowable spoke tension is weaker.
>
> This really should not be so hard.
>
Lay off the porn sites.
>
> >> I find odd that readily apparent that all spoked wheels support loads
> >> by compressing the bottom spokes.
>
> > er, what you're actually observing jobst is distribution as a function
> > of rim distortion. if the rim were infinitely stiff, the load would be
> > more evenly distributed.
>
> Where can I buy some of these infinitely stiff rims?
You cannot buy them for all the tea in China. They are way too
expensive. Do a pact with Lucifer and you still wont pay for them.
>
> >> To keep thin wire spokes from
> >
>
>
> >> That means
> >> that spoke tension must be high enough to prevent slack spokes from
> >> which the wheel is incomplete, slack spokes are no longer part of the
> >> structure being as good as removed from the wheel. Neither wooden
> >> wagon wheels nor wire spoked bicycle wheels hang from the top spokes.
>
> > see above jobst - you have a fundamental misconception about what you're
> > observing with tension distribution.
>
> How is a spoke that would lift the nipple away from the rim but for the
> rim strip contributing to the strength of the wheel? A wheel that is
> being ridden, not one in a static loading condition.
>
> Why do the FEA analysis and spoke tension measurements of others agree
> with Jobst then? Several examples have been posted to the group in the past.
Because they all ignore the variation in rim compression?
Bill Bushnell
> On 19 Aug, 21:57, Bill Bushnell <mrb...@pobox.com> wrote:
> > someone <thirty-...@live.co.uk> wrote:
> > > On 19 Aug, 04:25, Bill Bushnell <mrb...@pobox.com> wrote:
> > > > I think this photo shows the effect better:
> >
> > > >http://www.gsportbmx.com/images/georgesguides/wheel28.jpg
> >
> > > > There are other photos, starting with ../wheel1.jpg to ../wheel28.jpg.
> >
> > > > I don't see how these spokes are any different from those on a larger wheel
> > > > using a 3x pattern. ?The small wheel, thick spokes, 4-cross pattern, and 48
> > > > spoke count merely exaggerate the bending path each spoke takes.
> >
> > > Which is precisely what you need to avoid (with lower spoke counts and
> > > a larger rim) for efficiency and durability with a regular bicycle
> > > wheel.
> >
> > The only wheel that avoids all spoke bowing at spoke crossings is one that is
> > cross-spoked wheels?
> >
> > And, what do you mean by "efficiency"?
> Radial spoked wheels cannot have the spokes braced against each other
> so without a ring to tie the spokes to, then no they are not as robust
> as a tangential spoked wheel built to my standard.
Then, why do you say above that one should avoid a bending spoke path of the
kind shown in the photo above? Are you advocating that spokes pass through
each other at crossings, assuming that were possible?
Do you know of any online photos of wheels "built to your standard"? I can't
envision what you're advocating.
> Less energy to build, less unresolved energy storage. Proficiency in
> its ability to be used as a bicycle wheel in all conditions without
> risk of injurous failure. Energy efficient in use, the wheel tracks
> accurately when cornering hard or climbing out of the saddle, climbing
> rate differences are pronounced with steepening grades. The more the
> wheel is loaded the greater the benefit over a wheel constructed
> without spoke manipulation at the crossings.
Can we agree that a good wheel acts as a rigid unit under normal service? If
so, how is energy lost? What mechanism generates the heat?
jim beam
> "jim beam" wrote:
>> Michael Press wrote:
>>> In article <4a8b73ca$0$1594$742e...@news.sonic.net>,
>>> Bill Bushnell <mrb...@pobox.com> wrote:
>>>
>>>> If I use thread lock on the nipples, how would I know that the
>>>> spokes are
>>>> going slack only occasionally and not every revolution? How many
>>>> times can
>>>> the spokes alternate from slack to taut before something else
>>>> fails? Must
>>>> I avoid riding bumpy roads or carrying extra weight?
>>>>
>>>> Isn't using thread lock on nipples like treating a symptom rather
>>>> than a
>>>> cause?
>>>
>>> Yes.
>>>
>>
>> except that unless you have a massively stiff rim, or an undished
>> wheel, you can't achieve that ideal. thus, real world engineers that
>> observe reality, not try to force facts to fit theory, use threadlock.
>
> A stiff rear rim (e.g. Sun Rhyno Lite or Alex DM 24) is exactly what is
> called for on the OP's bicycle.
>
and a wheel with no dish...
jim beam
tell you what ron - /you/ hammer some engineering into jobst's thick
head and this nonsense can stop. start with his recent howler, "brake
cables do not stretch elastically in use".
RonSonic
Nobody who sells retail wants to have a lower published number associated with
his product than the other guy.
>> This really should not be so hard.
>
>but apparently it is!
Yeah, apparently it is.
--
Frank Krygowski
?? I've ridden wheels for tens of thousands of miles, on and off
road, with and without loads on the bike, over smooth roads and rough
ones. The wheels have worked excellently. I true them very rarely,
and break spokes less often than that. What more do I need?
- Frank Krygowsk
Tom Sherman °_°
Indeed, "jim" is so blinded by hate of Jobst that he reads what he wants
to read, not what is written.
Tom Sherman °_°
>> Less energy to build, less unresolved energy storage. Proficiency in
>> its ability to be used as a bicycle wheel in all conditions without
>> risk of injurous failure. Energy efficient in use, the wheel tracks
>> accurately when cornering hard or climbing out of the saddle, climbing
>> rate differences are pronounced with steepening grades. The more the
>> wheel is loaded the greater the benefit over a wheel constructed
>> without spoke manipulation at the crossings.
>
> Can we agree that a good wheel acts as a rigid unit under normal service? If
> so, how is energy lost? What mechanism generates the heat?
>
Trevor is the source of hot air on this subject.
RonSonic
Two thoughts on that; first, you aren't hammering anything except the keyboard
because Jobst's head remains completely unaffected.
Second I'm not sure they do to any meaningful extent. Rubber brake blocks,
aluminum levers and caliper arms all flex so much more that this isn't something
I can feel. I don't know that the housing doesn't collapse as much as the cable
elongates and I'm pretty damn sure some portion of that will be the strands
trying to straighten themselves. Except for cables that have undergone some
severe drawing or rolling process there's going to be some constriction as they
bundle themselves tighter as well. So we've got a few mechanisms for elongation
that don't require elastic stretching and so much other stuff bending and
compressing, I'm not sure. I've got a lot of experience with music wire, but
it's not the same stuff despite the nickel steel content.
No doubt some stretching occurs just as it does when you drive one car over a
suspension bridge. Don't know that it makes a difference or that this stretching
is permanent.
Now we can analyze the hell out of it. We could Fogel lab the thing. Calling
each other names hasn't resulted in any insight.
jim beam
eh??? answer this /real/ simple question tom - you are an engineer
afterall:
a tensile sample is unloaded from 1000Nf to 400Nf. how strong is the
sample?
jim beam
dude, did you not read this thread? did you not see the math? was it
not /real/ simple? was it not ridiculous that an "engineer", after 50
years of bleating nonsense on that topic, had never bothered to do it?
> just as it does when you drive one car over a
> suspension bridge. Don't know that it makes a difference or that this stretching
> is permanent.
>
> Now we can analyze the hell out of it.
how about we /read/ the hell out of it instead???
someone
> someone <thirty-...@live.co.uk> wrote:
> > On 19 Aug, 21:57, Bill Bushnell <mrb...@pobox.com> wrote:
> > > someone <thirty-...@live.co.uk> wrote:
> > > > On 19 Aug, 04:25, Bill Bushnell <mrb...@pobox.com> wrote:
> > > > > I think this photo shows the effect better:
>
> > > > >http://www.gsportbmx.com/images/georgesguides/wheel28.jpg
>
> > > > > There are other photos, starting with ../wheel1.jpg to ../wheel28.jpg.
>
> > > > > I don't see how these spokes are any different from those on a larger wheel
> > > > > using a 3x pattern. ?The small wheel, thick spokes, 4-cross pattern, and 48
> > > > > spoke count merely exaggerate the bending path each spoke takes.
>
> > > > Which is precisely what you need to avoid (with lower spoke counts and
> > > > a larger rim) for efficiency and durability with a regular bicycle
> > > > wheel.
>
> > > The only wheel that avoids all spoke bowing at spoke crossings is one that is
> > > spoked radially. ?Are you saying that radially-spoked wheels are more durable than
> > > cross-spoked wheels?
>
> > > And, what do you mean by "efficiency"?
> > Radial spoked wheels cannot have the spokes braced against each other
> > so without a ring to tie the spokes to, then no they are not as robust
> > as a tangential spoked wheel built to my standard.
>
> Then, why do you say above that one should avoid a bending spoke path of the
> kind shown in the photo above? Are you advocating that spokes pass through
> each other at crossings, assuming that were possible?
It's not possible. But you've got me thinking on this on
different ways of connecting the bearing to the lightweight peripheral
rim. Ezekiel's vision again comes to mind, I'm thinking of a way of
reducing the mass of tensile elements nearest the bearing so reducing
the overall mass of the lightest wheels, still using steel for its
reliability and cost advantage.
The lateral displacement of the spokes at the crossing does nothing
to enhance the wheel construction. The displacement by the radius of
the spoke is a very minor concern when the bracing is some thirty
times this. Making sure that all crossings are in the same plane is
valuable in leaving a stable wheel if the crossings are not tied and
soldered.
> Do you know of any online photos of wheels "built to your standard"? I can't
> envision what you're advocating.
I've said it before, you wont see the difference in a completed wheel
with the naked eye over an overstrung wheel with a deep rim. Using
soft spokes makes the forming much easier and cheaper.
>
> > Less energy to build, less unresolved energy storage. Proficiency in
> > its ability to be used as a bicycle wheel in all conditions without
> > risk of injurous failure. Energy efficient in use, the wheel tracks
> > accurately when cornering hard or climbing out of the saddle, climbing
> > rate differences are pronounced with steepening grades. The more the
> > wheel is loaded the greater the benefit over a wheel constructed
> > without spoke manipulation at the crossings.
>
> Can we agree that a good wheel acts as a rigid unit under normal service? If
> so, how is energy lost? What mechanism generates the heat?
A good wheel needs to have an element of give. This must be
controlled within the tyre and the rest of the wheel. The rim/spoke
assembly should not be overly rigid (neither should the tyre, hence
pnuematics) because wheel replacement is usually quicker and cheaper
than frame repair (if possible).
Distortion of material causes hysteresis losses in the metal wheel
components and its tyre.
someone
An argument.
someone
> On Wed, 19 Aug 2009 21:07:26 -0700, jim beam <m...@privacy.net> wrote:
> >RonSonic wrote:
> >> On Wed, 19 Aug 2009 19:34:08 -0700, jim beam <m...@privacy.net> wrote:
>
> >>> Michael Press wrote:
Measure the compression of the housing and the extension of the inner
wire with a full pull on a lever.
RonSonic
No, jim I didn't.
>did you not see the math? was it
>not /real/ simple? was it not ridiculous that an "engineer", after 50
>years of bleating nonsense on that topic, had never bothered to do it?
No. Because elastic elongation is insignificant in practice.
>> just as it does when you drive one car over a
>> suspension bridge. Don't know that it makes a difference or that this stretching
>> is permanent.
>>
>> Now we can analyze the hell out of it.
>
>how about we /read/ the hell out of it instead???
Don't care to. Most of your stuff is so dedicated to trying to prove JB wrong
somehow that it becomes uninteresting to someone who doesn't share that
particular passion. Am I missing something useful? Perhaps. If the subject of
cable stretch ever introduced itself to my curiousity I'd satisfy it with
reference to a cable manufacturer's chart and some numbers scribbled on a stray
piece of paper for the quick version. Or I'd go empirical and mount a bass
tuning key to a railroad tie and stretch one with a few doodads added for
meauring cable stretch and all those other factors mentioned.
> > We could Fogel lab the thing. Calling
>> each other names hasn't resulted in any insight.
--
RonSonic
No. I don't want to. You measure it.
someone
action (mainly in bends) within a Bowden wire not due to material
elasticity. This was highlighted in the difference in performance
with plastic covered and fibre/fabric covered housings. There is the
solution to housing compaction, use a stiffer supporting wrap.
Rolling a concave section on one edge of the rectangular wire that
forms the spiral housing could help prevent dislocation of the spiral
which results in both loss of action and friction against the inner.
A lot cheaper process than Nokon's. Then again, so is a stiff fibre
wrap a lot cheaper.
AMuzi
RonSonic wrote:
>Calling each other names hasn't resulted in any insight.
Radical thought. Perhaps an outlying data point for usenet.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
Bill Bushnell
> It's not possible. But you've got me thinking on this on
> different ways of connecting the bearing to the lightweight peripheral
> rim. Ezekiel's vision again comes to mind, I'm thinking of a way of
> reducing the mass of tensile elements nearest the bearing so reducing
> the overall mass of the lightest wheels, still using steel for its
> reliability and cost advantage.
Perhaps some sort of tensioned mesh connecting hub and rim.
> > Do you know of any online photos of wheels "built to your standard"? ?I can't
> > envision what you're advocating.
> I've said it before, you wont see the difference in a completed wheel
> with the naked eye over an overstrung wheel with a deep rim. Using
> soft spokes makes the forming much easier and cheaper.
Do you know of any online photos of spokes that were modified according to your
specs and then removed from the wheel? Do these spokes retain their modified
shape outside of the wheel, or do they appear like new, straight spokes?
> A good wheel needs to have an element of give. This must be
> controlled within the tyre and the rest of the wheel. The rim/spoke
> assembly should not be overly rigid (neither should the tyre, hence
> pnuematics) because wheel replacement is usually quicker and cheaper
> than frame repair (if possible).
> Distortion of material causes hysteresis losses in the metal wheel
> components and its tyre.
Are you claiming that hysteresis loss occurs to a signficant degree in the metal
parts of the wheel in the absence of yielding?
someone
> someone <thirty-...@live.co.uk> wrote:
> > It's not possible. But you've got me thinking on this on
> > different ways of connecting the bearing to the lightweight peripheral
> > rim. Ezekiel's vision again comes to mind, I'm thinking of a way of
> > reducing the mass of tensile elements nearest the bearing so reducing
> > the overall mass of the lightest wheels, still using steel for its
> > reliability and cost advantage.
>
> Perhaps some sort of tensioned mesh connecting hub and rim.
I doubt it could match 28 x 17swg spokes. I'd like the new wheel to
have all the advantages of a typical bicycle wheel. The new 'spoking'
will be repairable, but more involved.
> Do you know of any online photos of spokes that were modified according to your
> specs and then removed from the wheel? Do these spokes retain their modified
> shape outside of the wheel, or do they appear like new, straight spokes?
Don't know of any photo's. Yes the spokes retain their bent (kinked)
form. They are plastically deformed and hold their position whether
tight or loose.
>
> > A good wheel needs to have an element of give. This must be
> > controlled within the tyre and the rest of the wheel. The rim/spoke
> > assembly should not be overly rigid (neither should the tyre, hence
> > pnuematics) because wheel replacement is usually quicker and cheaper
> > than frame repair (if possible).
> > Distortion of material causes hysteresis losses in the metal wheel
> > components and its tyre.
>
> Are you claiming that hysteresis loss occurs to a " in the metal
> parts of the wheel in the absence of yielding?
No , I dont know "signficant degree" values. There are losses in the
metal and the pneumatic tyre due to hysteresis, the reasoning behind
rock hard tyres with thin treads. This is and was not the purpose of
my spoke modification, it is the greater wheel stability when riding.
The main gain in efficiency I believe is because of a more accurately
tracking wheel. Tensioning and truing such a wheel is greatly
speeded up, another part to its efficiency.
Michael Press
Jobst Brandt <jbr...@sonic.net> wrote:
> As I have often mentioned, spoke tension can be assessed by the tone
> emitted when plucked (near the spoke nipple), and that tone remains
> unchanged for the top spokes when a wheel is vertically loaded and
> unloaded. In contrast bottom spokes change their tone greatly under
> the same loading test.
I explained this to then ran this experiment for
a bike shop mechanic, and he _still_ did not acknowledge
the force of the argument.
--
Michael Press
Michael Press
RonSonic <rons...@tampabay.rr.com> wrote:
> No doubt some stretching occurs just as it does when you drive one car over a
> suspension bridge. Don't know that it makes a difference or that this stretching
> is permanent.
When a suspension bridge is loaded the elastic
deformation is negligible. What changes is the
geometry of suspension cable, hanger cables, and roadway.
--
Michael Press
Stephen Bauman
really?
http://www.youtube.com/watch?v=DgXveBf_l6k
look at the suspender cables, the vertical cables and the truss work.
Stephen Bauman
Tim McNamara
Michael Press <rub...@pacbell.net> wrote:
Given how common that is here in r.b.t., I am not surprised.
Tom Sherman °_°
>>
>
> An argument.
OH, oh I'm sorry, but this is abuse...you want room 12A, Just along the
corridor.
Tim McNamara
RonSonic <rons...@tampabay.rr.com> wrote:
> On Wed, 19 Aug 2009 21:07:26 -0700, jim beam <m...@privacy.net> wrote:
>
> >tell you what ron - /you/ hammer some engineering into jobst's thick
> >head and this nonsense can stop. start with his recent howler,
> >"brake cables do not stretch elastically in use".
>
> Two thoughts on that; first, you aren't hammering anything except the
> keyboard because Jobst's head remains completely unaffected.
LOL!
> Second I'm not sure they do to any meaningful extent. Rubber brake
> blocks, aluminum levers and caliper arms all flex so much more that
> this isn't something I can feel. I don't know that the housing
> doesn't collapse as much as the cable elongates and I'm pretty damn
> sure some portion of that will be the strands trying to straighten
> themselves. Except for cables that have undergone some severe drawing
> or rolling process there's going to be some constriction as they
> bundle themselves tighter as well. So we've got a few mechanisms for
> elongation that don't require elastic stretching and so much other
> stuff bending and compressing, I'm not sure. I've got a lot of
> experience with music wire, but it's not the same stuff despite the
> nickel steel content.
Since there are so many other elements that flex or compress much more
freely in the path of the force applied to a brake cable, it's quite
possible that there is little to no stretch. Were the rest of the
system perfectly rigid, then some cable stretch might be an issue.
> No doubt some stretching occurs just as it does when you drive one
> car over a suspension bridge. Don't know that it makes a difference
> or that this stretching is permanent.
Probably no (or virtually no) stretch and all flex on a suspension
bridge.
This provided a formula for determining stranded cable stretch based on
various factors. I can't verify any of the information, so I'll leave
that to others and just toss it out there.
http://www.s3i.co.uk/wiretehnical.php
http://www.bergencable.com/technology/technology_cable101.html
Examination of a brake cable in my parts box finds a 7 strand core
wrapped in one direction with an 11 strand outer wrapped in the opposite
direction. According to the first site, the initial permanent stretch
from the stands bedding in can be 0.1% for a 1x19 cable, which would be
1.6 mm over a 1600 mm cable. Once that stretch is taken up, then the
question of how much it stretches under dynamic loading comes into
consideration.
On the bike I just measured, the rear brake cable is 1250 mm long and
the front is 550 mm.
Elastic Stretch = (W x L) / (E x A)
W = Applied Load ( kN )
L = Cable length ( mm )
E = Strand Modulus ( kN/mm2)
A = Area of Cable = (D2 x pi) / 4 (where D= Dia of cable mm)
Typical values for E are:
1x19 = 107.5 kN / mm 2
7x7 = 57.3 kN / mm 2
7x19 = 47.5 kN / mm 2
Dyform = 133.7 kN / mm2
According to:
http://www.bikepro.com/products/brakes/brakecable/brkcbl_tabl.html
brake cables vary in diameter from 1.45 mm to 2.04 mm. Let's pick 2 mm
for the sake of convenience.
If we go with these number (and assuming a brake cable with zero tension
at rest, which is not quite correct because of the tension caused by the
brake return springs), then we have:
W = 0.2 kN (assuming 100N pull and a 2:1 ratio at the lever)
L = 1250 mm
E = 107.5 kN/mm^2
A = 1.57 (2 mm * 3.14159)/4)
(0.2 * 1250)/(107.5 * 1.57)
= 250 / 168.78
= 1.48 mm or 0.12% stretch.
This would indicate that at the outside, a bit less than 4 mm of lever
travel with a 100N (22.5 lb) force would be due to cable stretch. The
rest would be due to brake pad travel, brake pad compression, frame
flex, brake arm flex, brake housing flex and compression, cable
stop/hanger flex, and brake lever flex. The 100N force is probably an
excessive panic stop force, at least when using the rear brake since the
wheel would be skidding at that point. If we look at the front brake
with its 550 mm cable, the stretch is only 0.65 mm.
Basically, brake cable stretch is pretty negligible except in badly
adjusted brakes only allowing marginally acceptable lever travel.
> Now we can analyze the hell out of it. We could Fogel lab the thing.
> Calling each other names hasn't resulted in any insight.
Never does, it just puffs up the ego.
Tim McNamara
In article <timmcn-138BF1....@news.iphouse.com>,
jim beam
that's impossible - to change geometry, there has to be elastic deformation.
jim beam
> Oops, wrong thread! I'll repost.
>
you're a fucking retard timmy.