Park tension gauge test



On 27 Dec 2006 02:45:40 GMT, [email protected] wrote:

>Carl Fogel writes:

[snip]

>> You could test for accuracy by hanging known weights in the normal
>> spoke tension range on a spoke and comparing readings from a ~$60
>> Park gauge and a ~$400 DT gauge. Possibly some bike magazine has
>> compared the accuracy of different spoke tension gauges, but I don't
>> know of any articles.

>
>That will get you nowhere. That does not affect stiction which in a
>sense is micro-welding. That is why I chose a rounded anvil to press
>on the spoke.


Dear Jobst,

The comparison test seems obvious and practical.

Take ten readings with each gauge on a spoke with a 100 kg weight
hanging from it.

The averages for the results from the look-up tables could be above,
below, or right on 110 kg tension.

One gauge could have a smaller variation in its ten results.

It doesn't matter how the gauge achieves a more accurate absolute
reading (as close to 100 kgf as possible) or how it reduces the
variation in readings.

I expect that roller-bearing posts would reduce variation, but I don't
know how much--that would take testing with a $400 tool.

For building bicycle wheels, I suspect that the ~$60 Park gauge is
accurate enough.

Cheers,

Carl Fogel
 
J

jim beam

Guest
[email protected] wrote:
> Carl Fogel writes:
>
>>>> Friction, for example, confuses things. When the hammer bends the
>>>> spoke, it tries to drag the spoke inward over both posts. This
>>>> raises the tension slightly, so the lower the hammer force, the
>>>> less frictional distortion. The Park posts are just fixed,
>>>> polished metal, but I think that more expensive gauges may have
>>>> roller-posts to reduce friction.

>
>>> How much do you suppose friction might affect readings? In the
>>> other thread where I posted a photo of my sanded (or similar process
>>> reduced diameter) butted spokes, there is clearly a texture on the
>>> spoke that would perhaps make friction a bigger issue with a solid
>>> post tool like the Park. I wonder if my spokes were much looser
>>> than I thought.

>
>> I don't know what the practical effect of the friction would be.
>> But I suspect that the friction for ordinary-finish spokes is pretty
>> much accounted for on the Park tables.

>
> Stiction is a problem with these instruments and that is why I used
> ball bearings to support the spoke. You can find how much effect that
> has with your instrument by rotating it a few degrees about the spoke,
> returning to the position from which you started. This releases
> stiction and also shows the zeroing effect that is not present by
> giving a different reading depending on where the instrument is
> stopped. A common way of reducing stiction is to vibrate the subject
> (spoke) by tapping on it, lightly yet sharply, without changing its
> position.


so how much difference does it make? if you want to get really
pedantic, you also need to allow for localized [elastic and plastic]
deformation at the contact points, [something exaggerated by the
"stiction relief" method you propose] but clearly, that's not going to
amount to much.

>
>> You could test for accuracy by hanging known weights in the normal
>> spoke tension range on a spoke and comparing readings from a ~$60
>> Park gauge and a ~$400 DT gauge. Possibly some bike magazine has
>> compared the accuracy of different spoke tension gauges, but I don't
>> know of any articles.

>
> That will get you nowhere.


eh? measuring /known/ tension won't get you anywhere?

> That does not affect stiction which in a
> sense is micro-welding. That is why I chose a rounded anvil to press
> on the spoke.


you're missing the point.

>
>> For practical wheel-building purposes, I suspect that the Park
>> tension gauge works fine. That is, it will give reasonably accurate
>> absolute tension (mine showed ~187 pounds for a known weight of ~190
>> pounds) and it will show small tension differences--I've tested a
>> number of spokes with squeeze forces in 21 steps from 0 to 100
>> pounds, and the gauge reflected the 5-lb squeeze force increase.

>
> I see bicycling is once more being so provincial that the term
> tensiometer must remain foreign as do many other concepts in bicycle
> hardware.
>
> http://www.m-w.com/dictionary/tensiometer


jeepers, that's disingenuous. jobst, even if you didn't know the first
thing about tensiometers, [and i wonder about you in this regard since
you don't know about wire stiffness as a function of thickness] hanging
known weights to produce known tension, then making a table of results
/will/ give you a usable tool, stiction and all. insulting claptrap
about definitions of the word can't disguise this fact, much as you want
to trivialize and dismiss it.

>
>> I doubt that it matters for practical wheel building whether your
>> absolute tension is 100, 110, or 120 kgf, any more than it matters
>> whether the tensions are all within 5 kgf or each other, or the rim
>> is true to within 0.1 mm, 0.5 mm, 1.0 mm, or even 2.0 mm.

>
> If you have access to better information, why not get it. Try
> wiggling your tensiometer and see what you get.


what do /you/ get?

>
>> In any case, your spokes are almost certainly looser than you think.
>> After all, on a narrow, well-braced 700c rim, Dianne's tests showed
>> that inflating the tire "to 120 psi dropped this spoke's tension
>> from about 99 kgf to about 83 kgf, a decrease of about 16 kgf or
>> roughly 35 pounds."

>
> That is only a problem for folks who use the instrument to tune the
> wheel, every spoke reading the same value. This reminds me of gears
> on bicycle, that some folks use to start at a traffic light running
> through six to eight gears like a loaded highway truck. Gears are for
> climbing hills, tensiometers are for assessing wheel tension, a couple
> of spokes after final tensioning will do.


so what?

>
> http://tinyurl.com/67gwc
>
>> So anyone who tensions spokes on a bare rim to 100 kgf is probably
>> actually riding around on spokes tensioned to only 83 to 90 kgf, a
>> considerably larger error than is likely with the Park tension
>> gauge.

>
> That number isn't so fixed as it may seem, rims being of different
> materials and cross section and having a different number of spokes.


spoke count doesn't determine tension jobst.

> An example of this effect is in "the Bicycle Wheel" just to avoid
> great discoveries being made about this later. My spokes have the
> tension that I measure. What is done with the wheel subsequently is
> another matter.


istr you having a great deal of difficulty saying what tension you
actually use. so as to avoid being seen to climb down on this whole
fiasco about "tension as high as the rim can bear" presumably.
 
T

Tosspot

Guest
Paul Hobson wrote:
> [email protected] wrote:
>
>>Elsewhere, doubts have been cast on the accuracy of Park's modestly
>>priced blue bicycle spoke tension gauge.
>>
>>Hmmm . . . I'd never tested my trusty (?) Park tension gauge!


<respect>

It was so simple, so effective, so right, but would have anyone else
tried it? Is there *any* part of a bicycle you've not submitted to a
test? I ask out of interest, because I bent my steering tube hitting a
tree and I've wondered how much force that took...
 
On Fri, 29 Dec 2006 19:24:00 +0100, Tosspot <[email protected]>
wrote:

>Paul Hobson wrote:
>> [email protected] wrote:
>>
>>>Elsewhere, doubts have been cast on the accuracy of Park's modestly
>>>priced blue bicycle spoke tension gauge.
>>>
>>>Hmmm . . . I'd never tested my trusty (?) Park tension gauge!

>
><respect>
>
>It was so simple, so effective, so right, but would have anyone else
>tried it? Is there *any* part of a bicycle you've not submitted to a
>test? I ask out of interest, because I bent my steering tube hitting a
>tree and I've wondered how much force that took...


Dear T.,

Definitive work has yet to be done on the proper installation of
playing cards in bicycle spokes.

Should the cards be stress-relieved? Some say yes, but others say that
it's just marking the deck and will get you in trouble in Las Vegas.

There is, however, universal agreement that only one brand of playing
cards is suitable for insertion into bicycle wheels.

Cheers,

Carl Fogel
 
S

Stephen Greenwood

Guest
[email protected] wrote:

> There is, however, universal agreement that only one brand of playing
> cards is suitable for insertion into bicycle wheels.


I don't know if it's *quite* universal. There may be a small enclave
who ride Torpedo hubs and disagree with you...

Thanks for performing the test.

Best,
Stephen Greenwood
 
On 29 Dec 2006 13:23:08 -0800, "Stephen Greenwood"
<[email protected]> wrote:

>
>[email protected] wrote:
>
>> There is, however, universal agreement that only one brand of playing
>> cards is suitable for insertion into bicycle wheels.

>
>I don't know if it's *quite* universal. There may be a small enclave
>who ride Torpedo hubs and disagree with you...
>
>Thanks for performing the test.
>
>Best,
>Stephen Greenwood


Dear Stephen,

Damn the torpedoes!

Such claims have been made, but they never hold water. They will blow
up and sink without a trace.

Only one brand of playing card is suitable for inserion into spoked
wheels. Had the USS Hartford been a sidewheeler instead of a
steam-screw, I would have ordered Bicycle playing cards inserted into
its spokes before steaming into battle.

Cheers,

D.G. Farragut, USN (ret.)
 
A

A Muzi

Guest
> [email protected] wrote:
>> There is, however, universal agreement that only one brand of playing
>> cards is suitable for insertion into bicycle wheels.


Stephen Greenwood wrote:
> I don't know if it's *quite* universal. There may be a small enclave
> who ride Torpedo hubs and disagree with you...


Huh? why not a standard Bicycle deck on a Torpedo?

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
 
On Fri, 29 Dec 2006 20:40:04 -0600, A Muzi <[email protected]>
wrote:

>> [email protected] wrote:
>>> There is, however, universal agreement that only one brand of playing
>>> cards is suitable for insertion into bicycle wheels.

>
>Stephen Greenwood wrote:
>> I don't know if it's *quite* universal. There may be a small enclave
>> who ride Torpedo hubs and disagree with you...

>
>Huh? why not a standard Bicycle deck on a Torpedo?


Dear Andrew,

http://www.kardwell.com/torpedo.htm

Cheers,

Carl Fogel
 
T

Tosspot

Guest
[email protected] wrote:
> On Fri, 29 Dec 2006 19:24:00 +0100, Tosspot <[email protected]>
> wrote:
>
>
>>Paul Hobson wrote:
>>
>>>[email protected] wrote:
>>>
>>>
>>>>Elsewhere, doubts have been cast on the accuracy of Park's modestly
>>>>priced blue bicycle spoke tension gauge.
>>>>
>>>>Hmmm . . . I'd never tested my trusty (?) Park tension gauge!

>>
>><respect>
>>
>>It was so simple, so effective, so right, but would have anyone else
>>tried it? Is there *any* part of a bicycle you've not submitted to a
>>test? I ask out of interest, because I bent my steering tube hitting a
>>tree and I've wondered how much force that took...

>
>
> Dear T.,
>
> Definitive work has yet to be done on the proper installation of
> playing cards in bicycle spokes.
>
> Should the cards be stress-relieved? Some say yes, but others say that
> it's just marking the deck and will get you in trouble in Las Vegas.
>
> There is, however, universal agreement that only one brand of playing
> cards is suitable for insertion into bicycle wheels.


<cough> Now you come to mention it, Dal Negro Torcellos would be rather
fine I think. Bit thicker and stiffer than Kems, fully plastic of
course, and a bit cheaper.
 
T

Tom Ace

Guest
[email protected] wrote:
> This reminds me of gears
> on bicycle, that some folks use to start at a traffic light running
> through six to eight gears like a loaded highway truck. Gears are for
> climbing hills, ...


If I recall correctly, your claim was that shifting gears
while accelerating from a stop is less efficient (takes
more time to get up to speed) than starting in a higher gear.
But time efficiency isn't the only concern. Some of us don't
want to start in high gears because our knees don't like that.

You've also pointed out how the pedal-crank attachment
is poorly designed and leads to fretting. You had the option
of machining conical surfaces on your equipment; those of
us who make do with stock parts can get longer life out of
them from not subjecting them to the higher forces associated
with using high gears. It's only when I push hard in high
gears that I hear creaking noises coming from the crank.

Tom Ace
 
Tom Ace writes:

>> This reminds me of gears on bicycle, that some folks use to start
>> at a traffic light running through six to eight gears like a loaded
>> highway truck. Gears are for climbing hills, ...


> If I recall correctly, your claim was that shifting gears while
> accelerating from a stop is less efficient (takes more time to get
> up to speed) than starting in a higher gear. But time efficiency
> isn't the only concern. Some of us don't want to start in high
> gears because our knees don't like that.


You don't need to make a racing start. Just don't push so hard. This
is not cruising up to a red light in a 52-11 gear... which is way to
high a gear for fragile knees anyway.

> You've also pointed out how the pedal-crank attachment is poorly
> designed and leads to fretting. You had the option of machining
> conical surfaces on your equipment; those of us who make do with
> stock parts can get longer life out of them from not subjecting them
> to the higher forces associated with using high gears. It's only
> when I push hard in high gears that I hear creaking noises coming
> from the crank.


I doubt you can hear creaking sounds from your cranks. That noise
originates elsewhere. However, the way you describe this, the bicycle
is riding you, not you riding the bicycle. Get a bicycle that can
take your strength and go for a ride.

Jobst Brandt
 

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