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Old 01-12-10, 01:39 PM   #1
Soil_Sampler
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Calibration

Non-FSA tensiometer calibration tool.
http://wheelworks.co.nz/blog/spoke-t...r-calibration/
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Old 01-12-10, 02:12 PM   #2
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That's pretty much what we used to calibrate them at Trek.
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Old 01-12-10, 02:42 PM   #3
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Facom tools... sweeeeeet !
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Old 01-12-10, 02:55 PM   #4
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How is it possible for someone who is supposedly super pro at building wheels using a $60 consumer level tensionmeter that doesn't even come close to the accuracy of a DT swiss tensionmeter? Really?
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Old 01-12-10, 03:30 PM   #5
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I use two Operator...the Wheelsmith and the Park.

Both aren't too bad...and I often compare the two.

The Wheelsmith has horrible resolution...but is quicker and easier to use.
The Park has better resolution...but quite frankly is very big, bulky...slower to work with.

Thing I always do with both is wiggle a tad after spoke attachment BEFORE I do a reading. Both tend to read very high until they settle down after a slight wiggle. The Park is the worst offender. It will sometimes drop a whole whopping 20 kgf after a slight wiggle...and in doing so read more consistently and pretty much match what the Wheelsmith is reading.

Thing I really hate about the Park tool - is that I am very very afraid to drop the thing. It really does look and feel that flimsy in its construction.

Overall...I prefer the Wheelsmith. In the future, will probably go DT or FSA...and then have 3 to play with!

So far, they do the job.

=8-)
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Old 01-12-10, 03:32 PM   #6
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Also, question for you Operator...will the DT or FSA fit inside a 36 hole 20" wheel?

=8-)
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Old 01-12-10, 05:13 PM   #7
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accuracy?

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Originally Posted by operator View Post
How is it possible for someone who is supposedly super pro at building wheels using a $60 consumer level tensionmeter that doesn't even come close to the accuracy of a DT swiss tensionmeter? Really?
Do you know what the +/- in accuracy is between the two?
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Old 01-13-10, 02:21 AM   #8
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How is it possible for someone who is supposedly super pro at building wheels using a $60 consumer level tensionmeter that doesn't even come close to the accuracy of a DT swiss tensionmeter? Really?
Hi guys - thats my calibration jig in the above photo.

The two important aspects with a tension meter are it's accuracy and it's repeatability. Accuracy is how true it reads and by calibrating it with that jig I can ensure that it's accurate. Repeatability is really important because you need the tension meter to read the same if you measure the same spoke 10 times in a row. In both respects the Park is very good

I find the Park tension meter to be very repeatable and once calibrated is very accurate and holds it's calibration very well. There are plenty of more expensive tension meters available but I find the Park accurate, repeatable and easy to use which is why I use it :-)

I've used a file to remove a small amount of material from the body of the tension meter so that with high spoke count wheels it doesn't hit the spoke next to what is being measured - this makes it a bit easier to use especially on 24" wheels.

-Tristan
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Old 01-13-10, 02:22 AM   #9
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Facom tools... sweeeeeet !
The screwdrivers are Snap-on :-)
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Old 01-13-10, 10:35 AM   #10
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Originally Posted by lab worker View Post
Hi guys - thats my calibration jig in the above photo.

The two important aspects with a tension meter are it's accuracy and it's repeatability. Accuracy is how true it reads and by calibrating it with that jig I can ensure that it's accurate. Repeatability is really important because you need the tension meter to read the same if you measure the same spoke 10 times in a row. In both respects the Park is very good

I find the Park tension meter to be very repeatable and once calibrated is very accurate and holds it's calibration very well. There are plenty of more expensive tension meters available but I find the Park accurate, repeatable and easy to use which is why I use it :-)

I've used a file to remove a small amount of material from the body of the tension meter so that with high spoke count wheels it doesn't hit the spoke next to what is being measured - this makes it a bit easier to use especially on 24" wheels.

-Tristan

I think you mean to use the terms "accuracy" and "precision".

=8-)


From a physics site:


ACCURACY
  • Accuracy descibes the nearness of a measurement to the standard or true value, i.e., a highly accurate measuring device will provide measurements very close to the standard, true or known values.Example: in target shooting a high score indicates the nearness to the bull's eye and is a measure of the shooter's accuracy. Refer to pictures below:
PECISION
  • Precision is the degree to which several measurements provide answers very close to each other. It is an indicator of the scatter in the data.The lesser the scatter, higher the precision. The pictures given below clearly describe Accracy and Precision.
=8-)
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Old 01-13-10, 01:57 PM   #11
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Higher learning...

Quote:
I think you mean to use the terms "accuracy" and "precision".
From a physics site:
I don't think he is a Physicist, or an Engineer. Chill with the terminology lesson.

lab worker

How much were the readings off on your Park tensiometer?
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Old 01-13-10, 05:57 PM   #12
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I don't think he is a Physicist, or an Engineer. Chill with the terminology lesson.

lab worker

How much were the readings off on your Park tensiometer?

Global cooling permafrost cramping your style?

=8-)
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Old 01-13-10, 07:13 PM   #13
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silly rabbit...

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Global cooling permafrost cramping your style?

=8-)
Seņor Conejo, 75 degrees during my ride today!

No cramps, no style and no teaching lesson...
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Old 01-13-10, 07:52 PM   #14
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Quote:
Originally Posted by lab worker View Post
Hi guys - thats my calibration jig in the above photo.

The two important aspects with a tension meter are it's accuracy and it's repeatability. Accuracy is how true it reads and by calibrating it with that jig I can ensure that it's accurate. Repeatability is really important because you need the tension meter to read the same if you measure the same spoke 10 times in a row. In both respects the Park is very good

I find the Park tension meter to be very repeatable and once calibrated is very accurate and holds it's calibration very well. There are plenty of more expensive tension meters available but I find the Park accurate, repeatable and easy to use which is why I use it :-)

I've used a file to remove a small amount of material from the body of the tension meter so that with high spoke count wheels it doesn't hit the spoke next to what is being measured - this makes it a bit easier to use especially on 24" wheels.

-Tristan
No, it's not.

Here's what i'm talking about. For a DT champion straight gauage 2.0 spoke (vast majority of bikes <$1k wheels), the difference between 24 and 25 is 107 to 121kgf. There is no in between. The TM-1 is not marked as such. That's the difference between a front wheel spoke tension and rear drive assuming 3x 32hole "standard" 700c wheel. The same range on a DT swiss can be subdivided into 10-12 more distinct kgf inside that range.

And as for repeatability screw that. I've taken multiple readings of the same spot on the same spoke which varies within that same range +/- 1 "unit" or worse depending on exactly how you release it. How are you supposed to build wheels with low spoke count/bladed spokes where the proper tension reads 0.3 on a DT swiss? You can't. Not with the park TM-1 anyways.
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Old 01-13-10, 10:13 PM   #15
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There is something to be said for 'deflection' curve over the "guess' given by the Park TM-1. Such as:



Magnify by download if needed.
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Old 01-13-10, 10:37 PM   #16
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Yep...it's pretty much a curve...and if you've had Trig, Calculus, Physics, Chemistry, yada yada, you pretty much know how to estimate an in between reading to be something approximating something much like when sampling soils.

Is a TM-1 reading between 24 and 25 a reading of 110? 115? 117? Quite frankly...I don't get too worked up over it. When I get a lot of 23's, 24's and 25's when reading all the spokes on a side - I'll just say that I'm in the 100 to 110 kgf ballpark and move on to the next wheel. I'll do the same for the Wheelsmith when I get a bunch of low 70's, 75's and near 80's.

Did that make sense?

I'll back off a tad though if the majority of my readings are 25s (TM-1) and solid 80's (Wheelsmith). I don't even go there even by accident with radial laced wheels.

Hey Soil Sampler...you said no lessons! Knock it off with the Spanish!

=8-)
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Old 01-13-10, 10:46 PM   #17
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Mananas Muchos Frier Rabbito...
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Old 01-13-10, 11:28 PM   #18
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Quote:
Originally Posted by mrrabbit View Post
Yep...it's pretty much a curve...and if you've had Trig, Calculus, Physics, Chemistry, yada yada, you pretty much know how to estimate an in between reading to be something approximating something much like when sampling soils.

Is a TM-1 reading between 24 and 25 a reading of 110? 115? 117? Quite frankly...I don't get too worked up over it. When I get a lot of 23's, 24's and 25's when reading all the spokes on a side - I'll just say that I'm in the 100 to 110 kgf ballpark and move on to the next wheel. I'll do the same for the Wheelsmith when I get a bunch of low 70's, 75's and near 80's.

Did that make sense?

I'll back off a tad though if the majority of my readings are 25s (TM-1) and solid 80's (Wheelsmith). I don't even go there even by accident with radial laced wheels.

Hey Soil Sampler...you said no lessons! Knock it off with the Spanish!

=8-)
You'll get worked up over it when reading a spoke yields +/- 1 and the difference between 1 unit is 20kgf. That means it could vary from 23-25. Which is unacceptable for a pro wheel.
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Old 01-13-10, 11:36 PM   #19
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The screwdrivers are Snap-on :-)
I believe he is referring to the hex wrenches. I have that exact same set
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Old 01-13-10, 11:39 PM   #20
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Gabacho

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Hey Soil Sampler...you said no lessons! Knock it off with the Spanish!
No habla ingles!
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Old 01-14-10, 01:17 AM   #21
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You'll get worked up over it when reading a spoke yields +/- 1 and the difference between 1 unit is 20kgf. That means it could vary from 23-25. Which is unacceptable for a pro wheel.
You still haven't answered a question I asked way back:

Will the DT or FSA tool work (fit) with a 20" 36H wheel? (I really would like my next tool to work with 20" upwards...instead of the current 24" upward....)

Answer me dangit!

=8-)
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Old 01-14-10, 02:12 AM   #22
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Originally Posted by mrrabbit View Post
You still haven't answered a question I asked way back:

Will the DT or FSA tool work (fit) with a 20" 36H wheel? (I really would like my next tool to work with 20" upwards...instead of the current 24" upward....)

Answer me dangit!

=8-)
YES & NO! Bite Me & Buy Insurance.
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Old 01-14-10, 02:40 AM   #23
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Quote:
Originally Posted by operator View Post
No, it's not.

Here's what i'm talking about. For a DT champion straight gauage 2.0 spoke (vast majority of bikes <$1k wheels), the difference between 24 and 25 is 107 to 121kgf. There is no in between. The TM-1 is not marked as such. That's the difference between a front wheel spoke tension and rear drive assuming 3x 32hole "standard" 700c wheel. The same range on a DT swiss can be subdivided into 10-12 more distinct kgf inside that range.

And as for repeatability screw that. I've taken multiple readings of the same spot on the same spoke which varies within that same range +/- 1 "unit" or worse depending on exactly how you release it. How are you supposed to build wheels with low spoke count/bladed spokes where the proper tension reads 0.3 on a DT swiss? You can't. Not with the park TM-1 anyways.
There is an in-between, it's just not a scribed line on the Park tool. I can easily use my eyes to divide within each whole number scribe marked on the tool into four sub-segments, giving me 24.0, 24.25, 24.5, 24.75 and 3.0. Reading 0.3 is no more difficult than reading at the scribed line. If you're eyes can't see the pointer is one quarter of the way between 24 and 25, they probably can't see the line itself, or for that matter, if you have any spoke threads exposed from the nipple.
Like most tools, the repeatability of the Park tool relies much on the skill of the user. Yes, it depends on how exactly you release it. Releasing it slowly and steadily, from the time it contacts the spoke, to the time your hand is no longer placing any pressure on the spring, gives me the same reading within this 0.25 increment. If you use it like a head mechanic I used to work with, by just letting it snap closed onto the spoke, I suspect you get about as much consistency as you would using an equally ham-fisted technique with any other tension meter.
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Old 01-14-10, 03:57 PM   #24
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I believe he is referring to the hex wrenches. I have that exact same set
Sorry - the hex wrenches and pliers in the photo are Facom; I just meant to add that the screwdrivers are Snap-on
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Old 01-14-10, 03:58 PM   #25
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I think you mean to use the terms "accuracy" and "precision".

=8-)
Thanks - precision is a better term judging by that description (although it's spelt wrong in the title)
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