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  1. #1
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  2. #2
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    Biggest issue would be insuring that it's calibrated. For my tensiometer I have a calibration setup so I have true readings for the spokes I use.

    It's basically a copy of the DT. Other things to look for would be quality of the pivots and spring. If there's play in the mechanism it can throw off readings too.

    It's a bit of a crap shoot.

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    Quote Originally Posted by ergott View Post
    Biggest issue would be insuring that it's calibrated. For my tensiometer I have a calibration setup so I have true readings for the spokes I use.

    It's basically a copy of the DT. Other things to look for would be quality of the pivots and spring. If there's play in the mechanism it can throw off readings too.

    It's a bit of a crap shoot.
    Please elaborate. How could I determine how accurate the calibration is? Since the item is sitting in China, I have no idea about its quality. For my one wheel a decade that I build, there is no utility in my buying a DT branded tensionometer. Since the decade is up, I will soon be building a wheel. This tool and its cheap price intrigues me.

  4. #4
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    Cheap tool from China... what could possibly go wrong?

  5. #5
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    The Park Tool tensionmeter is only $3 more...and is actually reputasble:

    Park Tool TM-1 Spoke Tension Meter | Jenson USA
    "Refreshingly Unconcerned With The Vulgar Exigencies Of Veracity "

  6. #6
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    You will not find "jet engine" precision at this price point, period. In general, tensiometers are good for checking relative tensions in order to get equal tensions throughout the wheel.

    The best thing to do is buy a tensiometer from your shop that is the same as the one they use. Then have them check the calibration relative to theirs. Note any discrepancies and factor that in when you build your wheels.
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

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  7. #7
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    Quote Originally Posted by daniell View Post
    Please elaborate. How could I determine how accurate the calibration is? Since the item is sitting in China, I have no idea about its quality. For my one wheel a decade that I build, there is no utility in my buying a DT branded tensionometer. Since the decade is up, I will soon be building a wheel. This tool and its cheap price intrigues me.
    I wouldn't trust that they took the time to calibrate it at that pricepoint, especially if they include a precision digital or analog gauge. In order for a tensiometer to work, the readings have to be checked against a known spoke at a specific tension. I have a jig set up that I can set a spoke at a known tension using a digital scale. Then I take readings with my tensiometer to see the results. If these measures aren't taken the tool isn't worth anything other than relative tension from spoke to spoke. You can just pluck the spokes and listen to them and achieve the same thing for free.


  8. #8
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    Quote Originally Posted by Lombard View Post
    The best thing to do is buy a tensiometer from your shop that is the same as the one they use. Then have them check the calibration relative to theirs. Note any discrepancies and factor that in when you build your wheels.
    That's assuming the shop keeps their tensiometer calibrated. I'd guess most don't.

  9. #9
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    Ergott. That is so funny we have almost 100% identical spoke tension calibration rigs/tools. I'm even using the same scale.

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    Quote Originally Posted by Lombard View Post
    The best thing to do is buy a tensiometer from your shop that is the same as the one they use. Then have them check the calibration relative to theirs. Note any discrepancies and factor that in when you build your wheels.
    I don't think using one that's been tossed around a shop for who knows how long by who knows who as the Gold Standard is a good idea. And you wouldn't have a way of knowing which one was right so not sure what noting discrepancies would do for you.

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    Quote Originally Posted by Jay Strongbow View Post
    I don't think using one that's been tossed around a shop for who knows how long by who knows who as the Gold Standard is a good idea. And you wouldn't have a way of knowing which one was right so not sure what noting discrepancies would do for you.
    It would give you a ballpark idea, nothing more. I would not trust sending it back to Park Tool to get it recalibrated as a gold standard either. As I stated before, nothing about any of these meters has "jet engine precision". It's a freaken spring for crying out loud!
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

    "Beware of geeks bearing formulas."
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    Quote Originally Posted by Lombard View Post
    It would give you a ballpark idea, nothing more. I would not trust sending it back to Park Tool to get it recalibrated as a gold standard either. As I stated before, nothing about any of these meters has "jet engine precision". It's a freaken spring for crying out loud!
    How would you know which ball park is the right one? And why would you pick the one with the unknown history over fresh from the factory as the ball pack to use.

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    Quote Originally Posted by Jay Strongbow View Post
    How would you know which ball park is the right one? And why would you pick the one with the unknown history over fresh from the factory as the ball pack to use.
    Well unless there is a large discrepancy, one could assume (I know that's a dangerous word) that they are both reasonably accurate for our purpose. When I compared mine to my shop's, mine read one graduation lower than theirs. You could also use a known wheel as a reference as well.

    My question now becomes - how would YOU go about proving accuracy of a non-precision device like this? Do you know or are you just being contradictory?
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

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  14. #14
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    Quote Originally Posted by daniell View Post
    Please elaborate. How could I determine how accurate the calibration is? Since the item is sitting in China, I have no idea about its quality. For my one wheel a decade that I build, there is no utility in my buying a DT branded tensionometer. Since the decade is up, I will soon be building a wheel. This tool and its cheap price intrigues me.
    Well, it's cheap, but looking at the pics, it seems you need to use a drop indicator with it. That would make it "not worth it" for me.
    "L'enfer, c'est les autres"

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    Quote Originally Posted by Lombard View Post

    My question now becomes - how would YOU go about proving accuracy of a non-precision device like this? Do you know or are you just being contradictory?
    As Ergott specified.

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    I've always thought about building a machine to check calibration something along the lines of what you have. Question. How do you know the digital scale is accurate/calibrated.
    Quote Originally Posted by ergott View Post
    I wouldn't trust that they took the time to calibrate it at that pricepoint, especially if they include a precision digital or analog gauge. In order for a tensiometer to work, the readings have to be checked against a known spoke at a specific tension. I have a jig set up that I can set a spoke at a known tension using a digital scale. Then I take readings with my tensiometer to see the results. If these measures aren't taken the tool isn't worth anything other than relative tension from spoke to spoke. You can just pluck the spokes and listen to them and achieve the same thing for free.


  17. #17
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    Scales like these are accurate to a kg or two. It's more than accurate enough for the purpose.

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    That appears to be a direct copy of the DT Swiss Tensiometer. Note it reads on mm, so you need a chart to convert to actual tension. But I see no mention of any chart provided.
    More on the subject and a picture of the DT Swiss unit here -
    https://www.wheelpro.co.uk/support/tensiometers/

    Agreed in general that unless your individual unit is supplied calibrated, you need to verify/check/calibrate it yourself. Measuring a couple of known good wheels that use generic / similar spokes to what you intend to build can also be a sanity check.

    These tools are good for indicating even tension on spokes, not getting the value to .01% precision. The readings are mostly quite repeatable, provided your technique is repeatable.

  19. #19
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    Quote Originally Posted by ergott View Post
    Scales like these are accurate to a kg or two. It's more than accurate enough for the purpose.
    I hung a certified 75lb weight on mine. It was pretty dang close.

    Last edited by Enoch562; 2 Weeks Ago at 01:38 PM.

  20. #20
    hfc
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    A very realistic option is to build the wheelset without using a tensiometer.

  21. #21
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    Quote Originally Posted by hfc View Post
    A very realistic option is to build the wheelset without using a tensiometer.
    That would work if you have a good ear and know what the pitch should be of properly tensioned spokes. I've tried this and it didn't work for me. Neither did a tuner attached to the stand.
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

    "Beware of geeks bearing formulas."
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  22. #22
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    There's more margin for error with higher spoke counts. You can follow Jobst's guidelines for tension in his book.

  23. #23
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    Quote Originally Posted by Lombard View Post
    That would work if you have a good ear and know what the pitch should be of properly tensioned spokes. I've tried this and it didn't work for me. Neither did a tuner attached to the stand.
    I think most of us can use pitch to find "exceptions". Pluck all spokes, and find/mark the ones that sound different than the rest. And assume most know the difference between lower / higher frequency when plucked. I usually find a lower one next to or between two higher pitch ones.

    Also as before, if you have a few pairs of known good wheels, you can do a direct compare of spoke pitch with an unknown wheel set for a sanity check.
    Most of these tools rely on the linearity of a steel spring to take the readings. In general, steel does not "go bad" or change properties over time when kept in the elastic region, with small displacements.
    With large displacements fatigue can happen, but even then, the
    number of cycles is enormous.

    Can anyone who uses these tool calibrators share experiences with a tools change in calibration (using the same reference spoke) over time?

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