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Re-spoking wheels at a bike shop?

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    #16
    Originally posted by Oddity View Post
    Could you use that homegrown tool to accurately and repeatedly measure deflections between 2 spokes, at less than ~2mm, while applying between ~50-175kg of force? If so I'd love to know how to make it so I could rig one up myself. My Park tool is wearing out. They don't last forever, unfortunately, unless you buy a $250+ one for pro shops!
    I doubt it Odd.Although, if you had a basic dial indicator accuracy could be assured. Modify your Park?
    I am not a wheel builder and my experience with wheels is from my younger years of keeping my bike in relatively good shape with a spoke spanner and a shifter/screwdriver etc to hear the pitch - it worked well enough for me back then.
    I found this article interesting reading https://www.wheelpro.co.uk/support/tensiometers/

    Gotta sign off now, bowel care person has arrived

    P.S " My Park tool is wearing out."
    I never handled a Park tool but it appears that fulcrum and contact pins might wear - and could be replaced. Same with the spring.

    A dial gauge could be fitted to your Park tool - from what I can observe, that is the only(?) difference between it and the higher end stuff.

    I see that the Park tool can be got for US$51, here
    https://ideamobility.com/rear-wheels...ion-gauge.html
    ATB
    Last edited by slow_runner; 10 Feb 2021, 10:07 PM.

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      #17
      Cool, thanks for the info. I got the Park tool ages ago and rarely use it anymore. The one I have is for higher tension motor bike stuff from back when I was riding spoked wheel enduro/dirt bikes 15-20,000 miles a year! But it works on bicycle/wheelchair wheels too. It is the spring and posts wearing. I could replace the spring for cheap but once it's off the tool has to be recalibrated to ensure the specific settings relate back to the specific kg of force, which requires sending back to Park. They'll actually refurbish it for me, as a paid service, if I want. About half a new one, in total.

      But, I think, for low stress wheelchair wheel applications, where high speed and high impact forces aren't present during use, like they are on a dirt bike, using the old "tune the spokes to pitch" is probably fine.

      I would expect a bicycle pro-shop to use a displacement/tension measuring device though, regardless.
      "I have great faith in fools; self-confidence my friends call it." - Edgar Allen Poe

      "If you only know your side of an issue, you know nothing." -John Stuart Mill, On Liberty

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        #18
        Originally posted by Oddity View Post
        Cool, thanks for the info. I got the Park tool ages ago and rarely use it anymore. The one I have is for higher tension motor bike stuff from back when I was riding spoked wheel enduro/dirt bikes 15-20,000 miles a year! But it works on bicycle/wheelchair wheels too. It is the spring and posts wearing. I could replace the spring for cheap but once it's off the tool has to be recalibrated to ensure the specific settings relate back to the specific kg of force, which requires sending back to Park. They'll actually refurbish it for me, as a paid service, if I want. About half a new one, in total.
        But, I think, for low stress wheelchair wheel applications, where high speed and high impact forces aren't present during use, like they are on a dirt bike, using the old "tune the spokes to pitch" is probably fine.
        I would expect a bicycle pro-shop to use a displacement/tension measuring device though, regardless.
        Re, calibrating Odd. The extent that a Park tool could be 'calibrated' could only be achieved by changing out the spring and replacement of the pins. I would think that a new spring would be the primary option of such 'calibration'.
        The reason being that the back plate/pointer moves about a fixed point while the scale is integral to the top plate; therefore no 'calibration' can be achieved.
        The spoke/s of the wheel are of a known material and gauge so it follows that the amount of deflection between two points at a given force is all that is required. The spoke manufacturer should have that information available.
        Your observation on the stresses experienced by everyday chair wheels is valid although at the extreme end of use, as in sport pursuit, that build quality expectation would be far higher.
        In the end, an experienced wheel builder would rely on that 'feel' learnt over time. Maybe a mechanical tension meter is used at the end point/s or maybe finger feel, spoke note is sufficient?
        Did you read the link to the article by Roger Musson? I found it and the site to be informative and even; no BS or hype.
        Be well.

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          #19
          Originally posted by slow_runner View Post
          The reason being that the back plate/pointer moves about a fixed point while the scale is integral to the top plate; therefore no 'calibration' can be achieved..
          After finding an image of the moving rear plate, I take that comment back. It is simple, crude but fulfills its function. A DTI gauge would provide a better constant.


          Click image for larger version

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            #20
            I just replace my spokes myself when I replace my tubes. Just replace the broken ones don’t need to change them all.

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