Tensiometer settings for CX-Ray spokes

Nick Payne
Nick Payne Posts: 288
edited May 2018 in Workshop
I'm about to build some wheels using Sapim CX-Ray spokes, and my Wheelsmith tensiometer, that I've had for about 20 years, doesn't have a calibration column for the 0.9x2.2 dimensions of the CX-Ray. The closest matches on the calibration chart are a column for 0.9x3.1 spokes or a column for 1.2x2.2 spokes (a given scale reading on the tensiometer correlates to about 10% higher tension on 0.9x3.1 than for 1.2x2.2). Anyone have any suggestion for a correction factor to apply for 0.9x2.2 spokes?

Comments

  • ugo.santalucia
    ugo.santalucia Posts: 28,311
    Very difficult with thin bladed spokes. You should really get it calibrated either with a proper device or you can calibrate it against a tensiometer which has a scale for CX-Ray.

    Where do you live?
    left the forum March 2023
  • Nick Payne
    Nick Payne Posts: 288
    With a bit of Googling, I've just noticed that Wheel Fanatyk in the US offer a re-calibration service for Wheelsmith tensiometers for $35 (http://www.wheelfanatyk.com/store/ws-tensiometer-recalibration/). I emailed them to ask if the service includes adding readout columns for modern spokes such as Sapim cx-ray/DT Swiss aerolite and Sapim d-light. Will see what they respond with.

    I suppose I could also make up a jig of some sort to take to the gym and hang successive 20kg discs off a spoke and measure the scale reading for each increase in weight.

    I live in Australia.
  • Nick Payne
    Nick Payne Posts: 288
    Well the response from Wheel Fanatyk is that they just re-calibrate for the same spoke sizes as the tensiometer originally came with, which are these:

    new-chart.jpg

    So I think I'll pursue my second option to calibrate it myself, using a setup like this, which is someone else's jig for calibrating their TM-1:

    IMG_2672%2B%25282%2529.JPG
  • ugo.santalucia
    ugo.santalucia Posts: 28,311
    I've seen smaller setups using a luggage scale
    left the forum March 2023
  • cycleclinic
    cycleclinic Posts: 6,865
    I should offer a calibration service with my jig.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • agent_buchwald
    agent_buchwald Posts: 256
    thecycleclinic wrote:
    I should offer a calibration service with my jig.
    I would pay for that.
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  • cycleclinic
    cycleclinic Posts: 6,865
    I am not sure what price would be fair for say readings from 300N to 1400N per spoke. It would take about 20 minutes in total including writing it all up. + postage.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • ugo.santalucia
    ugo.santalucia Posts: 28,311
    thecycleclinic wrote:
    I am not sure what price would be fair for say readings from 300N to 1400N per spoke. It would take about 20 minutes in total including writing it all up. + postage.

    I think it will take longer if you want to do a wide range of spokes. 30 pounds + postage sounds reasonable.
    left the forum March 2023

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