Mavic Open Sport spoke tension?

Discussion in 'Cycling Equipment' started by biker jk, Jul 20, 2008.

  1. biker jk

    biker jk New Member

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    If anyone could help with information on the correct spoke tension for a Mavic Open Sport rim (32 x 3-cross DT champion 2mm round spokes) it would be most appreciated. I phoned a Mavic Service centre and was told they use 110-130kgf on all their Mavic wheels but that doesn't sound correct, especially since the Mavic (dealer) web site says 70-90kgf for 3-cross spoke lacing. Thanks.
     
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  2. daveornee

    daveornee New Member

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    100 kgf front & right rear. left rear is tensioned to center the rim.
     
  3. biker jk

    biker jk New Member

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    Thanks Dave. Why does Mavic say the following on its (dealer) web site for the Open Sport rim?

    "Respect the appropriate spoke tensions; Mavic recommends spoke tensions between 70 and 90 kg (for a front or rear wheel on the free wheel side with a crossed 3 pattern). Inappropriate spoke tension can generate too much stress and damage the rim;"
     
  4. daveornee

    daveornee New Member

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    Well, I can't answer for Mavic, but it seems they have a significant range of answers for themselves: 70 - 130 kgf depending on who you ask or what you believe from reading the site. 100 kgf is what I have been using for over 2,000 wheels. But.........................................................................
    I quit using Mavic a few years ago when cracking around the eyelets became a regular problem. I use the company from your homeland: Velocity.
    Questions you need to ask yourself:
    1. How accurately calibrated is your tension guage? (Hint: if it is off by 10% and you measure 90 kfg, will it be 81 or 99 kgf?)
    2. How much tension variation will you allow in your build? (Hint some builders specify +-10 and some +- 5%)
    3. When will you measure the "final" tension? (Hint: before or after bedding in the spokes).
     
  5. Peter@vecchios

    [email protected] New Member

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    Open Sport rims, a derivative of the poor MA-3, was prone to cracking around the single eyelet. Opensport is much improved and I have built many, at the 100 kgf level, w/o problem BUT that is a maxiumum, not to be exceeded. Many single eyelet rims, like Velocity Razor and DT 1.1 single eyelet have strict limits, 100kgf, and exceeding this encourages eyelets pulling out.

    I, too, like Velocity and DT, altho DT rim lineup is somewhat limited. mavic make fine rims but you must be careful in the build. Having said this, they are third on my list of preferred rims. DT, Velocity, Mavic.
     
  6. biker jk

    biker jk New Member

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    Thanks Dave and Peter for your very helpful response. I definitely won't be exceeding 100kgf on the Open Sports. I was after a budget wheelset (cost me A$150 for the two wheels) as it will be for a second bike.
     
  7. dhk2

    dhk2 Active Member

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    Interesting discussion. I'm not a wheelbuilder, but did have a Mavic wheel some years ago which failed around an eyelet. Spoke tension seemed high, judging by "pulling" distortion of the rim around the eyelets.

    My question is: what is the advantage of pushing spoke tension to the max ratings? Will the wheel stay true longer, or last longer before failure of spokes, rim or hub? Or, would a wheel built at 80 kgf tension be more durable?
     
  8. daveornee

    daveornee New Member

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    Conventional wheels derive strength from spokes in tension. Spokes stretch under tension based on their cross-section and tension. If/when they go slack, they no longer supply support to the rim. If you are lighter/have stiffer rim/have more spokes/never exceed 1G; you can use less and less tension.
    Another negative effect of loosing all tension in spokes is that nipples will loosen. When dynamic forces on the wheel make spokes go slack the nipples further unwind: thus the wheel continues in a "negative spiral".
    "Maximum" ratings are not where the rim will self destruct, but the top of the range the manufacturer considers useful during the life of the product. Go past the max: expect the tendancy to crack rims around the spoke holes; go low on the tension: expect the nipples to unwind and/or the rim to bend from lack of spoke support.
     
  9. dhk2

    dhk2 Active Member

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    Thanks for the response. I'm reading your answer partially as "it depends", but generally being near the top of the specified tension range is best for all-around durability.
     
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