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  1. #1
    mtbr member
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    Another...Spoke length question.

    I'm building up a set of Stan's Arch ex 29" rims with Chris King SD front and 142mm rear hubs. I plan on using DT comp spokes and brass nipples in a 3 cross pattern..Just have to ask one question. I know that Stan's isn't always spot on with ERD, so I measured it myself and came up with 606, which actually matches the updated labeling on the rim itself. I used the prowheelbuilder.com spoke calculator and they have 605 as their measurements. I put both ERD into the calculator both front and rear (also double checked my hubs measurements w/the sites and they are spot on) and I'm just wondering if I can get away with using one spoke length for the whole set. I was thinking of going up a size to 295 all-around...would that ~1mm be cutting it close to too short/too long? It would be awesome to have one box cover all my needs.


    Front

    w/606erd: Left spoke length: 294.1
    Right spoke length: 294.9


    Rear
    w/606erd Left spoke length: 295.2
    Right spoke length: 294


    Here are the numbers from prowheelbuilder with the 605erd:

    Left spoke length:*293.6 Right spoke length:*294.4
    Left spoke length:*294.7Right spoke length:*293.5

    Which would make things a little more complex rounding up and down to get one spoke size of 294.

    Let me know your thoughts, thanks!

    -Gabe
    Last edited by Gabriel J; 07-10-2013 at 06:27 AM.

  2. #2
    mtbpete
    Reputation: changingleaf's Avatar
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    I have built wheels with Arch EX 29 rims AND Chris King hubs. I use spocalc spoke calculator and use 606 ERD. The listed and measured ERD are not always the same or perfect since thin spokes such as revolutions will stretch more than competitions, rims may compress slightly, and the max tensions of the rim may vary. The Arch EX is constructed for 125kgf tension vs. the Crest at 100kgf, which is easily an extra revolution of the nipple.

    From Spocalc I get:
    Front Left and Right 292.8 293.6
    Rear Left and Right 293.9 292.7

    I used 293 left front and 294 right front, 294 left rear and 293 right rear.

    294 will probably work all around or 293 since you're using brass nipples which have a higher tensile strength than the aluminum nipples. BUT, ideally use the correct lengths listed above.

  3. #3
    transmitter~receiver
    Reputation: meltingfeather's Avatar
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    Do not use the prowheelbuilder calculator. It is garbage.
    King hubs are generally OK to use one length with, but use a decent calculator to check, Spokecalc or the DT Swiss calculator.
    Make sure you measure ERD according to the instructions here (click "Rims" then "Measuring Rims."
    Note that "nipple seat diameter" is not ERD, a simple mathematical fact.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  4. #4
    transmitter~receiver
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    Quote Originally Posted by changingleaf View Post
    The listed and measured ERD are not always the same or perfect since thin spokes such as revolutions will stretch more than competitions, rims may compress slightly, and the max tensions of the rim may vary.
    None of these things affect ERD.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  5. #5
    mtbr member
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    Thanks for the replies, I actually have Roger's book..it just happened to be saved on my laptop that died on me..I was using that as motivation to fix it, but I just downloaded a copy onto my tablet. I used the dt swiss calculator last night as well, was going to use spokecalc also but it was giving me fits on this damn tablet.

    I don't mind going with two lengths, it just seemed close enough that one length would be acceptable. Does anyone recommend a particular site to buy the individual spokes from if I go that route?

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