spoke calculation needed..

Discussion in 'Observed Trials Discussion' started by uownme, Feb 24, 2004.

  1. uownme

    uownme get high and eat her

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    Going to try out the rx32 up front and I need some new lengths for the wheel.

    rear dx32 32h 3x laced to a front dt swiss onyx disc hub

    Who wants to do that for me? Im to dumb to do the calcs. my self.. :bigthumb:
     
  2. bigd

    bigd Guest

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    i'll be at the shop tomorrow at noon
     

  3. oicdn

    oicdn Guest

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    Well considering you'll know the ERD of a DX32 is 550 and EVERY spoke calc has a Onyx hub...grab any spoke calc and figure it out......
     
  4. bigd

    bigd Guest

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    Onyx Disc FF w/ DX32 32h 3x

    L= 263.7 (264)
    R= 266.4 (266)
     
  5. uownme

    uownme get high and eat her

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    Your the man...
     
  6. trialsbug

    trialsbug New Member

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    OK Bigd . I have a tougher one to figure out this time. I have an Echo front mod rim (36h) and a Hope XC 36h front disc hub.

    I don't have any info on the Echo front rim. It is the drilled rim that comes on the Team. I was told that it is based on the Ryno Lite, but this rim is a single wall rim. Does anyone have the ERD for this rim? Would it be possible to figure out the ERD based on the current hub and spoke length or should I measure the ERD with two cut off spokes?
     
  7. bigd

    bigd Guest

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    the ERD of a rim is the diameter between the outer edges of the inner wall. so if you measure the inside diameter of a given rim, add the thickness of the inner wall twice (once per side). that will give you the distance between the surfaces the nipples pull against.

    if its based on the 20" rhynolite, then this is what you'll need...

    Hope XC Disc FF w/ 20" rhynolite 36h 3X=

    L= 184.7mm (185)
    R= 188.5mm (188)

    for spokes that short i'm not sure what lengths are easiest to come by, so if you have a shop order or cut some just round to the nearest number. (185L 188R) this is measured with the rhynolite ERD, so if you can confirm they're the same, then you're golden. the ERD measurement I have for the rhynolite is 395mm.
     
  8. trialsbug

    trialsbug New Member

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    This rim does not have an inner wall. I will try to get a rough estimate of the ERD to see of it looks like it is close to 395.

    Isn't the ERD actually measured to where the end of the spoke should be after building the wheel? This would make it the inside diameter + two times the wall thickness + 2 times the spoke head thickness. Is this correct? :?

    Thanks for the numbers bigd, I will let you know what I measure.
     
  9. bigd

    bigd Guest

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    yeah you're right, i got it mixed up. the erd should take into consideration the nipple head thickness. the end of the spoke usually will sit nearly at the end of the nipple head. so add the thickness of the innermost rim wall the nips pull against then add the thickness of the nipple heads you're using. if you go a bit shorter on the erd meausrement it can help to prevent the nipple bottoming on the spoke.
     
  10. trialsbug

    trialsbug New Member

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    I just measured the ERD. What I did was unlace the wheel and then measure the current spokes. They were 180mm. Then I put two spokes back in the rim on opposite sides so that the ends of the spokes were flush with the bottom of the screw driver slot in the nipple and measured between the spoked with my cheap plastic calipers. I measured 35mm. 180+180+35 =395, so your numbers should be correct.

    Since all of the wonderful Paint pics have really inspired me to create my own images, here is an image to show how I measured the ERD:

    [​IMG]

    Thanks, TrialsBug
     
  11. trialsbug

    trialsbug New Member

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    bigd, I sent you a pm with one last hub/rim combo that I need to figure out before I start ordering spokes for the wheels that I will be building. Thanks for all the spoke lengths that you have supplied so far.

    Now that I am going to be ordering spokes, does anyone know where I can get DT Competition spokes cheap. The lowest prices that I have seen have been at AEBike and Cambria so far. AEBike has a huge selection, but I would have to order 100 of each spoke length. Any other suggestions? I don't have a LBS, so that is not an option.