Calculating Spoke Length

Discussion in 'Wheel Building' started by Mikie, Jan 12, 2021.



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  1. Mikie

    Mikie Admin/iMTB Hooligan

    Location:
    North East Canada? , California
    Name:
    Mikie Watson
    Current Bike:
    Ibis DV9, Santa Cruz Hightower
    Obviously there are Online Spoke Calculators but having watched several Vids on, "How to calculate your spoke length" there are accurate ways to get your unique data and plug into Online Calculators to get a more accurate length for your spoke. These are the two I watched:



     
  2. mtnbikej

    mtnbikej J-Zilla

    Location:
    Orange
    Name:
    J
    Current Bike:
    SC Chameleon SS, SC Hightower
    I generally use 2 different spoke calculators when I run my spoke numbers.....just in case.

    My go to online calc is:
    http://www.kstoerz.com/freespoke/

    They have a nice library of hub and rim dimensions.
    I like that they give you the Spoke tension% for both sides
    Here is a sample I ran:
    https://kstoerz.com/freespoke/?link=1&rim=469&hub=318&n=32&xL=3&xR=3

    Screenshot (235).png

    There is also the the industry standard:

    https://spokes-calculator.dtswiss.com/en/calculator

    They have all the dimensions for DT branded parts, so if you wanna use it for some other hub manufacturer or rim, you'll have to provide those.

    The DT Spoke calc allows you to change the different nipple lengths which is kinda nice. It also rounds the spoke lengths to the recomended need.



    I have found that you can generally use a 1mm longer or shorter spoke length.....so if you need 16x 291 and 16x 292.....you could get 32x of just one size.
     
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  3. Mikie

    Mikie Admin/iMTB Hooligan

    Location:
    North East Canada? , California
    Name:
    Mikie Watson
    Current Bike:
    Ibis DV9, Santa Cruz Hightower
    Wow! That is really awesome J!

    As well, it's amazing how fragile a wheel "looks" compared to how strong they really are...
     
  4. Faust29

    Faust29 Moderator

    Location:
    irgendwo
    Name:
    B. Bunny
    Current Bike:
    2 SC and a STDM
    There's math involved ? I can barely remember my phone number nowadays. :thumbsdown:
     
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  5. Danmtchl

    Danmtchl iMTB Rockstah

    Location:
    Bakersfield
    Name:
    Dan
    Current Bike:
    2020 Trek Fuel EX 9.7
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  6. Grego

    Grego iMTB Addict

    Location:
    Fullerton
    Name:
    joe
    Current Bike:
    WFO9
    Finally a use for that trigonometry class...


    formula2.png


    R = Rim radius (half the ERD)
    H = Hub flange radius
    F = Hub flange offset
    X = Cross pattern
    h = Number of spokes in the wheel
    d = Diameter of the spoke hole in the hub
     
  7. mtnbikej

    mtnbikej J-Zilla

    Location:
    Orange
    Name:
    J
    Current Bike:
    SC Chameleon SS, SC Hightower

    3IaBXRa.gif

    [​IMG]
     
  8. Mikie

    Mikie Admin/iMTB Hooligan

    Location:
    North East Canada? , California
    Name:
    Mikie Watson
    Current Bike:
    Ibis DV9, Santa Cruz Hightower
    I could not put it better myself!
    :coffee::gotnothing:What the hail @Grego !?!?!?
     
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  9. Faust29

    Faust29 Moderator

    Location:
    irgendwo
    Name:
    B. Bunny
    Current Bike:
    2 SC and a STDM
    Now, that I can still do! :Roflmao
     
  10. Seriously_Tho

    Seriously_Tho Newbie with Hope!

    Name:
    Alex Hearn
    Here are a couple resources in PDF format (uploading JPG's for preview) -

    Spoke Finder - specs on most common spokes like size, weight, gauge etc
    CalcAdvisor - Most common spoke calculators based on popularity with pro builders

    0776.jpg

    0777.jpg
     

    Attached Files:

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  11. Mikie

    Mikie Admin/iMTB Hooligan

    Location:
    North East Canada? , California
    Name:
    Mikie Watson
    Current Bike:
    Ibis DV9, Santa Cruz Hightower
    This is good stuff Alex... Thanks! :thumbsup:
     
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  12. Seriously_Tho

    Seriously_Tho Newbie with Hope!

    Name:
    Alex Hearn
    You bet, tons of stuff like this.

    Here's an interesting challenge - Where is ERD measured to, point to point?

    erd-here-or-here.jpg
     
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  13. Seriously_Tho

    Seriously_Tho Newbie with Hope!

    Name:
    Alex Hearn
    And an interesting test of nipples in challenging environments to see what happens. Spoiler alert, aluminum in carbon works just fine when kept mostly dry -

    Nipple-test.jpg
     
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  14. BonsaiNut

    BonsaiNut iMTB Rockstah

    Location:
    Troutman, NC
    Name:
    Greg P
    Current Bike:
    Santa Cruz Hightower CC XX1
    I have not had a problem with nipples corroding. My problem has been with nipples shearing - the heads breaking off - even when the nipples are less than 6 months old. Happened to me three or four times before I switched from aluminum alloy to brass... and has not happened since.

    nip2.jpg

    nipple.jpg
     
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  15. Seriously_Tho

    Seriously_Tho Newbie with Hope!

    Name:
    Alex Hearn
    Got a graphic for that too ;)

    Best practices for alloy nipples includes pushing the spoke deep into the head, so the nipple head is pushing on the rim to some degree rather than pulling & relying on material shear strength - which ain't great for either 7k AL or brass frankly. And then comes a better solution -

    torn-nipple.jpg
     
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  16. Sidewalk

    Sidewalk iMTB Rockstah

    Location:
    The road is where I call home
    Name:
    Josh
    Current Bike:
    N+1
    Damn, the nerd in me is going to have to do the math now.
     
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  17. Ricekrispyota

    Ricekrispyota Member

    Name:
    Dana Weinberg
    They have a nice library of hub and rim dimensions.
    I like that they give you the Spoke tension% for both sides
    Here is a sample I ran:
    https://kstoerz.com/freespoke/?link=1&rim=469&hub=318&n=32&xL=3&xR=3





    I have a question about the image from Kstoerz. It shows "tension distribution at 97% and 100% respectivly. How do you measure this "distribution"? I have a spoke tensionometer. My build shows 100% and 66%. Can someone explain how I get to these two number accurately? I don't want to overtension the right side. I would assume I bring the left side to full tension and then go 66% of that on the right side? Thanks.


    Spoke Length (2).PNG
     
    SS Barby likes this.
  18. mtnbikej

    mtnbikej J-Zilla

    Location:
    Orange
    Name:
    J
    Current Bike:
    SC Chameleon SS, SC Hightower
    You go to 100% of max spoke tension on the drive side.

    You go to 66% of max spoke tension on the non-drive side.

    So let's say max tension is 100kPf on the driveside, you would go to 66kPf on the non-driveside.

    But most rims these days go to 120kPf.....so it's on you to that math.

    In theory, as long as you go max tension on the driveside, the non-driveside usually just ends up being what it is that you get it to that makes the dish correct and rim true.
     
    SS Barby and Ricekrispyota like this.
  19. Ricekrispyota

    Ricekrispyota Member

    Name:
    Dana Weinberg

    Solid. Thanks for the info.
     



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