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  1. #1
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    Spoke Length Question

    Hi there, I'm building a set of wheels and I'm trying to figure out which length of spokes I need. I've ran all of the proper dimensions through some calculators and got these lengths:

    Rear (NDS and NDS) - 286.6mm

    Front NDS - 285.8MM

    Front DS - 287.1

    I'm trying to use Sapim spokes which come in 2mm increments. Can I just use 286s all around? or will it be hard to get the proper front wheel dish with the same length of spokes? Or should I try to find or custom cut some 287mm spokes for the NDS front wheel?

  2. #2
    changingleaf
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    There are several variables, but the wheel dish is not one. You control the dish and the spoke lengths are calculated around this dish. 286 is close and could work. It depends how accurate the ERD measurement is, how much you make the maximum spoke tension, and the gauge of spoke. Thinner spokes stretch more. For perfect spoke length and standard nipples you only have 1mm to play with and if the spokes are a little short you may end up putting too much stress on the nipple. Brass nipples can handle spokes that are a little short, they do not fatigue as fast as aluminum when they are put under tension. I recommend using brass nipples and giving it a try.

    Also, those lengths look a little strange. It's extremely rare to calculate the same length for the both sides of the rear wheel since it has significant dish because of the cassette. The front should only have dish if you have disc brakes and usually this would result in the NDS front spokes (disc side) being shorter. You may have labelled these wrong.

  3. #3
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    Quote Originally Posted by Warpdatframe View Post
    Hi there, I'm building a set of wheels and I'm trying to figure out which length of spokes I need. I've ran all of the proper dimensions through some calculators and got these lengths:

    Rear (NDS and NDS) - 286.6mm

    Front NDS - 285.8MM

    Front DS - 287.1

    I'm trying to use Sapim spokes which come in 2mm increments. Can I just use 286s all around? or will it be hard to get the proper front wheel dish with the same length of spokes? Or should I try to find or custom cut some 287mm spokes for the NDS front wheel?
    Methinks you've got front and rear switched in your post. Front doesn't have a DS and NDS.

  4. #4
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    I'm building a single speed mountain bike wheel set which is why the lengths seem odd. The rear is a 0 dish track style hub and the front is a disc hub with boost spacing.

    I'm also going to use Sapim Lasers which are a super thin spoke. The plan was to use aluminum nipples but it seems like most people are saying to use brass instead.

  5. #5
    A wheelist
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    Quote Originally Posted by Warpdatframe View Post
    The plan was to use aluminum nipples but it seems like most people are saying to use brass instead.
    Let's hope that "most people" are giving their opinions based on personal experience. Here's mine - in maybe 25-30 years of using aluminum nipples on my road, track and MTB wheels (Ok I have one set of road wheels that has brass nipples out of about 5 sets of current wheels) I have had one nipple failure and I think that was due to a spoke being a bit too short. But I'll admit that there is little (or nothing) to gain from aluminum nipples other than their plethora of colors. My current wheelset has green nipples.
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  6. #6
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    Quote Originally Posted by Mike T. View Post
    Let's hope that "most people" are giving their opinions based on personal experience. Here's mine - in maybe 25-30 years of using aluminum nipples on my road, track and MTB wheels (Ok I have one set of road wheels that has brass nipples out of about 5 sets of current wheels) I have had one nipple failure and I think that was due to a spoke being a bit too short. But I'll admit that there is little (or nothing) to gain from aluminum nipples other than their plethora of colors. My current wheelset has green nipples.
    Do you think I should be fine with 286s for both sides of the front wheel? Or should I try to find some 287mm spokes?

  7. #7
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    Quote Originally Posted by Warpdatframe View Post
    Do you think I should be fine with 286s for both sides of the front wheel? Or should I try to find some 287mm spokes?
    I don't think you mentioned this point but IMO it's the first thing that should be addressed before any opinion on spoke lengths is given - did you measure all the parts (rim ERD and hub dimensions) yourself? But assuming you did, then the old potato of "spoke lengths should be within +/-1mm of calculated lengths" has never failed me. You said you want to use Laser spokes and they do have some stretch. Roger Musson's Wheelpro calculator takes this into account. He's not blowing smoke as he wrote (and constantly modifies as needed) the calculator as his credentials are that he is an engineer.

    Measure rims and hubs as per his instructions and there is lots of ERD measurement stuff on my site.

    https://www.wheelpro.co.uk/spokecalc/
    Last edited by Mike T.; 3 Weeks Ago at 01:10 PM.
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  8. #8
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    Quote Originally Posted by Mike T. View Post
    I don't think you mentioned this point but IMO it's the first thing that should be addressed before any opinion on spoke lengths is given - did you measure all the parts (rim ERD and hub dimensions) yourself? But assuming you did, then the old potato of "spoke lengths should be within +/-1mm of calculated lengths" has never failed me. You said you want to use Laser spokes and they do have some stretch. Roger Musson's Wheelpro calculator takes this into account. He's not blowing smoke as he wrote (and constantly modifies as needed) the calculator as his credentials are that he is an engineer.

    Measure rims and hubs as per his instructions and there is lots of ERD measurement stuff on my site.

    https://www.wheelpro.co.uk/spokecalc/
    Thanks for the advice. I've done a bunch of reading on both of your site and Roger Musson's and both are very helpful. I was hoping to order the spokes and rims together but getting the rims first to measure would probably be the wiser move.

  9. #9
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    Quote Originally Posted by Warpdatframe View Post
    Thanks for the advice. I've done a bunch of reading on both of your site and Roger Musson's and both are very helpful. I was hoping to order the spokes and rims together but getting the rims first to measure would probably be the wiser move.
    I always do it in two shipments. Yeah sure that costs time and money but doing it the other way could add "frustration, stress and anger" to the first two. Not to mention that you're usually 95% into the wheel build when you find the spokes are the wrong length. Now you have a fist-full of used spokes.
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  10. #10
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    Quote Originally Posted by Warpdatframe View Post

    Can I just use 286s all around?
    if you're confident in your calculations, yes, most probably.
    Yossarian: don't worry. nothing's going to happen to you that won't happen to the rest of us.

  11. #11
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    Listen to Mike and follow Roger Musson's book to the letter.

    Order rims and hubs first. ALWAYS, ALWAYS, ALWAYS do you own measurements. NEVER, EVER trust manufacturers' stated ERD. I have already found manufacturers' stated ERD wrong TWICE!

    Use Roger's spoke calculator. He tells you in his book what is acceptable for rounding spoke sizes. Anything within 1mm should work.

    So, if your measurements are:

    Rear (NDS and NDS) - 286.6mm - use 286mm

    Front NDS - 285.8mm - use 286mm

    Front DS - 287.1 - use 288mm

    I really think compensating for extra stretching of thinner spokes is over analyzing the situation. You're not going to bottom out on a 1mm difference. And Roger's spoke calculator takes this into account anyway.

    I will agree that brass nipples are the way to go. The weight difference is trivial and the peace of mind of not having threads corrode and break is priceless.

    Measure twice, build once.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  12. #12
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    Quote Originally Posted by Lombard View Post
    Use Roger's spoke calculator. He tells you in his book what is acceptable for rounding spoke sizes. Anything within 1mm should work.
    The book refers to the old calculator, with the new Wheelpro calculator, always round the fractional lengths up (see the calc help guide). Treat the calculated length as the minimum length.

    Work on the calculator continues. I'm putting in the option to calculate a full table of permutations like the old calc did (people keep asking me for this). Bit of coding still to do.

  13. #13
    wheelbuilder
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    I'd say that if your are confident with your measurements (key), I'd rely on the wheelpro calc recommendations.

    Sent from my SM-G950U using Tapatalk

  14. #14
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    Quote Originally Posted by roger-m View Post
    The book refers to the old calculator, with the new Wheelpro calculator, always round the fractional lengths up (see the calc help guide). Treat the calculated length as the minimum length.

    Work on the calculator continues. I'm putting in the option to calculate a full table of permutations like the old calc did (people keep asking me for this). Bit of coding still to do.
    Interesting. I just used your calculator back in mid-May. Has it changed since then?

    Round fractional lengths up? So are you saying for a 286.6mm measurement to use a 288mm spoke?


    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  15. #15
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    Quote Originally Posted by Lombard View Post
    Interesting. I just used your calculator back in mid-May. Has it changed since then?

    Round fractional lengths up? So are you saying for a 286.6mm measurement to use a 288mm spoke?
    The new calculator went live in January, so you've been using the new one. It takes into account elongation, and the method of rounding has changed (all explained on the About page, and Help page). Treat the calculated length as the bottom line, and don't cross it. It's logical, and makes spoke selection easier. So 286.6 rounds to 287 or 288.

    Old calculator
    https://www.wheelpro.co.uk/spokecalc-old/

    New calculator
    https://www.wheelpro.co.uk/spokecalc/

    The new calc is getting an option to display lengths like the old one did, as a table of permutations.

  16. #16
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    Quote Originally Posted by roger-m View Post
    The new calculator went live in January, so you've been using the new one. It takes into account elongation, and the method of rounding has changed (all explained on the About page, and Help page). Treat the calculated length as the bottom line, and don't cross it. It's logical, and makes spoke selection easier. So 286.6 rounds to 287 or 288.

    Old calculator
    https://www.wheelpro.co.uk/spokecalc-old/

    New calculator
    https://www.wheelpro.co.uk/spokecalc/

    The new calc is getting an option to display lengths like the old one did, as a table of permutations.
    Interesting. I guess I did use the new calculator, but didn't see anything different about rounding since there weren't any measurements that made it stand out.

    Thanks Roger!
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



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