Calculating Spoke Length

Mikie

Mikie

Admin/iMTB Hooligan
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:


 
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.
 
mtnbikej said:
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

View attachment 72216

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.
Click to expand...
Wow! That is really awesome J!

As well, it's amazing how fragile a wheel "looks" compared to how strong they really are...
 
Seriously_Tho said:
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 -
Click to expand...

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
 
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
 
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

View attachment 72216



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
 
Ricekrispyota said:
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

View attachment 72216



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.


View attachment 73584
Click to expand...

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.
 
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mtnbikej said:
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 60 kPf 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.
Click to expand...


Solid. Thanks for the info.
 
Three different calculators, three different results :confused:
DT Swiss calculator says Frt left 292mm, Frt right 293mm Rr 293mm
Sapim calculator says Frt left 294mm, Frt right 295mm Rr 295mm
QBP calculator says Frt left 293mm, Frt right 294mm Rr 294mm

Split the difference and go down the middle?

Details for anyone that wants to offer up another opinion.....
Front hub (Boost):
Flange diameter 56mm, center to non drive (disk) flange 26.5mm, center to drive flange 38.0mm, spoke hole diameter 2.5mm
Rear hub (Boost):
Flange diameter 56mm, center to non drive (disk) flange 37.0mm, center to drive flange 37.0mm, spoke hole diameter 2.5mm
Rim:
ERD 595.8mm ETRTO 622x30, symmetrical and no offset for spoke holes.

Using a 14mm nipple (manufacturer recommended)
 
Lost Kiwi said:
Three different calculators, three different results :confused:
DT Swiss calculator says Frt left 292mm, Frt right 293mm Rr 293mm
Sapim calculator says Frt left 294mm, Frt right 295mm Rr 295mm
QBP calculator says Frt left 293mm, Frt right 294mm Rr 294mm

Split the difference and go down the middle?

Details for anyone that wants to offer up another opinion.....
Front hub (Boost):
Flange diameter 56mm, center to non drive (disk) flange 26.5mm, center to drive flange 38.0mm, spoke hole diameter 2.5mm
Rear hub (Boost):
Flange diameter 56mm, center to non drive (disk) flange 37.0mm, center to drive flange 37.0mm, spoke hole diameter 2.5mm
Rim:
ERD 595.8mm ETRTO 622x30, symmetrical and no offset for spoke holes.

Using a 14mm nipple (manufacturer recommended)
Click to expand...


What rim?
 
I am having a consistent issue with one specific spoke breaking every couple of months. Its the second spoke on the drive side forward of the valve stem every time. When I was using aluminum nipples, the head of the nipple would snap off. Now that I have moved to brass nipples, the spoke breaks at the nipple. Spoke tension is measured accurately and is consistent with the rest of the drive side spokes. The spokes are the correct length according to kstoerz.

Also, the spokes are 14ga. I have old wheels and spokes from my other old wheels, that never broke. Those old spokes fit in the 2.16 slot on this tool.
spoke tool.jpg


Do I need to try and find the thicker spokes? Where would I find the 2.16 spokes since I think 13ga will be too big. I'm 250lbs geared up. The wheel is a Stans Flow EX3 with a Hope Pro4 boost hub.
 
That is odd.

When you swapped out the Alloy nipples for Brass, did you swap out the spokes? or are these the originals?

You say the spoke broke at the nipple....how many times? Once, twice, etc.? May have had a damaged spoke from when the nipples broke?

Where is the bottom of the spoke in the nipple when the spoke is tensioned up?

2.0 spokes are fine at your weight.
 
mtnbikej said:
That is odd.

When you swapped out the Alloy nipples for Brass, did you swap out the spokes? or are these the originals?

You say the spoke broke at the nipple....how many times? Once, twice, etc.? May have had a damaged spoke from when the nipples broke?

Where is the bottom of the spoke in the nipple when the spoke is tensioned up?

2.0 spokes are fine at your weight.
Click to expand...


I used the original spokes, and they have all survived fine except the one in that hole. I’m now to the point where I’m putting a new spoke in that hole each time (because I ran out of the old ones). I have broken that specific spoke 8x now (I think)-5 because the nipple broke and 3 because the spoke broke. When the spoke is tensioned up, the threads are not visible at the bottom of the spoke, but the spoke is not “bottomed out”. The end of the spoke sits almost flat with the top of the spoke nipple (if that makes sense).
 
Ricekrispyota said:
I used the original spokes, and they have all survived fine except the one in that hole. I’m now to the point where I’m putting a new spoke in that hole each time (because I ran out of the old ones). I have broken that specific spoke 8x now (I think)-5 because the nipple broke and 3 because the spoke broke. When the spoke is tensioned up, the threads are not visible at the bottom of the spoke, but the spoke is not “bottomed out”. The end of the spoke sits almost flat with the top of the spoke nipple (if that makes sense).
Click to expand...

Which one does it look like?

5TCllor.jpg

nipple-thread.jpg
 
It looks more like the "correct" side, with the spoke thread going to almost the top of the spoke nipple . The green area I have filled in is also spoke thread, extending almost to the bottom of the nipple, but not beyond it. It looked like my spoke broke at the last thread this past weekend. When the nipples broke, I'm pretty sure the spoke was in the "No Go" area, with one or two threads showing. I just find it weird that is has only been that one specific spoke.

nipple-thread.jpg
 
Ricekrispyota said:
It looks more like the "correct" side, with the spoke thread going to almost the top of the spoke nipple . The green area I have filled in is also spoke thread, extending almost to the bottom of the nipple, but not beyond it. It looked like my spoke broke at the last thread this past weekend. When the nipples broke, I'm pretty sure the spoke was in the "No Go" area, with one or two threads showing. I just find it weird that is has only been that one specific spoke.

View attachment 76670
Click to expand...

If that is the case, it sounds like the spoke was threaded too long. If you are seeing threads out of the top of the nipple while the spoke protrudes to almost the end of the nipple, that might be the reason for the spokes breaking....too much threads.

Other than that, I don't know.....kind of a stumper.
 
mtnbikej said:
If that is the case, it sounds like the spoke was threaded too long. If you are seeing threads out of the top of the nipple while the spoke protrudes to almost the end of the nipple, that might be the reason for the spokes breaking....too much threads.

Other than that, I don't know.....kind of a stumper.
Click to expand...


Lol. Cool. Thanks for your input. Ill check each spoke tonight for correct depth, length and tension.
 
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