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Converted Marathon Runner
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Discussion Starter #1
Having ventured into building wheels about 1.5 years ago, I'm getting to the point that I want to go exotic here and there. Usually, I just tinker with radial lacing or lighter spokes, different crossing patterns, etc.

I was going through my box of parts at home, and found a set of Speedcific Hubs, in a 28h drilling that came from a previous set of hoops.

Since they are very light, I'd like to use them in a build with something very light for a rim, or something "cool". Most of the latter are in 20h/24h drillings (Zipp carbons for example), and I got to wondering if I can use a 28h hub on a 20h, or a 24h rim, and if so, how?

Do spoke lengths change? How is it done? Is it possible?

Thanks in advance.

10k
 

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wheelbuilder
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10kman said:
Having ventured into building wheels about 1.5 years ago, I'm getting to the point that I want to go exotic here and there. Usually, I just tinker with radial lacing or lighter spokes, different crossing patterns, etc.

I was going through my box of parts at home, and found a set of Speedcific Hubs, in a 28h drilling that came from a previous set of hoops.

Since they are very light, I'd like to use them in a build with something very light for a rim, or something "cool". Most of the latter are in 20h/24h drillings (Zipp carbons for example), and I got to wondering if I can use a 28h hub on a 20h, or a 24h rim, and if so, how?

Do spoke lengths change? How is it done? Is it possible?

Thanks in advance.

10k
You might end up building the wheels more than once if you get the lengths wrong. You can get Zipp rims in almost any spoke count you want. If you are getting new rims, you gain nothing by fitting a square peg into a round hole. Just get 28 hole rims.
 

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Converted Marathon Runner
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Discussion Starter #3
I know....

I know that much, I am more curious if it's possible to do, and if so, how.......
 

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Possible, and pointless

10kman said:
I know that much, I am more curious if it's possible to do, and if so, how.......
yes, it is possible to spoke any number of spokes with any hub and any rim. No point to it, and you can end up with very uneven spoke-to-spoke tensionn and several different spoke lengths. This makes for a confusing build, a potentially unstable (or at least weaker) wheel, more difficult maintenance, and no performance improvement. Knock yourself out!
 

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10kman said:
Most of the latter are in 20h/24h drillings (Zipp carbons for example), and I got to wondering if I can use a 28h hub on a 20h, or a 24h rim, and if so, how?

Do spoke lengths change? How is it done? Is it possible?
The others have covered the more-headache-than-its-worth category well. But if you really must try, then the first step is figuring out some type of pattern of the spokes that will balance the torque between the right and left flanges. Remember that the static tension of spokes pulling at angle from the flange will create a torque reaction at the flange. However, in most conventional lacing patterns, there are equal number of spokes pulling at equal and opposite angles on each flange, so there is no net torque on each flange.

Once you have figured out the lacing patterns, you can derive the angles of each spoke. The angles can then be used in the standard spoke length formula:

L = squareroot( A^2 + B^2 + C^2) - (S/2)

A = (D - d x cos( theta) ) / 2
B = d x sin(theta) / 2
C = w

L = Spoke length
D = Effective rim diameter
d = Diameter of flange spoke holes
w = Flange offset (from center of hub)
S = Spoke hole diameter
theta = spoke angle at flange (radial = 0 deg.)
 

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Converted Marathon Runner
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Discussion Starter #6
Thank you....

Thanks for the description. That's what I was looking for. I'm aware of the headache involved, and was more curious if it was possible to do and also, reliable. Obviously, there's no way a rig job can stand up to a real solution, but I still want to know just for the sake of knowing.

Take care,

10k
 

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Resident Dutchbag
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It's feasable to do with hubs, a German wheelbuilder does quite a lot with it and has good reputation. They use their own custom drilled rims to fit.

 

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wheelbuilder
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rogger said:
It's feasable to do with hubs, a German wheelbuilder does quite a lot with it and has good reputation. They use their own custom drilled rims to fit.
Damn that looks nice. I'd to see a few more pics and a link to see more. I like the details. Heads in and bladed spokes to make the cross easier. Nice touch.

-Eric
 

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Resident Dutchbag
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Ligero said:
I have built a 32h front hub into a 28h rim and it was not easy or did it turn out all that well. I do skip every other hole on the rear sometimes.
Have you ever done a rear wheel (say a 32) with 16 spokes on the drive side and 8 on the other? That would at least make some sense to me since it would help equalize the tension with a standard rim.
 

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Yes, I have done a rear wheels that way and would do it on more wheels but it requires a very stiff rim to work good and a lot of the lightweight rims that are out are not stiff enough. The picture above is also laced that way but with 12 drive side and 6 non drive side.
 

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SDizzle said:
I can't believe they can offer any kind of a warranty on most of those. Seriously - take a 36h hub that's not OK'd for radial lacing, and then radial lace it, skipping every other hole? Hmmm...
They offer 3 years on spokes and an indefinite period where parts are replaced on basis of fairness. I also hang out on a major German bike forum and I don't think I've read anything negative about them.
 

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Roadie with unshaven legs
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I've been working out the details of doing something simple when it comes to skipping spokes: 36 hole hub laced to a 24 hole rim, lacing two consecutive holes then skipping one like in the picture above. The problem is that the offset of the spoke holes on one flange of the hub compared to the other one is enough to cause a slight torque to the hub center. In other words, one flange is being pulled one way and the other flange is pulled the other way, twisting in the middle. The spokes need to be two different lengths, I'm not sure what the differences in length are.

For lacing a wheel with different spoke counts on one side compared to the other side, what about the area between where two spokes are from the same flange attach without a balancing spoke from the other flange? You need a really stiff rim to accomodate this (Ligero mentioned). I wouldn't do it.
 

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Squidward said:
The problem is that the offset of the spoke holes on one flange of the hub compared to the other one is enough to cause a slight torque to the hub center. In other words, one flange is being pulled one way and the other flange is pulled the other way, twisting in the middle. The spokes need to be two different lengths, I'm not sure what the differences in length are.
Try it with a 36 hole rim.
 
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