Help needed from wheelbuilders for 24 spokes on 36 hole hub.

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bricky21
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Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

rruff wrote:There are many patterns you can make with 10 or 14 spokes on each side. I'd avoid ones that have groupings of 3 in a row though... 2 is pushing it.

You also need to think about heads-in and heads-out and where the cross will occur, etc.


Yes I'm seeing that, but it seems that regardless of the combination I choose everything will revolve around 4 crows foot patterns(2 on each side) with my only real options being the spoke tangents.

I wanted to get heads in all the way around on both sides, but after doing a couple of drawings and using a 36 hole crows foot laced wheel I have as a reference I've come to the conclusion that it's not really possible without seriously modifying the spokes.

I've settled on a design that creates the best tangents while keeping the design symmetrical. I believe this design is sound...do you see anything that could be changed to make it better?

All these drawing are viewed as if you're looking at them from the drive side ie freehub closest to you.

NDS yellow spokes are heads in red spokes are heads out
final rear nds Y=hd's in R=Hd's out.JPG


DS Green spokes are heads in Blue spokes are heads out
final G=Hd's in B=Hd's out.JPG


Complete wheel Green & Yellow heads in Blue & Red heads out
Rear wheel scaled down.JPG


Also, will I be able to use a spoke calculator to figure these lengths or will I need to do it on paper?

rruff
Shop Owner
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by rruff

bricky21 wrote:I've settled on a design that creates the best tangents while keeping the design symmetrical. I believe this design is sound...do you see anything that could be changed to make it better? Also, will I be able to use a spoke calculator to figure these lengths or will I need to do it on paper?


I don't see any issues.

You might as well start with first principals, and check to make sure you understand and are accurate with standard lacings first... which you can check against other calculators.

by Weenie


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cryoplasm

by cryoplasm

Those patterns are not symmetric.

By a symmetric wheel, you want to have it "symmetric" however much you rotate the wheel. That's the entire definition of a wheel.

The front is easy. For the rear, you want the NDS and DS flanges running in phase with the rim. Such that no matter how much you turn and look at the wheel it is "symmetric".

rruff
Shop Owner
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by rruff

Why?

bricky21
Posts: 1403
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

cryoplasm wrote:Those patterns are not symmetric.

By a symmetric wheel, you want to have it "symmetric" however much you rotate the wheel. That's the entire definition of a wheel.

The front is easy. For the rear, you want the NDS and DS flanges running in phase with the rim. Such that no matter how much you turn and look at the wheel it is "symmetric".


What I meant was that each spoke grouping is centered between the hub and rim.

cryoplasm

by cryoplasm

This is a binary permutation of your 10/14 pattern.

Image

There is an overlapping to 2:5 spoke ratio which is not symmetric at the hub. In fact there is no way it can be symmetric in this configuration. The goal should be to offset the load from the DS to the NDS evenly which this configuration will not do. It defeats the purpose of the configuration calling into question the entire purpose of the 10/14 pattern. If you carry on what you'll get is a wheel which is nonuniform (you may build it round/true). There is more to uniformity than simply true-ness. It will most certainly be an unpredictable wheel lacking in durability. You'll be wasting resources in building something this unsound.

There a number of aspects to a symmetric wheel. The main aim is to have a wheel which no matter how much you turn it, the wheel still looks the same. Don't dismiss the example I provided earlier.

bricky21
Posts: 1403
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

Ok, I think I've come up with something better. It's a 12-12 design that I think very well balanced having the drive side in a two cross pattern and the non drive side with 6 crossed spokes and 6 radial. On the complete wheel I spread out the crossed spokes on the NDS to give a better angle.

NDS.JPG

DS.JPG

complete with SAA.JPG

rruff
Shop Owner
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Location: Alto, NM

by rruff

cryoplasm wrote:The goal should be to offset the load from the DS to the NDS evenly which this configuration will not do. It defeats the purpose of the configuration calling into question the entire purpose of the 10/14 pattern.


The "purpose" is to do a build that is torsionally neutral, and has spoke lengths that are easily determined. Of of course it isn't balanced... and you need a stiff rim. But having 3 DS spokes in a row would cause more problems.

rruff
Shop Owner
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Joined: Sun Jan 08, 2006 9:12 am
Location: Alto, NM

by rruff

bricky21 wrote:Ok, I think I've come up with something better. It's a 12-12 design that I think very well balanced having the drive side in a two cross pattern and the non drive side with 6 crossed spokes and 6 radial. On the complete wheel I spread out the crossed spokes on the NDS to give a better angle.


Hey, that looks like a good one! Certainly the best I've seen. I didn't realize you could make a good pattern on each side with 12-12. I guess it is like Rinards, but with some of the NDS spokes crossed. It actually would be easier to make them more radial like he did... you might have extreme bends where the spokes cross.

cryoplasm

by cryoplasm

rruff wrote:The "purpose" is to do a build that is torsionally neutral, and has spoke lengths that are easily determined. Of of course it isn't balanced... and you need a stiff rim.


Calculating spoke lengths isn't the problem whatsoever. They can be simple or complicated to calculate, it doesn't matter. The wheel needs to be built right. If it isn't balanced, don't bother.


rruff wrote:But having 3 DS spokes in a row would cause more problems.


3:1 ratio of DS to NDS, and no dodgy overlaps. This would produce an even wheel.

bricky21
Posts: 1403
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

rruff wrote: you might have extreme bends where the spokes cross.


That is something I have been concerned about. I laid out the pattern on the floor with some spare Cx-Ray's I have lying around and it looks like if I can get a hold of one's with a shorter round section(hope that makes sense) I'll be OK. I've use Cx-Ray's several times and have noticed that they're not very consistent in the length of the butting, so hopefully if I explain the situation to whomever I buy the spokes from they'll help me out and send some that will work.

rruff
Shop Owner
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Location: Alto, NM

by rruff

cryoplasm wrote:3:1 ratio of DS to NDS, and no dodgy overlaps. This would produce an even wheel.


But a weak one.

rruff
Shop Owner
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Joined: Sun Jan 08, 2006 9:12 am
Location: Alto, NM

by rruff

bricky21 wrote:if I can get a hold of one's with a shorter round section(hope that makes sense) I'll be OK.


Alchemy might need to roll/cut longer spokes but they have done this for me before.

EDIT: you can also have the crossed spokes originate farther apart on the hub.

bricky21
Posts: 1403
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

rruff wrote:EDIT: you can also have the crossed spokes originate farther apart on the hub.


In the last drawing I spaced them as far apart as possible without creating a whole different set of problems.

I built a set of 36 hole wheels with crows foot DS on Dura Ace hubs and there was plenty of room... the 24 hole rim is gonna increase the spoke angle and bring the crossings closer to the flange, but with a little bit of luck I think I'll be make it. I'll call Alchemy and see what my options are.

cryoplasm

by cryoplasm

rruff wrote:
cryoplasm wrote:3:1 ratio of DS to NDS, and no dodgy overlaps. This would produce an even wheel.


But a weak one.


No a stronger one.

As I pointed out earlier, you've got multiple overlaps of spoke ratios in the 10/14 example. The resulting nonuniform wheel has both weak and strong spots which are in irregular formation. You can't say this design is overall stronger.

I further suggested a cross pattern on the DS. The wheel would have a symmetric spoke ratio (3:1 throughout) with further load offset by the cross pattern which is also in a regular pattern.
One may bolster the wheel further by deciding on choice of spoke.

You may argue too few spokes on the NDS but the arising issue can be worked out from an engineering standpoint. Giving special consideration to this problem it's about choosing the least worst option. If you're going to build a wheel, aim to ensure the properties of a wheel are preserved. Needless to say, the ideal combination of rim to hub lies elsewhere. And it isn't necessarily a 24 spoke count either.

by Weenie


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