# 24h rim, 32h hub...



## Joe Connell (Jul 31, 2002)

I'd like to build a rear wheel like this, it should balance out spoke tension. (16 drive side spokes, 8 non drive side). Has anyone built one? Here are my questions:

1) How do you calculate the spoke lengths? 
2) I'd guess radial is the way to go on the non drive side, but for drive side, you'd have to use 2x, right, but how much extra length do you need?
3) How was the build up? I'd like picutres if you have them

Thanks,
Joe


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## Fogdweller (Mar 26, 2004)

This topic comes up about every two months and my answer is always the same: The flange is not designed to handle these tensions and these wheels almost always fail. Buy a rim to match the hub or a hub to match the rim but don't attempt to fuse different hole counts. Seriously, this is not worth the risk.


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## Mark McM (Jun 18, 2005)

*Triplet lacing*



Joe Connell said:


> I'd like to build a rear wheel like this, it should balance out spoke tension. (16 drive side spokes, 8 non drive side). Has anyone built one? Here are my questions:
> 
> 1) How do you calculate the spoke lengths?
> 2) I'd guess radial is the way to go on the non drive side, but for drive side, you'd have to use 2x, right, but how much extra length do you need?
> 3) How was the build up? I'd like picutres if you have them


I've built a few. Calculating the spoke lengths is largely the same as for any other wheel. The difference is figuring out the spoke angles. This is most easily done by graphing out the lacing pattern.

As you say, for a triplet pattern to match a 32 hole hub to a 24 hole rim, the most common pattern is to use all the right flange spoke holes (16) and every other left flange spoke holes. For the right spokes, you have a choice of lacing 2X or 3X. For a 2X pattern, the spoke angle is 48.75 degrees, and for a 3X pattern, the angle is 63.75 degrees. For the left side, you have choice between radial, 1X or 2X. For radial, the angle is 0 degrees (obviously), for a 1X pattern, the angle is 45 degrees, and for 2X, the angle is 90 degrees. The last such wheel I built, I used 3X on the right side, and 2X on the left side.

You probably already realize this, but a major caveat is that you must use a very rigid rim for this lacing pattern. Because there is a long span with two right pulling spokes between the left pulling spokes, if the rim isn't rigid enough, you'll end up with a very wavy shaped wheel.


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## Joe Connell (Jul 31, 2002)

Mark McM said:


> I've built a few. Calculating the spoke lengths is largely the same as for any other wheel. The difference is figuring out the spoke angles. This is most easily done by graphing out the lacing pattern.
> 
> As you say, for a triplet pattern to match a 32 hole hub to a 24 hole rim, the most common pattern is to use all the right flange spoke holes (16) and every other left flange spoke holes. For the right spokes, you have a choice of lacing 2X or 3X. For a 2X pattern, the spoke angle is 48.75 degrees, and for a 3X pattern, the angle is 63.75 degrees. For the left side, you have choice between radial, 1X or 2X. For radial, the angle is 0 degrees (obviously), for a 1X pattern, the angle is 45 degrees, and for 2X, the angle is 90 degrees. The last such wheel I built, I used 3X on the right side, and 2X on the left side.
> 
> You probably already realize this, but a major caveat is that you must use a very rigid rim for this lacing pattern. Because there is a long span with two right pulling spokes between the left pulling spokes, if the rim isn't rigid enough, you'll end up with a very wavy shaped wheel.




This came up because I got frusterated with the machine built wheels I recieved with my bike. My nicer wheels are ok, but the cheap wheelset I got with my bike wasn't tightened enough, and now I'm breaking left side spokes (I could re-lace the wheel, but I'd rather do something more creative). I'll start with a deep-v, or one of the other semi aero clincher rims and go from there. I've built three or four wheelsets in my day and the only problems I have with those wheels are when I pick up a stick, otherwise they stay true and don't break. I've also used the off center wheels for my mountain bikes, but I figured on the road, something a little more intresting would work. 

For the 3X, I figured the spokes would hit the hubs, and I worried about that (that's why I was thinking 2X), I'd rather do 3X if I can on the right side, and 1X on the left side would be best I think. 

How are the wheels holding up? I'd like to see pictures if you have them to see how you laced them. I'm having a hard time understanding how I'd overstress the hub though, when I build my wheels I really ratchet up the tension, and I havn't had an issue with hub breakage, and the hubs are the same thickness on both sides, meaning they should be able to handle the same tension.

Thanks,
Joe


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## rruff (Feb 28, 2006)

Joe Connell said:


> I'd like to build a rear wheel like this, it should balance out spoke tension. (16 drive side spokes, 8 non drive side). Has anyone built one?


I haven't, but I will the next time I need a new wheel. I'd use a 32 hole rim, though... that way it is very simple and all the spokes can be the same length... on each side that is. You will also not have the issue of spokes exiting the rim from the wrong direction for 4 of the spokes on the drive side. You just skip every other spoke on the ND side... radial lacing heads in would improve the lateral stiffness a bit. Do 3x on the drive side.

A Deep V should work fine...


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## rruff (Feb 28, 2006)

Fogdweller said:


> The flange is not designed to handle these tensions and these wheels almost always fail.


Any actual experience? Seems to me that the ND flange should easily be able to handle the same spoke tension as all the others (the tension will be about the same as the drive side)... especially when only half the holes are being used.


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## Marc (Jan 23, 2005)

Fogdweller said:


> This topic comes up about every two months and my answer is always the same: The flange is not designed to handle these tensions and these wheels almost always fail. Buy a rim to match the hub or a hub to match the rim but don't attempt to fuse different hole counts. Seriously, this is not worth the risk.


Agreed. Don't do it.


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## eddie m (Jul 6, 2002)

Campy G3 wheels are spoked with twice as many spokes on the drive side, but the rims are drilled so that 2 drive side and 1 non-drive side spoke all attach close together, with a long space between the groups of 3, sort of like a Rolf paired spoke wheel. I don't think I'd build a wheel that way unless I could get a rim that was drilled like the Campy G3 rims. I don't think the hub will be a problem, but the rim might bend laterally too much. You could try it with radial spoking, and if you didn't like it you could add the rest of the spokes later.
For rims with equally spaced holes, I think the best choice is to use a lighter guage spoke on the left side, but spoke it the same way as the drive side. That gives you a more reliable wheel because the light guage spokes stretch so much that they never go slack. 

em


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## Fogdweller (Mar 26, 2004)

rruff said:


> Any actual experience? Seems to me that the ND flange should easily be able to handle the same spoke tension as all the others (the tension will be about the same as the drive side)... especially when only half the holes are being used.


I've seen failures of this sort, yes, and had a similar experience myself. I've never built a wheel personally in this configuration for the reasons I gave. D/ND tension is collective, meaning that a side's work load distributed evenly among the spokes. The collective tension of the ND spokes must equal that of the drive spokes but since there are few of them, the force put on the flange where the spoke head is connecting is increased. Increased beyond what the flange was designed for? How should I know, but is it really worth the risk?

The only personal experience I've had was radial lacing a record front hub back in the early 80s. I built it for a time trial bike but the flange was designed for 3 and 4 cross. It eventually failed at two spokes because the direction of the force was on a radius rather than at an angle. That was with correct tensioning on a complete compliment of spokes. I pass posting on a lot of threads but never on this topic. Chris King wouldn't either.


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## eddie m (Jul 6, 2002)

Fogdweller said:


> I've seen failures of this sort, yes, and had a similar experience myself. I've never built a wheel personally in this configuration for the reasons I gave. D/ND tension is collective, meaning that a side's work load distributed evenly among the spokes. The collective tension of the ND spokes must equal that of the drive spokes but since there are few of them, the force put on the flange where the spoke head is connecting is increased. Increased beyond what the flange was designed for? How should I know, but is it really worth the risk?.


The "collective tension" of the left spokes is much less than the tension of the right side spokes. The force in each spoke is a vector that can be resolved into a radial and an axial component. The some of the axial components of the left side equals the sum of the axial components of the right side (but in the opposite direction), but because the staying angle of each side is so different, the left side spokes exert much less force in the radial direction. That's why the left side spokes have much less total tension, which is obvious to anyone who has ever built a wheel. Left side spokes often fail because they have too little tension, which allows them to go slack, leading to early fatigue failure. It makes sense to use lighter guage spokes on the left side, or to equalize tension in each spoke by using fewer spokes on the left side.
As far as hub failure goes, even if you use half the spokes on the left side, each spoke will still have about the same tension as the right side spokes, so it doesn't seem like a flange failure should be a problem.
The rim is a different issue. With equally spaced spokes there is a significant lateral bending moment in the rim. Pairing the spokes (as in a Rolf wheel) or grouping them closely in groups of 3 (as in a Campy G3 wheel) minimizes the bending moment. That leaves a pretty long span between groups of spokes, and probably makes the wheel a little more susceptible to impact damage, but it doesn't hurt the wheel's static strength a bit.

em


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## rruff (Feb 28, 2006)

Fogdweller said:


> The collective tension of the ND spokes must equal that of the drive spokes


That isn't true. The thing that must balance is the collective tension x bracing angle. Since the bracing angle is ~ double on the ND side the *tension* on both sides would end up being about the same... instead of the ND side being about half the tension in a normal wheel. Also, since only half the spoke holes in the hub are used the collective tension on the hub is still only half what it is on the drive side. 

The next argument you make is about having a failure when you radial laced an old Campy front hub that wasn't designed for it... really, that isn't relevent.


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## Joe Connell (Jul 31, 2002)

We'll see how it works out, if nothing else, it's a $50 experement. There may be more tension in the left side hub, and that may cause a problem. I'll know more when I build it.

Joe



eddie m said:


> The "collective tension" of the left spokes is much less than the tension of the right side spokes. The force in each spoke is a vector that can be resolved into a radial and an axial component. The some of the axial components of the left side equals the sum of the axial components of the right side (but in the opposite direction), but because the staying angle of each side is so different, the left side spokes exert much less force in the radial direction. That's why the left side spokes have much less total tension, which is obvious to anyone who has ever built a wheel. Left side spokes often fail because they have too little tension, which allows them to go slack, leading to early fatigue failure. It makes sense to use lighter guage spokes on the left side, or to equalize tension in each spoke by using fewer spokes on the left side.
> As far as hub failure goes, even if you use half the spokes on the left side, each spoke will still have about the same tension as the right side spokes, so it doesn't seem like a flange failure should be a problem.
> The rim is a different issue. With equally spaced spokes there is a significant lateral bending moment in the rim. Pairing the spokes (as in a Rolf wheel) or grouping them closely in groups of 3 (as in a Campy G3 wheel) minimizes the bending moment. That leaves a pretty long span between groups of spokes, and probably makes the wheel a little more susceptible to impact damage, but it doesn't hurt the wheel's static strength a bit.
> 
> em


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## Fogdweller (Mar 26, 2004)

rruff said:


> really, that isn't relevent.


I think it is, at least it's more relevant than your "Seems to me..." response. The fact remains, regardless of spoke tension, the force on each hole of the flange will double and you don't even know what kind of hub it is, only that it's 32 hole.

You're messing with a topic that could get someone seriously hurt but all you can do is poke holes in my post. Does the well-being of the OPer concern you in the slightest?


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## Joe Connell (Jul 31, 2002)

Thank you for your concern. I will pay attention to the wheel and discontinue it if I see any issues.



Fogdweller said:


> I think it is, at least it's more relevant than your "Seems to me..." response. The fact remains, regardless of spoke tension, the force on each hole of the flange will double and you don't even know what kind of hub it is, only that it's 32 hole.
> 
> You're messing with a topic that could get someone seriously hurt but all you can do is poke holes in my post. Does the well-being of the OPer concern you in the slightest?


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## Ligero (Oct 21, 2005)

I build 32h hubs into 24h rims all the time. As long as the rim is stiff enough it makes a very nice rear wheel. I do 3x on the drive side and 1x on the non drive side. The wheel in the picture all of the drive spokes are at 120nm and all of the non drive are at 115nm.


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## Joe Connell (Jul 31, 2002)

Thanks! Looks like it should work out well, and the spoke tension should balance out well, and should make a long lasting wheel.

Joe



Ligero said:


> I build 32h hubs into 24h rims all the time. As long as the rim is stiff enough it makes a very nice rear wheel. I do 3x on the drive side and 1x on the non drive side. The wheel in the picture all of the drive spokes are at 120nm and all of the non drive are at 115nm.


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## rruff (Feb 28, 2006)

Ligero said:


> I build 32h hubs into 24h rims all the time..


Do you do anything special with the 4 rim holes that are not going the right direction?


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## Ligero (Oct 21, 2005)

rruff said:


> Do you do anything special with the 4 rim holes that are not going the right direction?


I only do it on rims that are drilled on center and do not have the spoke holes drilled offset. I also do it on Zipp rims even though they are drilled offset, there drilling is so bad you have to file the holes to get them straight so I can just file them to angle any way I want.


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## terzo rene (Mar 23, 2002)

Ligero said:


> I only do it on rims that are drilled on center and do not have the spoke holes drilled offset. I also do it on Zipp rims even though they are drilled offset, there drilling is so bad you have to file the holes to get them straight so I can just file them to angle any way I want.


 I wish I had thought of that before I trashed a 250 rim with the cross angled triplet spokes last year (but Zipp did surprise me by replacing it for free).

Other than that I have done a number of triplet laced rear wheels with no issues. I really like them and feel a triplet 24 is generally a stiffer better wheel than a traditional 28 spoke with the same components. To calculate spoke length use 3.33 crosses/32 spokes when calculating the drive side length for 3x, non drive just use 16 spoke and 2X (or whatever you want to do) to calculate.

I know Dave Thomas at Speeddream has been building triplet laced for years, before that Hi-E wheels were also laced that way, so at least with a stiff rim and quality hubs the durability concerns are way overblown. I have even done 2X drive, 1X non-drive triplet with no flange problems.


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## -dustin (Jan 11, 2009)

terzo rene said:


> To calculate spoke length use 3.33 crosses/32 spokes when calculating the drive side length for 3x, non drive just use 16 spoke and 2X (or whatever you want to do) to calculate.





Mark McM said:


> I
> As you say, for a triplet pattern to match a 32 hole hub to a 24 hole rim, the most common pattern is to use all the right flange spoke holes (16) and every other left flange spoke holes. For the right spokes, you have a choice of lacing 2X or 3X. For a 2X pattern, the spoke angle is 48.75 degrees, and for a 3X pattern, the angle is 63.75 degrees. For the left side, you have choice between radial, 1X or 2X. For radial, the angle is 0 degrees (obviously), for a 1X pattern, the angle is 45 degrees, and for 2X, the angle is 90 degrees. The last such wheel I built, I used 3X on the right side, and 2X on the left side.


Can someone draw me a diagram? Seriously. I don't understand where these numbers (3.33, 63.75, etc) are coming from. 

Tomorrow I will be building up a (or making an attempt at) Blackwell 100 with a Powertap (24/ 32h). I thought I had my driveside spoke lengths figured out, but these posts have me questioning myself.


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## FORT-Cyclist (Jan 19, 2003)

I did it with an Ultegra hub and a Fulcrum Racing 7 rim:








CX-Rays are best for this because they cross at their flat parts.
Spokes on the left side with circular cross sections bend to sharp at the crossing point.
This Ultegra hub is not made for radial lacing with only 8 spokes on the left side.
I tried it and flange bulged outwards at the relevant holes.

You have to make sure that the spokes on the left side give enough lateral stiffness otherwise the right spokes pull the rim over.
Therefore you need a hub having the left flange far out (current Ultegras, 105s, Campagnolo).
Lacing with spoke heads inwards increases lateral stiffness; too.
If you chose 2x lacing on the left side, you might need thicker spokes on left side than on the right side.


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