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Old 04-17-14, 09:52 PM   #1
Estuche
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Lacing a 24h hub on a 36h rim???

Hi,
I have a 24h hub to be laced on a 36h rim. Three quick questions:
a) is it a terrible idea (and if so why)?
b) what number should I enter on a spoke length calculator, 24 or 36?
c) what would be the best lacing pattern? It is a 16" (349) front wheel.

Many thanks!
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Old 04-17-14, 11:54 PM   #2
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IMO, it's quite doable. Most 36h rims will survive quite happily with one spoke missing, and to get from 36 to 24 you leave every 3rd hole in the rim empty. I don't think the extra gap will be a problem. There might be some extra soft rims out there though where roundness might become difficult.
Easiest lace is radial. No need to correct the math. I prefer heads-in. Although this might cause the hub flanges to self-destruct unless it's a radial-approved hub and is a definite no-no with hub brakes.
Some standard hubs do fine in radial.
I have a cheat sheet somewhere which lists which builds that come out nicely symmetrical, but off the top of my head I think a cross lace would be difficult. A 24H hub has 15 degrees offset from left to right flange, and a 36h rim has 10 deg spacing. This means that leading and trailing spokes will sit at a slant from the expected path and you'll probably need several different spoke lengths.
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Old 04-18-14, 02:49 AM   #3
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though the other way around 36 hole hub 24 hole rim no un filled rim spoke holes to deal with ..

I suppose 3M reflective tape is useful .. cover the hole and make you visible at night ..


Or .. I'm questioning why not do it properly, buy a 24 hole rim ?

Bike friday uses 24 hole 349 rims , so you can get a rim to match your hub .. ask and they will have spokes too ,

you can use the 36 hole and build strong 36 spoke rear wheel with a 36 hole hub.

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Old 04-18-14, 07:45 AM   #4
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To fill the empty spoke hole in the rim I use nipples turned upside down. First I fill the nipple with the threaded portion of an old, used spoke (spoke end even with the top of the nipple driver slot) and glue them together with epoxy. Then I trim off the rest of the spoke. That gives me a solid nipple. Then I turn it upside down and glue it into the open hole. Never had one come out.
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Old 04-18-14, 01:47 PM   #5
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IMO, it's quite doable. Most 36h rims will survive quite happily with one spoke missing, and to get from 36 to 24 you leave every 3rd hole in the rim empty. I don't think the extra gap will be a problem. There might be some extra soft rims out there though where roundness might become difficult.
The problem with that is that the nipple holes in most rims alternate between angling toward left and right flanges and you'll have radically reduced spoke life if the nipples can't pivot far enough to point at the opposite side.

IIRC Kinlin XR300s are a center-drilled exception.
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Old 04-18-14, 01:53 PM   #6
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I don't think you can use one set of spoke calculations. Because you're skipping holes on the rim but not the hub, the spokes will have three different angles on each side which means three different lengths.
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Old 04-18-14, 02:02 PM   #7
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The problem with that is that the nipple holes in most rims alternate between angling toward left and right flanges and you'll have radically reduced spoke life if the nipples can't pivot far enough to point at the opposite side.

IIRC Kinlin XR300s are a center-drilled exception.
You're right in principle, but if it's actually a problem depends on the rim.
My commuter has a set of wheels that I built with lateral cross on standard Mavic rims and they have done/ are doing just fine.
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Old 04-18-14, 02:08 PM   #8
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You can often get away with more hub holes than rim holes - IMHO it's always best to leave hub holes unfilled instead of rim holes. But this should still work if you are careful and pay attention (build the wheel slowly).

Since you will be skipping every third hole, note that on many rims the holes are offset to match which flange of the hub the spoke is meant to come from. If the holes are offset very much you will have a difficult time truing the wheel - but not impossible.

Definitely go with the radial lacing, run both the 24h & 36h setting on the calculator. If you get any difference (which I doubt) then split it. Best of luck!
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Old 04-18-14, 02:43 PM   #9
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The problem with that is that the nipple holes in most rims alternate between angling toward left and right flanges and you'll have radically reduced spoke life if the nipples can't pivot far enough to point at the opposite side.

IIRC Kinlin XR300s are a center-drilled exception.
Plenty different rims are center drilled.
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Old 04-18-14, 02:47 PM   #10
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I don't think you can use one set of spoke calculations. Because you're skipping holes on the rim but not the hub, the spokes will have three different angles on each side which means three different lengths.
Not sure what you mean. You will have one spoke from each side of the hub than a skip, then another pair and a skip, and so on. Each pair will end up identical to the last and will self adjust to be identical angles and lengths. No problem such as you suggest.
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Old 04-18-14, 03:05 PM   #11
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Not sure what you mean. You will have one spoke from each side of the hub than a skip, then another pair and a skip, and so on. Each pair will end up identical to the last and will self adjust to be identical angles and lengths. No problem such as you suggest.
The holes on the hub which will be used for spokes will be equidistant from each other. The holes on the rim which
are used for spokes will not be equidistant from each other.
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Old 04-18-14, 04:37 PM   #12
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The holes on the hub which will be used for spokes will be equidistant from each other. The holes on the rim which
are used for spokes will not be equidistant from each other.
Doesn't matter. One size spoke will work for every position and give a proper result. It is because of the symmetry. There will be an empty hole on both sides of every pair of spokes. A pair of hub holes will correspond to every pair of occupied rim holes. No problems.
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Old 04-18-14, 06:13 PM   #13
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Doesn't matter. One size spoke will work for every position and give a proper result. It is because of the symmetry. There will be an empty hole on both sides of every pair of spokes. A pair of hub holes will correspond to every pair of occupied rim holes. No problems.
No way. If you put twenty four spokes into a wheel with 36 hole hubs and rims, then they'd be equidistant provided you skip corresponding holes.

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Old 04-18-14, 06:58 PM   #14
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No way. If you put twenty four spokes into a wheel with 36 hole hubs and rims, then they'd be equidistant provided you skip corresponding holes.
I'm sorry, but you are wrong. Every spoke on the left side will be 1/12th the circumference from the next one on that side. Put another way, the 12 spokes on each side will be evenly spaced. Same for the hub holes. Same on the other side. What's the problem? Please note that the spokes may not be perfectly radial in an intended radial pattern, but that's no big deal. The two spkes from opposite sides in each pair will lean toward each other a little. If you cross the spokes, you won't notice this small glitch.
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Old 04-18-14, 08:39 PM   #15
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I'm sorry, but you are wrong. Every spoke on the left side will be 1/12th the circumference from the next one on that side. Put another way, the 12 spokes on each side will be evenly spaced. Same for the hub holes. Same on the other side. What's the problem? Please note that the spokes may not be perfectly radial in an intended radial pattern, but that's no big deal. The two spkes from opposite sides in each pair will lean toward each other a little. If you cross the spokes, you won't notice this small glitch.
Some will be less radial than others.
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Old 04-18-14, 09:37 PM   #16
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Some will be less radial than others.
No, you just don't get it. The hub is fluid in the spoke array and turns to provide a symmetrical alignment of the spokes. The spokes that are paired with one coming from each side will lean slightly toward each other (relative to pure radial) to make up the smaller distance between the 24 hole hub and the 36 hub rim, but every spoke will be offset from radial the same amount. One side will be slightly leading (pointing forward relative to radial) and the other side will be slightly trailing (pointing backward relative to radial). Then you skip a hole in the rim and have the same paired arrangement again, twelve times around the rim. As you tension the spokes evenly the hub will rotate so that all the spokes on one side will point forward just a little but equally and on the other side will point backward the same amount. It all evens out.

Think of two rim holes at 24 hole spacing. Now think of two holes at 36 hole closer spacing in between the 24 spaced holes. If you had a pair of radial spokes in the 24 spaced holes and wanted to move them to the 36 spaced holes, you would have to move them slightly toward each other. That is what is basically happening on the 36 hole rim. The extra empty holes just separate the pairs. If you had a 36 hole bare rim and a built up 24 radial spoke wheel, you could place one over the other and see how it works.
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Old 04-18-14, 09:56 PM   #17
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Hi,
I have a 24h hub to be laced on a 36h rim. Three quick questions:
a) is it a terrible idea (and if so why)?
b) what number should I enter on a spoke length calculator, 24 or 36?
c) what would be the best lacing pattern? It is a 16" (349) front wheel.

Many thanks!
1. yes. Life is too short.
2. see # 1
3. see # 2
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Old 04-18-14, 10:03 PM   #18
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Well all right, maybe for this combination, you're right. I might have been thinking of 20 into 36. However, I still think you should sell the hub or the rim on Ebay, then buy one with the right number of holes.

You may lose a little money but there will be less risk of a screwup and you won't have to explain the extra holes in your rim.

You also won't have to spend time figuring out what spoke length to use.

The offset will provide a slight difference in spoke length because half the spokes will have to go to the wrong holes where offset is concerned.

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Old 04-18-14, 10:59 PM   #19
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b) what number should I enter on a spoke length calculator, 24 or 36?
If you had a center drilled rim, I think running the spoke calculator both ways and then splitting the difference would give a precise result.
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Old 04-19-14, 04:10 AM   #20
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No problems.
Yep.

Here's one side:



The other side will rotate it slightly, putting some torque through the hub, because the hub holes in between the ones on this side don't point exactly to their corresponding holes like this, but NBD.

<2mm different from radial length, I bet.
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Old 04-19-14, 05:52 AM   #21
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Yep.

Here's one side:



The other side will rotate it slightly, putting some torque through the hub, because the hub holes in between the ones on this side don't point exactly to their corresponding holes like this, but NBD.

<2mm different from radial length, I bet.
When you do the other side with the same length spokes, both sides are turned. Then neither side points exactly to the corresponding holes. It is just the same as when you are doing a cross pattern. You start out with the spokes loosely radial, then twist the hub to get the tangent spoke line. Then you lock that in with the opposite direction spokes. There will be no cross in this case, but the same mechanism is operating. The same length spokes on the second side twists the hub and locks in a symmetrical pattern that is the same (but opposite) on both sides. Thanks for the diagram.
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Old 04-19-14, 09:51 PM   #22
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Thank you for your helpful responses!!!
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Old 07-09-14, 10:41 AM   #23
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Hi Again, just wondering if the same principle applies to 16h hubs with 24h rims?
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Old 07-09-14, 12:17 PM   #24
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Yea, Get another hub to go with the rim hole count..


Bike friday Builds 24 spoke 349 rim wheels on their Tikits .



I used to own an early Mk2 Brompton,, they built a 20 spoke wheel for the front..

now both are 28..

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Old 07-09-14, 12:27 PM   #25
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Hmmm. Front or rear? What would you consider to be a fair trade for your 24 hole hub?
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