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28 spoke 3 cross hub flange diameter and rim depth

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28 spoke 3 cross hub flange diameter and rim depth

Old 07-06-16, 08:28 PM
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28 spoke 3 cross hub flange diameter and rim depth

Like the title says:

Theoretically, 3x is mathematically possible with 28 spokes. However, hub flange diameter and rim depth will limit this. At a certain size, only 2x will be possible.

Any idea on what that might be? My spoke calculator doesn't provide that little piece of data.
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Old 07-06-16, 08:45 PM
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A coarse rule of thumb is that spoke separation st the hub sho8ule be less than at the rim. So as long as the flange is smaller than about 2/3rds the distance between 2 spoke holes on the same side (or hole/skip/hole) you'll be fine building 3x/28.

Of course it really depends on the amount of nipple float in the rim, so if you want something better than a rule of thumb and have the rim in hand, you can do better. Thread two spokes and nipples into the rim (skip one hole), pull down to apply a bit of tension and spread apart at the hub end to see how far the nipples can follow. The point a which the nipple resists and the spoke wants to bend at the nipple is the limit. If that's beyond the flange diameter you're good to go, if not, reduce the cross.
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Old 07-07-16, 05:36 AM
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Originally Posted by FBinNY
A coarse rule of thumb is that spoke separation st the hub sho8ule be less than at the rim. So as long as the flange is smaller than about 2/3rds the distance between 2 spoke holes on the same side (or hole/skip/hole) you'll be fine building 3x/28.

Of course it really depends on the amount of nipple float in the rim, so if you want something better than a rule of thumb and have the rim in hand, you can do better. Thread two spokes and nipples into the rim (skip one hole), pull down to apply a bit of tension and spread apart at the hub end to see how far the nipples can follow. The point a which the nipple resists and the spoke wants to bend at the nipple is the limit. If that's beyond the flange diameter you're good to go, if not, reduce the cross.
This is very good information; I find, for example, that Sapim nipples allow for a more acute angle at the rim than DT's nipples.
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Old 07-07-16, 08:22 AM
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3_X, 32 hole, the first cross is the nearest spoke on the hub flange going to the opposite rim edge.

My World Tour Rohloff was laced like that in an attempt to make it most durable.

In that, its like 4 cross 36 hole , and 5 cross 48 hole.

spoke pull is compressing the metal between the holes, so tear out is quite unlikely.

radial spoking, is the opposite .

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Old 07-07-16, 09:39 AM
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Originally Posted by FBinNY
A coarse rule of thumb is that spoke separation st the hub sho8ule be less than at the rim. So as long as the flange is smaller than about 2/3rds the distance between 2 spoke holes on the same side (or hole/skip/hole) you'll be fine building 3x/28.

Of course it really depends on the amount of nipple float in the rim, so if you want something better than a rule of thumb and have the rim in hand, you can do better. Thread two spokes and nipples into the rim (skip one hole), pull down to apply a bit of tension and spread apart at the hub end to see how far the nipples can follow. The point a which the nipple resists and the spoke wants to bend at the nipple is the limit. If that's beyond the flange diameter you're good to go, if not, reduce the cross.
Thanks for the info. Tough to test without the parts in hand, though measurements are easy enough if applying the above wag.

I'll just throw the plan out there: Dura Ace rear hub, 28h, laced 3x to pacenti sl23 rim.

Think 3x will work?
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Old 07-07-16, 10:20 AM
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On any small flange hub, the difference between tangent and secant (1 fewer cross) is very small. So it's always safe to build full tangent. This is the kind of question that only arises with larger flanges.

It might also arise on a deep 20" rim where spoke angle becomes unusually critical.
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Old 07-07-16, 11:15 AM
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You only 110 pounds or less?
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Old 07-07-16, 11:28 AM
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140. I don't see weight being a huge issue for 28 spokes. I've ridden less with no issues, but I generally do prefer 32 rear, 28 front.

Otherwise, it sounds like 3x will work on this hub/rim combo.
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Old 07-07-16, 12:10 PM
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Originally Posted by fietsbob
You only 110 pounds or less?
I weigh shy of 200#s and routinely ride 32h wheels built with very light rims and spokes with no issue. I've also built light 36h tandem wheels and sent then across the country with no issues.

There's plenty of reserve strength in a well built 28h wheel for riders well over 160#s, and probably as much as 200.

In any case, when people come to the forum with a very specific question on a detail, we should endeavor to provide that answer rather than some generalized lecture about the wisdom of their general decision. If the OP wanted to know if a 28h wheel was OK for his purpose, that's what he would have asked.
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Old 07-07-16, 12:33 PM
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Time trial wheels?



My 28 hole wheels are smaller , but even though a 349 rim the rear Brompton wheel has like 12 gage spokes.

Front. New SON XS is DB 14ga.

My Burly trailer has 28 spoke 406 rims ...
28 hole rear wheel for like a bike friday or other folding bike it would be great.

low spoke count 700c Race bike wheels need more careful use and care IMO, as 1 broken spoke lets a lot more rim flex
out of true and more likely warped rim. that needs a higher tension to pull back in shape.

Good Luck.

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Old 07-07-16, 01:24 PM
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Yes, thank you.

I'm not looking for thoughts on the weight, just the spoke crossing.

I've built many wheels, so not a novice. Enough to know that my plan might have issues, but might not. Since my calculator can't model the crossings (it merely does the math on length and angle...I'm sure it will spit out numbers for 28 spoke 4x if I plugged that in), I was merely looking for some fidelity on it before making purchases.

Stinks to get a bunch of parts in the mail, to find that they don't work for you.
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