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Old 06-13-06, 08:39 PM   #1
jimmay
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2x or 3x for Nexus Wheel

Hi all

I am planning to build a 27" 36-hole wheel with a 7-speed Nexus hub for my old touring bike. I have read in a couple of places (Sheldon Brown's site, a spoke site) that wheels with large hubs like Nexus should be built in 2x for better spoke/nipple alignment, but in other places that anything less than 3x doesn't allow transfer of torque from the hub to the rim (I'm no engineer).

Which is correct?
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Old 06-13-06, 08:53 PM   #2
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Originally Posted by jimmay
I am planning to build a 27" 36-hole wheel with a 7-speed Nexus hub for my old touring bike. I have read in a couple of places (Sheldon Brown's site, a spoke site) that wheels with large hubs like Nexus should be built in 2x for better spoke/nipple alignment, but in other places that anything less than 3x doesn't allow transfer of torque from the hub to the rim (I'm no engineer).

Which is correct?
The Nexus 7 isn't all that large. I generally do those cross 3 for a full-size wheel.

The Nexus 8 is larger and I normally do those cross 2.

Sheldon "Playing The Angles" Brown
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Old 06-13-06, 10:35 PM   #3
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With 36 spokes, you won't be getting all that far around the rim anyway. I used to build my track wheels (large flange hubs) with 36 holes 4 cross, and those usually got nicely tengential. I can see not wanting to get the spokes too far around because it would pull at a weird angle, but 36 spokes won't go wrong with 3X even if you're on a Zipp 404 with track hubs... imo of course, Sheldon can ammend as needed.
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Old 06-14-06, 02:04 PM   #4
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There is always a compromise between torque transfer (tangency to the hub would be ideal) and nipple angle at the rim. My default build is 3X, absent a convincing reason to do something else, such as in Sheldon's Nexus 8 example.
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Old 06-14-06, 07:20 PM   #5
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Originally Posted by John E
There is always a compromise between torque transfer (tangency to the hub would be ideal)...
Not so. The "moment arm" is the distance from the centerline of the spoke, perpendicular to the centerline of the axle.

If this distance is too short (as with a wheel with insufficient crossings for the spoke number and flange size) you can have a problem, but beyond a certain point there is no advantage in increasing the distance. This is typically in the range of 2 cm or so.

Sheldon "Enough Is Enough" Brown
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Old 06-14-06, 07:20 PM   #6
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Quote:
Originally Posted by John E
There is always a compromise between torque transfer (tangency to the hub would be ideal)...
Not so. The "moment arm" is the distance from the centerline of the spoke, perpendicular to the centerline of the axle.

If this distance is too short (as with a wheel with insufficient crossings for the spoke number and flange size) you can have a problem, but beyond a certain point there is no advantage in increasing the distance. This is typically in the range of 2 cm or so.

Sheldon "Enough Is Enough" Brown
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