Bicycle Mechanics - Wheelbuilding and spoke patterns
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04-16-12, 11:15 AM
According to Shimano, rear hub brake wheels should be built asymmetrically. The only answer I've ever got from anyone about this is that it somehow serves to equalize the forces when braking. Does anyone know anything about this? It seems like something that should make sense.
Also, I have also been told that wheels which are subject to torque (rear wheels, front hub brake wheels) can be built crossed on one side and radial on the other. Are hub shells really so lacking in stiffness that the non-drive/non-brake spokes don't really do anything? Even if they are subject to less force (and are not under as much tension) than the drive/brake spokes, won't they still contribute, and won't it build a more durable wheel if they are all crossed?
Furthermore, why build 1x or 2x, other than to "save weight"?
04-16-12, 11:25 AM
Rather determine if all-inside-pulling OR all-outside pulling will result in the NDS spokes arranged the way they want it.
Whichever one it is...do it.
Keep in mind though, even with the wrong lacing BUT properly tensioned and stress relieved the wheel will be fine...
No need to experiment...just go 3x...go symmetrical with the disc side the way they want it...get it done and ride.
04-16-12, 11:29 AM
As for the point about half-radial lacing wheels, Sheldon explains it in his wheelbuilding article. http://sheldonbrown.com/wheels/index.html
2x and 1x are used because with a large-diameter hub flange, 3x sometimes puts the spokes at a greater-than-optimum angle for transferring drive (or puts them in the way of the spoke holes in the flange)
04-16-12, 11:30 AM
According to Shimano, rear hub brake wheels should be built asymmetrically. ?
Asymmetric lacing usually means radial on one side and crossed on the other; I'd be surprised if Shimano said this.
Usually lacing is described as mirror-image, or symmetrical to define the relationship between the pulling vs pushing spokes and the inside vs outside heads.
Here's a good primer: http://pardo.net/bike/pic/howto-001/asymmetrical-lacing.html
04-16-12, 11:33 AM
Check out the bottom right corner of this Service Instruction for a disc freehub. Unless I'm entirely wrong, rear disc wheels are recommended to be laced asymmetrically. It's probably something that doesn't really make that much of a difference, like where you break a Shimano chain in order for maximum strength, but like that, if there is a reason the engineers recommend doing it that way, I would like to know what it is.
04-16-12, 12:13 PM
1. Cut those graphic squares out...
2. Align them upright on edge on a table...parallel to each other.
3. Have the graphics facing outwards.
What you'll see is that they want you to build the wheels such that the lacing is ALL INSIDE PULLING SPOKES.
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