Sun Rhyno Lite rim warps when spoked - help!



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L. Smythe

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I'm building a Sun Rhyno lite rim with DT 14/15g spokes on a 32-hole Marzocchi QR20 front disc hub,
in a 3-cross pattern. I'm also using a Park tensiometer.

When I put the rim by itself on a flat glass table or a trued wheel, it looks flat. But when I put
the hub and spokes in and start tensioning the spokes, the rim weld area gets a lateral bump in it,
so much so that I need to tension the closest spoke to it by about 50% more than the other spokes on
the same side, and the two spokes flanking it on the other side of the hub need to be tensioned to
about 50% less than the other spokes on the same side. I also have trouble truing the rim (maybe
because of this) even when I slowly creep up on the tensioning. WTF??? Can there be flaws in the rim
which aren't visible when the rim has no spokes in it? I've just about given up on this rim, any
suggestions as to what can be happening here?
 
what you're experiencing is normal. the joint is not as flexible as the rest of the rim because it
has either been welded or has an insert. it's common, as you say, to tension spokes at the join
higher than the rest.

when using the tensiometer, you will likely /never/ have exactly even tension. readings need to be
averaged over a number of spokes. different rims have different degrees of this issue, and some are
better than others; just get it as even as you can.

finally, you may even out some of the extremes if you look at tensioning groups of spokes rather
than individuals. higher tension in one spoke may make a wheel spin true, initially, but it will
quickly go out of true in use. a more even tension in a group can achieve the same result and be
more reliable in service.

L. Smythe wrote:
> I'm building a Sun Rhyno lite rim with DT 14/15g spokes on a 32-hole Marzocchi QR20 front disc
> hub, in a 3-cross pattern. I'm also using a Park tensiometer.
>
> When I put the rim by itself on a flat glass table or a trued wheel, it looks flat. But when I put
> the hub and spokes in and start tensioning the spokes, the rim weld area gets a lateral bump in
> it, so much so that I need to tension the closest spoke to it by about 50% more than the other
> spokes on the same side, and the two spokes flanking it on the other side of the hub need to be
> tensioned to about 50% less than the other spokes on the same side. I also have trouble truing the
> rim (maybe because of this) even when I slowly creep up on the tensioning. WTF??? Can there be
> flaws in the rim which aren't visible when the rim has no spokes in it? I've just about given up
> on this rim, any suggestions as to what can be happening here?
 
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