Originally Posted by
cyccommute
(Sigh. Do I really want to go down this road? I don't want to but I guess I'll have to. Here goes...)
Even spoke tension? Yes. Correct spoke tension? What is that? Strong rims? What does that have to do with wheel strength?
Yes, by all means the spoke tension should be even and consistent. But show me a chart that tells a wheel builder what the "correct" spoke tension is. The variables are too many...what rim, how many spokes, what hubs, what spoke gauge, what spoke nipples, rider weight, rider use, etc?...for any rim manufacturer to give you a "correct" spoke tension. Even the tensions that they suggest are across an extremely broad range and I would take as more of a CYA on their part than a real number. The real number may exist but I really doubt it. I've been building wheels for 40 years and I have yet to find that elusive chart.
As for the rim, first, you can't tell by looking that the rim is strong or weak. That depends on the thickness of the metal and the number of spokes the rim is supposed to be laced to. The rim doesn't do much in terms of resisting the forces that are placed on a wheel because the metal used...aluminum...is soft and small changes in the configuration won't make that much difference. Deep rims might resist upward deflection slightly more than a shallow rim but most of the deep rims are also narrow rims which means they don't resist sideways deflections as well. Wide rims might resist sideways deflections but they don't do much to resist upward deflection. Basically, any rim out there is probably adequate for the (fairly easy) job that rims have to handle.
The real work done to make a wheel strong is done by the most overlooked part of the wheel...the spokes! Spokes do all the work to keep the rim from bending side-to-side. Spokes do all the work of spreading around the load as the rim is loaded, deflected upward detensioning the spokes and then picking up the tension as the rim is unloaded. And the spokes do all of the work of driving the wheel forward or stopping the wheel as the hub goes around and pulls the spokes in the respective direction. Rims get all the glory but spokes do all the work.
You were right to begin with: you shouldn't have.
Correct spoke tension is near the max specified by the rim manufacturer, duh. Any decent bike shop will know what is correct for that rim. No great esoteric knowledge required, just a little curiosity. Gauge makes no difference. Number of spokes makes no difference. Rider weight makes no difference. One uses somewhere near the max DS tension specified for that rim in back, and about 85% of that up front. Basically, you want to use about as much tension as the spoke bed is designed to take. The manufacturer can quote you that. There are no "charts," unnecessary, which is why you've never seen one. There's no greater tension than max and no reason to use less than about 10 lbs. off max. You're making it way more complicated than it is, just to make it seem like it takes an expert. It does not, just someone who can read.
If you knew statics, you'd know that the changes in spoke tension and thus spoke longevity are dependent on rim stiffness. If it were a perfect box section, rim stiffness would go up by the 4th power of its depth, but in reality is somewhat less as the top of the section has less material than the bottom. In any case, that's not "slightly more" stiff. One can tell just by looking that these are relatively deep rims and the width of the deep section will make them extremely stiff.
We run CX-Ray spokes on our tandem, 36H rims, could be fewer, all up 335-400 lbs. Never broke a spoke. Cobbles, potholes at speed, etc., no problem. Some of that's from the 28mm deep rims and some because these are thin, fatigue resistant spokes.