Originally Posted by
LeeG
I said "is also a function of" not "defined by". Wheel longevity is how long the wheel functions "as a wheel". When spokes break, it's no longer functioning, when the rim wears down to compromise strength it's near failure, when multiple blips occur from bottomed tires (full inflation isn't always optimum and some impacts damage tire sidewalls and rim without taking entire wheel out of true) repairs don't always bring the braking surface back to 100%.
A wheel can function "as a wheel" far longer than an aluminum rim can. The very nature of a rim brake equipped wheel is that some of the rim material gets removed each time you use the brakes. But once the rim sidewalls reach a point where they can be used for braking anymore, the rim can be replaced and the wheel, i.e. the important bits like the spoke and hub, can continue to function. You are correct that breaking too many spokes leads to wheel in which the systemic problem must be addressed which, usually, means that the wheel has reached its useful life. But having to replace the rim, doesn't mean that the wheel is done for.
As for blips, there is absolutely no reason to run a tire at such a low pressure that it can't provide impact resistance, especially when carrying a touring load. In fact, running it too low will lead to the more immediate problem of pinch flats. Even when running low pressure like in a mountain bike, the tire is meant to protect the rim by having a larger volume.
Originally Posted by
LeeG
Sure you can consume rims, build up a light rim with plenty of spokes and you can have no spokes break but cracking can occur at nipples.
Again, not an issue where the wheel has failed but a replaceable part of the wheel has failed. And, if you build the wheel properly, cracking won't be an issue. Cracking isn't really caused by too much tension but by too little and the movement of the spokes in the hub...another problem that is fixed by the larger diameter head of the spokes I mentioned.
Originally Posted by
LeeG
I wouldn't want to rebuild a wheel using spokes where adjacent spokes have broken.
And why not? Because the spokes do all the work and a dead wheel is defined by the number of spokes that have failed due to fatigue.
Originally Posted by
LeeG
I am guessing Steveage wheel had simply gone through enough damage where the rim is bent and spoke tension can't get it back to true so some spokes are simply cycling through too large of a range of tension. A heavier tougher rim will be less likely to get whacked out sideways and less likely to need uneven spoke tension to get it back to true.
If the rim "wears out faster" then what the op is concerned about , longevity and cost, it doesn't meet his goal by replacing his old wheel with one that will need more frequent replacement.
I don't see anywhere that stevage says that the rim was bent. He said "I just broke a couple of spokes on that kind of 5 day tour last week (caused by rim wearing out, I think)" which says to me that he replaced the wheel because of broken spokes which he misdiagnosed as a worn out rim. I suspect that the braking track on the old wheel isn't actually worn out, however.
And a stronger spoke would resist damage that might make the wheel go out of true far better than a heavy rim would. The way you true wheels isn't by bending the rim into a straight shape but by adjusting the tension forces on the rim
with the spokes to straighten the wheel. The actual rim is rather pliable and easily bent...even steel rims aren't that strong as just a rim.