Originally Posted by
Doohickie
butted spokes are actually more durable. Because the smaller gage section of the spoke is less stiff, it "gives" a little and avoids overstressing the elbow bend at the head (which is usually where spokes fail from fatigue), thus they last longer.
Well, I actually do have a lot of experience, and it has lead me to the opinion that a properly tensioned straight-gauge wheel is as durable and actually more reliable for commuting conditions.
I have seen many variations of this "flexibility" idea over the years and believe that it has become confused. It is not about flexibility, it's about stretching under tension. A flexing piece of steel will work harden and be more prone to breakage through metal fatigue. The advantage of butted spokes is not to be more flexible, but allow more tension (which results in a more stable wheel by lowering the probability of loosening nipples) as well as to save weight. The key to wheel durability is to reduce this flexibility. Straight gauge spokes that are tensioned properly will have no durability disadvantage. In demonstration, the straight gauge front wheel on my commuter was built by me almost 30 years ago and is as true and round as anyone but a dial indicator-wielding perfectionist would accept. I tweak it if it needs it whenever I replace the tires every few years. The back wheel of the same age has had a few more problems, but hey, isn't that the way things go!
The problem is that some rims will not withstand the tension required for straight gauge spokes. This is why butted spokes are used. They stretch (not to be confused with flex) more allowing more tension without overloading the rim. Under-tensioning is the culprit - because it allows flexing which in turn leads to metal fatigue and breakage. Under-tensioning also allows spokes to become looser, which then allows flexing, etc. I have helped others others many times with their wheel issues and have found it remarkable that most wheels are under-tensioned when built. I think straight-gauge spokes have gotten a bad rap just because they are easier to build and true without proper tension.
One observation that I have is that when I break a butted-spoke, the wheel reacts a little more than when I break a straight-gauge spoke. This is probably because of the higher tension. The last time I broke a spoke I didn't even notice it until a half mile later when it unweaved itself and started to bang around. I wrapped it around another spoke to stabilize it and rode it for another two weeks before I had a chance to replace it. Try that with a highly tensioned, low spoke count wheel.
-G