Why should one choose double butted spokes over plain gauge spokes if you have the option?
This is a contentious issue as some people believe plain gauge spokes to be stronger than double butted spokes. The longevity of spokes has little to do with absolute strength, as even the lightest spokes have a breaking strain of over a ton.
Due to the thinner mid-section, double butted spokes such as those by DT Swiss are more elastic and able to “stretch” slightly and cushion the fluctuating spoke tensions as the rim encounters obstacles and hence deflects to a degree. Plain gauge spokes don’t have as much “give” and therefore will fatigue more quickly than butted spokes and will have a higher breakage rate over time. Think of how a paperclip breaks when you bend it back and forth. This is called metal fatigue.
It’s for this reason that I always recommend double butted spokes. Butted spokes are also a bit lighter than PG spokes – for some guys this is important 🙂
You have to be a lot more careful about windup in butted spokes. You have to detension each spoke more carefully when building by turning a bit extra and turning back. Otherwise they might re adjust themselves. I think 14g can carry a heavier load than DB.
Yes you do have to make sure that there’s no wind-up. I do destress the wheels very carefully during building with this in mind. DB spokes are more elastic, so even if they’re strictly not as strong as plain gauge, they last longer because they tend to suffer less from metal fatigue.
Plain gauge spokes have a breaking strain of around 1800-2000kg, where DB spokes breaking strain is around 1300-1600kg. Bear in mind that wheels are built with spokes tensioned to around 100-125kgf per spoke. Theres no way that you’ll get over 1000 kgf into a spoke while riding the bike, so the material strength is actually moot.
Thanks for the useful info.