Originally Posted by
RiddleOfSteel
Very interesting, all of this. I've built with double butted spokes (2.0-1.8-2.0 and 2.0-1.5-2.0) and the resulting wheelsets have been fine. Nothing to gush over other than the considerable weight savings over straight gauge spokes, IMO. I am in the middle of building a set with Ultegra 6500 hubs, polished H Plus Son TB14 rims, and DT Swiss Champion straight gauge spokes. 2,045g for the wheelset. Not light! Sure, the TB14s are a hair over 500g--no Open Pros that's for sure--but a lot closer to 200g could be shaved in switching to butted spokes alone.
I've built TB14s to both 7400 Dura-Ace hubs and Superbe Pro hubs, both times using the fancier butted spoke profiles (1.5 butting for the front and NDS rear, 1.8 butting for the DS rear). Both times the resulting ride was less than desirable over Seattle streets unless the tire size was 35mm or bigger. Given that (broken record here) straight gauge 36-spoke wheels on my Cannondale SR don't kill me, and neither does the 6400-to-Matrix-Iso-C-II wheel build (straight gauge again) on my OS Paramount, I am hopeful and certainly a somewhat confident that a straight gauge spoke setup on these TB14s will yield a more cohesive and pleasant reaction to street irregularities. So I'll take "less stiff" if it means everybody in the wheelset ecosystem gets along better. The wheelset will certainly dazzle with all it's anodized and polished pieces, which is a big reason I built it up.
Not to pick on you particularly, but your comment is what I see as a large part of the problem when it comes to wheel strength and wheel strength testing. Everyone concentrates on the rim as the place of strength which, in my opinion, is misplaced. I
don’t use (supposedly) strong rims and don’t see any real difference in wheel durability even though I’m a large, aggressive rider. I use Mavic XC717 rims and/or Velocity Aeroheats on my mountain bikes (559mm rims) which are 420 g rims. I don’t currently use Velocity A23 on my loaded touring bike but I would have no problem whatsoever trusting them to carry the load. Rims really don’t add much to the strength or durability of the wheel given the way in which the rim interacts with the spokes. Spokes do all the heavy lifting and get none of the credit.
Consider what “kills” a wheel. If you crack a rim due to spoke tension, the wheel isn’t “done”. It’s somewhat trivial to replace a rim if you have one with the same ERD. Reduce tension on the spokes and swap them over to the new rim. I’ve done it a number of times when I can find the same model rim or one with a similar enough ERD. But break a single spoke and the wheel is somewhat suspect. Break another spoke and the wheel is more than “somewhat” suspect. Break a third spoke and you should seriously consider rebuilding the wheel. Break more than 3 spokes and you are just wasting your time trying to keep up with the cascade of spoke failure that you are going to be dealing with shortly.
And if you just go by the posts here in the Bike Forums, rim failure is relatively uncommon. Spoke failure, on the other hand, is a far more common topic, especially in the touring and Clydesdale forums where the loads carried are higher and the stress on the wheels are greater.