I am old enough to remember when Phil Wood came out with 48 spoke hubs for tandems. They were a godsend. I was always breaking spokes on my tandem with 36 or 40 spokes. The problem was, back in the day Super Champion rims were the best, but they were a bit soft and shallow in depth, so they flexed more than was desirable. That flex caused spokes to break. 48 spokes controlled the situation. Now with deeper, stiffer rims, that is no longer necessary. Rims like the Velocity Dyad are stiff enough for me even at my weight (I am a Clyde), but I still prefer to go with 40 spokes, even on a single bike.