Spokes:
When you consider how light a spoke is and the incredible job it must perform to ensure a reliably strong wheel, it becomes obvious just how important they are. And yet spokes are often not given enough thought when buying a complete bike or a set of wheels. The best quality spokes are of the highest priority in my custom wheel builds. Over the years, I have relied on a small number of top quality spoke manufacturers. In the 1970's I used Robergel spokes from France. They were of an outstanding quality but sadly, they are no longer available. In the 1980's I switched primarily to DT Swiss spokes and found them to be very consistent. Of late I am primarily working with Sapim spokes from Belgium and enjoy a diverse selection of models within their line, especially their CX Ray bladed spoke. Sapim have been making spokes for a century and have proven themselves extremely reliable with excellent overall quality control. Pillar Spokes from Taiwan, made from Swedish Sandvik T302 steel also have a few special models that I am presently testing.
Spoke nipples: If spokes don't get much thought, spoke nipples get even less, but they should definitely not be overlooked. It's the single lightest component on your bike but it performs an incredibly important task. I prefer using the best quality brass nipples for most of my builds due to their strength and reliability. A few companies like Sapim, DT Swiss and Alpina offer dual interfaces. A conventional 4 sided standard interface on one end, and a different shape interface on the other end of the nipple. This enables you to use various dedicated spoke wrenches to achieve high tension without doing any damage to say an aluminium colour anodised nipple. It also can be useful when building with bladed spokes. The ability to turn the nipple from behind the rim enables you to hold a bladed spoke with better ergonomics. Lastly, but highly important, is the strength gained at the nipple and spoke juncture because of the added material from the dual interface. The 5.5 mm HEX interface is my personal favourite. When weight savings is a prime consideration, aluminum nipples made from 7075 T6 alloy are a possibility for ultra light racing wheels, like those available from Alpina in Italy or Sapim from Belgium. But keep in mind, alloy nipples are prone to corrosion if exposed to salt water and may in some cases not last as long as brass nipples.
Bladed or "Aero" spokes: Is there a convincing reason for spending more money on bladed spokes? I would definitely say yes, but not for the reasons that some might think. When bladed spokes came into common use the thinking behind their invention was for a perceived aerodynamic advantage primarily for time trialists and other racing disciplines. Though bladed spokes are narrower they have a wider cross section. In one direction they do cut through the wind better, but if the wind is coming from the side they are actually catching more wind and their aerodynamic advantages quickly diminish. So why would I recommend a spoke that had some aero advantages in some circumstances and maybe none if the wind wasn't in your favour? In a single word it would be strength. A spoke like the Sapim CX-Ray has phenomenal strength in comparison to virtually any other spoke currently in production. It's almost as light as a titanium spoke but has greater strength. Sapim claims that their CX-Ray receives the best results in fatigue tests of any spoke on the market. The tensile strength of the middle section of that spoke is an incredible 1600 N/mm2! Another advantage of using this spoke is the amount of spoke surface where any two spokes cross. In a typically laced wheel pairs of spokes cross and support each other. The additional material in the widest section of the spoke adds support and actually stiffens the wheel when it's brought up to tension. In my opinion that is the strongest argument for their use. The added stiffness benefits wheels with lower spoke counts measurably.
Spoke count: These days most rim and hub manufacturers supply their products with the option of numerous spoke hole counts, commonly ranging from 16 to 36 holes depending on the end usage of the wheel. If we explore a bit of history on spoke count it shows that through the last few decades the trend has been "less is more". For many years prior to this the 36 hole wheel was an almost industry standard. Both racers and cycle tourists alike took advantage of its strength and reliability. Admittedly it was an engineering marvel, proving both light and incredibly strong. But as the quest for greater speed took priority, the racing community pushed the design envelope in search of greater gains, and this manifested itself in wheel designs utilising less spokes. One might ask, what happens to a wheel when less spokes are used and should I be considering wheels with low spoke counts? Briefly, when a wheel is built with a higher spoke count the overall tension is distributed far more evenly, and each individual spoke is responsible for less of the overall load. Conversely, in a low spoke count wheel each individual spoke is forced to carry a much heavier load, and as one reduces the spoke count there are less spokes to fine tune both roundness and side to side deflection. Also, should you break a spoke for any reason, the wheel would likely go very out of true, possibly rendering it unusable if frame and brake clearances were tight. Not all cyclists are aware of these inherent limitations when requesting the lower spoke counts. It's definitely food for thought. Personally, I recommend sticking with 28 hole wheels for off road applications like gravel riding and 24 holes for most road riders of average weight. Front wheels can take advantage of slightly lower spoke counts as the front wheel has no dish and doesn't support the majority of the riders weight. Time trialists and triathletes will want to consider the lightest options, especially when fractions of a second can determine the winner.