Originally Posted by nashvillebill

Fortunately, I am a mechanical engineer, so I can address this. The deep V-shape would indeed be stronger than a conventional flatter rim, if the material thickness is the same. However, this would add a lot to the weight of the rim (more material in the V shape versus the flat rim if the extruded aluminum was the same thickness). The extra weight is counterproductive though: it's not only increased the weight of the rim, but that extra weight is on the perimeter of the rim, which adds to the rotational inertia of the wheel. So manufacturers evidently have decreased the material thickness, which means that the overall strength of the rim could be same--IF we don't factor in the point load of the individual spokes, or increase the distance between them. Each spoke puts a high stress on the rim right at the spoke hole. Thinner material means the spoke can pull through the rim easier, which is exactly what happened on the Campy rim on that bike I bought. The spokes began to pull through and the rim developed longitudinal stress cracks propagating lengthwise from each spoke hole. Having fewer spokes compounds this problem since each spoke sees more tension (than a comparable wheel with more spokes)--higher tension on each spoke plus thinner material. Plus, having fewer spokes increases the distance between each spoke. For any shape that must withstand forces, increasing the distance between the supports is increasing what we call the span. Fewer spokes means a longer span; having a longer span increases the deflection and increases the bending stresses for that span.

So yes, the rim is absorbing more of the "pressure"--but that is exactly what we don't need! The lifespan of the wheel can be reduced if we have fewer spokes because a) each spoke is putting more point load on the rim and b) the distance between spokes is increased which puts more stress in the rim. Yes we've saved a few grams by reducing the number of spokes and making them a few millimeters shorter, but we've had to change the shape of the rim to a deeper profile and decrease the thickness of the rim material to avoid the weight penalty of the deeper profile.

Imagine if you were getting on an airplane and the pilot came on the intercom to announce "hey good news folks, our wings are now 10% flimsier"....