Strength and stiffness are not the same. Stiffness is the extent of elastic deformation for a given force. Strength is the force required for permanent deformation, which, for spokes in a given configuration, depends on the material and how it was worked. Stiffness only depends on the material and cross-sectional area. So, for example, butting a straight-gauge spoke to reduce the middle diameter will reduce stiffness and (potentially) increase strength.
Tension doesn't affect stiffness because it doesn't change the Young's Modulus of the material. Whether a material starts in tension or not, it'll stretch the same distance in response to a force (within its zone of elastic deformation). More tension does increase load capacity and reduce spoke fatigue, however.
Since we're talking about ride quality: from a (simplified) physics perspective, a bike is just a spring series. Tires, rims, spokes, suspension, frame, post, and saddle all have effective spring rates. _The higher the spring rate of one component relative to the others, the less relative contribution it has to ride quality._ If you apply a force to something stiff connected to something flexible, the flexible thing will yield a lot and the stiff thing won't yield much at all.
In this system, spokes are \*really\* stiff. So are carbon rims. Frames and posts, a little less. Tires, saddles, and suspension are much, much less stiff, often an order of magnitude or more. As a result, these latter three absolutely dominate ride quality perception. Spoke counts, lacing pattern, materials, and type have a substantial effect on lateral stiffness, but on the vertical? The rest of the system obscures their contribution.
Oct. 12, 2018, 3:23 p.m. - Alex D
Strength and stiffness are not the same. Stiffness is the extent of elastic deformation for a given force. Strength is the force required for permanent deformation, which, for spokes in a given configuration, depends on the material and how it was worked. Stiffness only depends on the material and cross-sectional area. So, for example, butting a straight-gauge spoke to reduce the middle diameter will reduce stiffness and (potentially) increase strength. Tension doesn't affect stiffness because it doesn't change the Young's Modulus of the material. Whether a material starts in tension or not, it'll stretch the same distance in response to a force (within its zone of elastic deformation). More tension does increase load capacity and reduce spoke fatigue, however. Since we're talking about ride quality: from a (simplified) physics perspective, a bike is just a spring series. Tires, rims, spokes, suspension, frame, post, and saddle all have effective spring rates. _The higher the spring rate of one component relative to the others, the less relative contribution it has to ride quality._ If you apply a force to something stiff connected to something flexible, the flexible thing will yield a lot and the stiff thing won't yield much at all. In this system, spokes are \*really\* stiff. So are carbon rims. Frames and posts, a little less. Tires, saddles, and suspension are much, much less stiff, often an order of magnitude or more. As a result, these latter three absolutely dominate ride quality perception. Spoke counts, lacing pattern, materials, and type have a substantial effect on lateral stiffness, but on the vertical? The rest of the system obscures their contribution.