Originally Posted by
Kontact
I don't know if the bolded actually makes any sense or are just words you're putting together.
It is also an assumption on your part that a spring rate has anything to do with "stiffness". And you aren't defining what sort of stiffness. Stiffness is a word generally applied to lateral bending, not tensile strength. Are you talking about the spoke or the wheel? Spokes don't benefit from stiffness - they are hinged top and bottom.
But tension is tension. The amount of force to put a thin spoke to 100 kgf is identical to the amount to tension a thick spoke to 100 kgf.
Every part of a structure has a resistance to deformation, whether it is in bending, in shear, in compression, in torsion or in tension. Once the part has it's dimensions and material defined, it can be said to have a spring rate along whatever critical direction that the expected loading will be applied.
In the case of spokes, obviously this will be tension force along the length of the spoke, and the stiffness or spring rate of the spoke will be proportional to the cross-sectional area of the spoke (and inversely proportional to the spoke's length).
Any vertical or lateral force applied to the rim of a built wheel will cause a change in the individual spoke's tensions that will alter their lengths and allow the rim to move relative to the hub. This is wheel flex, which can never be eliminated but which is reduced as the spokes become thicker (or more plentiful) and thus more resistant to changes in length.
Stiffer rims could be said to accomplish the same effect by spreading the localized loading near the contact patch out over a larger arc along the rim, and thus over a larger number of spokes, which in total represents a larger net cross-sectional area of spokes within the (larger) peak deflection zone.