Originally Posted by
FBinNY
The claim that an aluminum fork will give a harsh ride is absolute nonsense. The ride properties of any fork, of any material will be determined by the wall thickness, taper, curve and mechanical properties of the material.
Steel has roughly three times the stiffness, three times the strength, and three times the weight of typical aluminium alloys used in bicycle frames, but there is another factor which makes things complicated - the part is a tube.
As such, the stiffness of the PART depends on the distribution of the metal as well as what it is. An aluminium part needs more metal to be as strong; that metal has to go somewhere, and if it increases the section modulus sufficiently that part will be stiffer than the same strength part made of steel. The outer diameter of bicycle fork tubes is not (usually) constrained, hence stiffer forks.
But none of it matters anyway - tyre pressures and compliance dwarf any fork differences (speaking for a friend).