Hard, Strong, & Tough: Choose Two?

I don't know enough materials science to be sure that this is one of these meme-y "choose two" situations, but I got the impression from a Popular Science story that if you're manufacturing a bike lock—or anything, for that matter—you can't contrive for it to be hard, strong, and tough. (At least not in the technical sense. For those of you who don't have the relevant definitions committed to memory, I've included them below, courtesy of "the industry leader in manufacturing training," Tooling U.) 

Technical Definitions (source)

compressive strength	a material's ability to resist a squeezing force
shear strength	a material's ability to resist forces that attempt to cause the internal structure of the material to slide against itself
tensile strength	a material's ability to resist forces that attempt to pull it apart
hardness	a material's ability to resist penetration, indentation, or scratching; hard materials tend to be very wear resistant
toughness	the measure of a material's ability to absorb mechanical forces before it breaks; impact toughness is a particular category of toughness
impact toughness	the amount of energy that a material can absorb from a sudden, sharp blow before it breaks or fractures

Popular Science only introduced the trio of macho adjectives hard, strong, and tough, though, as prelude to what PS writer Theodore Gray terms a "fatal flaw" of nearly all materials: They become less flexible when very cold.

Cooling a tough-looking (informal usage, that) lock to –13°F with compressed difluoroethane, for instance, leaves it vulnerable to attack by a hammer:

Don't think bike thieves employ to such tactics? I've been tracking down and reading interviews with reformed bike thieves, and my research indicates...well, I'll save that for another post.