Originally Posted by
FBinNY
It's never too late to add a chainstay protector of CF frames. So far you've only seen cosmetic damage, but that can change.
FWIW - chainstay protectors fail to protect the most critical place, which is right by the chainring. Chain suck or something similar can jam the chain up against the stay with the gap being too narrow to let it pass. This can cause serious local gouging, which a simple plastic film cannot prevent. It's a pet peeve, but IMO a ballistic plate, ie. shaped stainless steel, should be bonded to chainstays at this very critical location, to ensure the chain cannot cut into the stay.
I agree, with one suggestion: So steels have a lot of toughness, so can distort a lot without puncturing. However, that distortion could still damage the chainstay underneath. I think what would be desired is stiffness, to distribute an impact force over a much larger area. Accordingly, I would recommend high-strength aluminum, 3X the thickness for the same weight, would be good armor. Stiffness is a function of the cube of the thickness, for given material properties. Aluminum is only 1/3 as stiff as steel, but 3X thickness cubed, is 27X, divide that by 3 for less stiff material, and you still get 9X as stiff.
I worked for a time in military vehicles, including armor. Sometimes you need ultimate strength, sometimes you need stiffness, sometimes you need hardness. Often combinations of the above. But it often takes different approaches, based on what is immediately behind the armor.