But. Does it really? REALLY? Will anyone notice the extra width and stiffness offered by 3mm.
3mm.
If a reviewer can genuinely feel the difference, I’ll eat one of my (cycling) helmets.
can be interpreted in different ways. if they mean specifically the chainstay, then increasing the available space (with suitable clearances) between tyre and chainring could be significant, say from 10mm to 13mm.
As the stiffness of a thin walled tube is proportional to the cube of its diameter, going from 10 to 13mm, all else being equal, has mre than doubled its stiffness.
But what this does to the overall rear end stiffness, ie what a rider can feel, is anyones guess and determined by the entire system, not just a stiffer chainstay.