I don't know. I locked a $1,500 105 groupset cross bike to the campus bike racks every day for three years of undergrad and three years of grad school and it never got stolen. I may have just been lucky, but that was quite a streak of luck if so. I locked the front wheel and frame with a Kryptonite U-lock and the rear wheel, front wheel, and frame with a Kryptonite chain and only did so during class hours and in busy areas. It never spent the night on a rack, as I lived off campus; I'm sure it would have been taken if I left it out overnight several times.

It was also neon green, so maybe its conspicuousness deterred thieves?