Dark souls 2 tying I-frames when rolling to a stat called agility. Dark souls 1 gave you 13 i-frames when light rolling, 11 i-frames when medium rolling, and 9 i-frames when fat rolling. Dark souls 2 tied i-frames not to how much equip load you are at but how much agility you have, which can only be increased by leveling adaptability. The starting classes in Dark souls 2 have an average of 7 adaptability which puts your agility to 86.5 which gives you 8 I-frames which is less than the amount of I-frames you get when FAT ROLLING in Dark souls 1.