I actually have seen that bike before. And those marks are from the sprocket bolt resting against the inside of the SPROCKET BOLT HOLE. the marks are from the threads of the bolt, clearly NOT a drill bit you tool. If it was drilled out, then tell me why the entire hole is not bare metal and you can see the black anodizing on the unmarked side of the hole from when they painted the sprocket, after the hole was made?