It is the first light beam after the tree, 60' from the starting line. The light is actually on the outside of the lanes, and the box in the middle of the track are just reflectors, so if they are hit by a competitor, they are quickly replaceable.
cool. according to a video a friend took, it appears that i am shifting before i reach the 60' mark. i wonder how much time i am loosing for my granny shifting.