08 Jamaica Trials - Men’s100m Finals: http://www.youtube.com/watch?v=Q-X53YulscE
I thought bolt shutdown was more obvious than powell. Judging from the arms of bolt i’d say he shut down at 70m, floating in to that 9.85 w-0.1.
With powell it seemed to be not as obvious but i’d say he shut down at about 70m as well(tempo type arm swing-rate and range), floating in to his 9.97 w-0.1.