You"re on the right lines, in that it is the flying start that makes the difference. Given that he was never able to break 10 seconds for the 100m, it is surprising that Johnson"s time for the last 100m of his 200m WR at 9.20 was actually faster than Bolt"s equivalent 9.32, but he was slower over the first 100m. However these are way off the times achieved in relays, where 9 seconds has been broken more than twenty times, most notably by Bailey, Greene & Burrell and four times by Lewis. Carl Lewis still held the two fastest automatically-recorded times, 8.85 & 8.86, right until 2007 when Powell did 8.84.
However, none of these came close to Bob Hayes, who won the 1964 Olympic 100m by a mile, equalling the WR 10.0 despite having the inside lane of a cinders track chewed up by the 10,000m. In the semis, he was the first to break 10 seconds, clocking 9.91, but the time was disallowed due to wind-assistance. He then came from way behind to win the relay almost single-handedly, running the anchor leg in 8.50 despite old technology track, spikes, clothing, training, diet, etc, etc and the disadvantage of having to run in black-&-white. Just to make it a real Alf Tupper moment, he forgot one of his spikes and had to borrow a left one. For some reason I don"t understand, manually-timed 100m have 0.24 added to compare with automatically-recorded. I understand timers" reaction times being added to gun starts, but not to relay splits. Anyway, Hayes" converted time is 8.74. No doubt he was one of the greatest athletes ever. He is the only man to win a gold medal and a Super Bowl and last week became only the second gold-medallist to enter the NFL Hall of Fame.
In the 08 Olympics, Bolt ran 8.98 and Powell 8.70, finally "breaking" Hayes" time. Bolt almost equalled that in his 150m WR this year, covering the final 100m in 8.72. Gay has also broken 9 seconds. For me though, Bob Hayes ran the fastest 100m ever. Here it is:
http://www.youtube.com/watch?v=kPDfT0ucUfc&feature=related
