dunno, not really impressed when youre in a custom fancy tech'd out "bike". who knows how much extra hes getting from the design, gears etc.
Well, specialized equipment is what the world of speed records is all about. There are also records for other types of bicycle categories and this is just one more of them. It's a very specialized and exacting science where many factors have to come together perfectly in order to challenge the record. The old record stood for 6 years...so it's not a small achievement. It's not really a factor of extra's, it has more to do with getting things to minimums such as parasitic drag.
The gears are only there so that he can be at his most efficient cadence when passing through the speed trap but don't by themselves do anything to improve speed. If that gear ratio was on a typical road racing bike is would serve no additional advantage. There is hardly anyone who can "spin out" the average racing bike with the standard 53 tooth front ring and a 11 tooth rear cog, on level ground and still winds. Some professional sprinters can do it which places the rider and machine right around 42-44 mph. Air resistance is 95% of the game with the remaining drag being rolling and mechanical.
Since it takes substantially more power to go just fractionally faster it's not so much an issue of the riders getting stronger but the technology bar advancing, with the largest gains in the area of aerodynamics.