Back in the old days of sprinting, everyone rode tiny gears and span like the clappers.  It's reported that Gary Neiwand rode 92" at the Sydney Olympics (old days? That's only 11 years ago!).  Rev rev rev, that's what the coaches of the time drummed into everyone who was sprinting.  But now, everyone's (the ones who are winning, anyway) pushing bigger gears.  MUCH bigger gears.  I've personally seen 10.1 flying 200's ridden on gears in excess of 106" by riders far from peaking for their best performances. I've seen the 50 metre splits for their efforts.  The guys recording the fastest times are not necessarly the ones with the quickest individual splits (although they can be!) - but their drop off in the last 50 metres is less.  This is partially a pacing strategy - watch a modern flying 200 and you'll see the jump happening later than you'd expect, and partially a result of using bigger gears.

Big gears mean more strength is required to get going in the first place, but also, less fatigue per meter ridden.  The flying 200, for example, is a speed-endurance event that has a maximal exertion time of around 14-16 seconds from the kick to the finish line.  According to a recent study[1] fatigue is brought about by the number of maximal contractions, not so much the speed of them.  If you can use less pedal strokes to cover a set distance by making the gear bigger, you will fatigue less PER METER and thus, probably have a greater average speed over the distance.  You need the torque to accelerate that big gear though, which is why riders like Shane Perkins, Chris Hoy and Anna Meares have huge legs and backsides and like to lift heavy things in the gym.  This applies to sprinters, not enduros.  Lance was superb at 120rpm spinning away up hills winning the Tour, but we're talking about short term sprint efforts where, literraly, every fraction of a second counts and we're not running aerobically.  Different animals ...

So, mash big gears with pride, but make sure you're strong enough to get them going in the first place!

I wrote more on this in the book :

http://upupup.aboc.com.au/the-book/07-racing/flying-200/choice-of-gears

[1] Fatigue during Maximal Sprint Cycling: Unique Role of Cumulative Contraction Cycles, ALEKSANDAR TOMAS, EMMA Z. ROSS, and JAMES C. MARTIN, MEDICINE & SCIENCE IN SPORTS & EXERCISE 2009