I never understood the whole compact crank thing anyway. I always used a 42/52, 42/53 and occasionally a 39/53 and a 12-21 or 12-23/25 and never had too much trouble other than just not being a good climber.

it seem to me that all a compact does is make you spinn more as you have a 12-21 cassetter but your chainwheels are only 34/50? seems to me you would be spinn ing too much in the 24 16/17/18 gears and lacking top end on the 50 12/13/14

I think the 'leverage' part comes from grinding up 18 - 20 kilometer long 7%+ grade mountains you simple don't go as far on a one pedal stroke with a 34/50 21-23 as you would from the 39/53 21-23 for about the same effort.