Okay, so I see part of the problem here. "Pulling up" increases delivery of power to the drive train, because more muscles are at work. However, perhaps you are saying that the driving force is still being applied on the downstroke, and all that the pulling up is doing is lessening the deadweight on the upward bound pedal. However, even if that is always true (which is dubious) you are still delivering more power to the bike, and going faster (for the moment, until you get tired or acidotic).