I felt the same way originally about pushing in a higher gear vs what felt like slacking. But then the great Sheldon Brown's Pinache eagle swooped down on my handlebars, lowered my gear, pecked my damn wrist, and reminded me otherwise that it is not as efficient:
http://sheldonbrown.com/gears.html.
I wanted to post that today marked the 1 year anniversary of me biking to work (+public transportation). Some stats:
AVERAGE ROUND TRIP COST: $6.72
TOTAL COST: $772.52 (including bike purchase, parts, fares. carpooling the vast majority of balance)
MILES BIKED: 1770
CAR MILES SAVED: 9,177.0 (realize that moving would lower this nearly 100%..but a potential work from home scenario seems like a more nobel goal right now than moving 2 kids from their classes and family from home. Exercise in progress..)
CAR COSTS SAVED: $2,753.10 (@ .30/mi est)
One more thought before I sign off - I suggest you check out that Jacob podcast from Tues. if have not already. Good night!