Gear Ratios

[silver_vti]

i was taking a look at a net mph calculator using gear ratios. can anybody tell me why is it that larger gear ratios make lower top mph per gear?
tks

 

[posol]

think of a 10-speed bike. the BIGGER gear in back, was also the easiest to pedal, but the top speed was low. same conecpt. and where you pedal, thats the final drive sprocket.