thing about not getting a bike thru your friendly bike shop is you are left to your own devises
and emailing the warehouse they ship out of.
if you have the gear ratios that those 3 or 8 speeds represent , you can answer your own question.

there are online math calculators for bikes like this one :
http://sheldonbrown.com/gears/internal.html
input the size of the chain ring , and hub cog and wheel size .
the relative sizes of the external chain drive determine where the range of gears are,
and by changing the chain drive you change where the gear ratios are.