on a somewhat related note, are there opinions about running larger vs smaller chainrings/cogs in the same ratio? such as a 48/18=2.667=72 inches vs a 45/17=2.65= 71.5 inches. Roughly the same, but does the larger cog in the rear (in the first example) give you better torque or is it offset by the smaller chainring in the front in the second example?