Just bought the Kilo S3X from bikesdirect, I like it but the gear ratio (48:16) is way too low considering the gears only shift down from there. I believe the three gears are direct, 1:0.75 and 1:0.625. I have two questions:

1.) Can you put a 12 tooth cog on it? I'm not sure it will fit.
2.) Will a 12 tooth, on the middle gear (1:0.75) be roughly equivalent to how it is now on the direct gear, because 12 is 75% of 16?