Check out
JVN's Design Calculator. It hasn't been updated with 2012 motor data but it is still one of the best resources for drive train calulations. You should be able to check what your top speed was on your robot from last year by putting in all the numbers.
Also here are the
updated motor specs for this year (as of 1/16/2012).
For what's it's worth we're gearing for around 10-11ftps this year.