1- convert a beater - cheaper - so to find out if you like it
2- buy some cogs - dura ace will work - from 14t 15t 16T flavors so to have options

start with the 16T for a whole week, then move up one at a time

if needed, go down on tooth count, or up, depending on how they feel for you or measure in your bike computer.

I go with 88 gear inches, but I do not cyclocommute every day.