Race pace mode is an advanced version of the 'Run To Pace' mode and comes as part of the Avanti package.
In this mode you simulate an actual race. You set your race distance and goal time and the pacer automatically configures itself to achieve that, all you have to do is remain level with the pacer to nail that race.
You can even setup an optional 'Sprint Finish' for those that like to blast to the finish line.
To set this up first go the workout section and press the plus button create a new workout.
Then choose 'Race Pace Mode'
Now on this next screen enter your desired distance (this will be km or miles dependent on how you have configured the app) and your goal time.
Next you can choose if you want a 'Sprint Finish'.
Finally you hit 'Save Changes' this is all illustrated below.