KOM Attacker is an android app that provides auditory prompts in real time to help you pace your attack on specific segments.
From the site:
Get out there and take a KOM helped by KomAttacker!
1. Login with your Strava® credentials
2. Select the segment
Set the target segment, selecting it from a map, from your Strava® starred segments, or for a bit of fun, from a KOM owned by your Strava® friends!
Start the attack, put on your earphones, and go into battle! A voice will tell you when you start the segment, and the gap in real time,as if you were a pro receiving commentary from a Sports Director during a time trial.
If you have your phone on the handlebar, you can also see the gap at a glance.
At the end of the climb you'll either be a Winner or a Loser, and the attempt will be stored in your phone, so you can see the history of all your attacks at any time.
Remember to start the Strava® app as well to record your activity. Alternatively, KomAttacker stores a .gpx file that can be uploaded to Strava®.
JUMP ON YOUR BIKE AND PUT THE HAMMER DOWN!