So I do not feel the urge to blow through stop signs and red lights I use this feature with my Garmin:
Using Auto Pause
You can use the Auto Pause feature to pause the timer automatically when you stop moving or when your speed drops below a specified value. This feature is helpful if your ride includes stop lights or other places where you need to slow down or stop.
With my Garmin 520... I use select custom speed... and set it to 6 MPH. Anything below 6... The Garmin will pause. When the light turns Green... It is now a sprint to get back up to your pace. You do it this way:
1 Select Menu > Settings > Activity Profiles. 2 Select a profile.
3 Select Auto Features > Auto Pause.
4 If necessary, select Auto Pause Mode.
5 Select an option:
• Select When Stopped to pause the timer automatically
when you stop moving.
• Select Custom Speed to pause the timer automatically when your speed drops below a specified value.