Folks, I need some advise.

I got this Garmin Edge 800 and the SpeedTrap (ANT+) sensor.

Do I still need to have the SpeedTrap on Trek 2.1 or I just rely on the Garmin GPS to determine the speed.
Or am I mixing things up?

Whats the benefit of having the SpeedTrap?

Here ya go: https://forums.roadbikereview.com/com...or-299706.html

Thanks for the info!! That clears out my confusion.