Electronics, Lighting, & Gadgets - Garmin Edge use speed/cadence sensor for speed or GPS?

I have been using a garmin colorado 450 using a garmin speed/cadence sensor to determine if I wanted a map enabled bicycle computer. I have decided I don't since the map display doesn't help me navigate while riding...

That said I am thinking of purchasing a Garmin Edge 500 bicycle computer to record riding tracks, speed, cadence, and heart rate statistics for my daily ride. I read the manual but it isn't clear what is used for the source of the recorded stats in the case of speed which could be coming from either the speed/cadence sensor (which seems optional) or the internal GPS.

Does someone know the answer (Garmin support leaves a lot to be desired)?

It uses the speed/cadence sensor when its available, better accuracy than the GPS.

I have a 305 and it seems to use the GPS for speed calculation by default and only uses the wheel magnet and sensor if the gps is not getting a good signal. I wish we could choose which we wanted it to use, but I've looked and it doesn't seem to give us the option. You can turn off the gps function and then of course it will calculate speed and distance by the sensor only, but I like having the gps data to import after the ride so I have to leave the gps on.

I have a 305 and it seems to use the GPS for speed calculation by default and only uses the wheel magnet and sensor if the gps is not getting a good signal. I wish we could choose which we wanted it to use, but I've looked and it doesn't seem to give us the option. You can turn off the gps function and then of course it will calculate speed and distance by the sensor only, but I like having the gps data to import after the ride so I have to leave the gps on.

Same here - I think that quirk is peculiar to the 305 as opposed to the 705 or 500.

According to Garmin, the Speed Sensor is the primary source if the Edge detects it. That said, have a look over in the Garmin Forums - there may be a glitch in the latest firmware that makes it perform the opposite.

For example, there's a guy who stores his bike in an underground parking garage. When he starts his ride from inside that garage, his 500 will measure speed, but it won't measure distance until he's outside and gets a signal. But if he turns the GPS off in the menu, he gets proper speed and distance.

I have the 500 as well with the speed sensor. I have yet to test this theory - but so far, the unit has worked flawlessly. I get really good coverage in my area. The first time I turned on the 500 in my basement, I got full reception in under 10 seconds.

Thanks guys, I guess I'll pick one up in a few weeks.