Does the 705 only use the GPS for it's speedometer? If not, is the 705 compatible with the Trek Speedtrap sensor?

If it's only obtained via GPS, have you found it to be as accurate as a bike computer with fork/wheel sensor?

No. If you have the Garmin Speed/Cadence sensor (GSC10) it will use that before the GPS data for the speedometer. The GPS is used to ensure that the data from the sensor is correct. All of the GPS data is save in the ride log file and can be used by many different software packages for post ride analysis.


Dont know. Is the Trek Ant+ compatable?


I have always used it with the sensor on my road bike since I like the cadence data too. I have used it on my Mtn bike some where I have no sensor and it worked just fine.