i have a garmin 735xt and I love it it records my rides and runs and uploads to strava with ease I don't need sat nav is there any need for me to get a garmin cycle computer I can buy the sensors and connect them to garmin watch so what's the real need for a computer?
With your watch, you can connect it up to Ant+ speed and cadence sensors, so the only thing you would be missing is mapping. A Edge cycle computer should last an easy 9-10 hours, can your watch? Obviously if you mount your watch on the handle bars you lose the Heart Rate tracking, but I find that a bit iffy on a bike anyway.