Garmin has just introduced the Edge 810 gps/cycle computer. A review is here.

http://www.cyclingnews.com/reviews/g...st-ride-review

I haven't read the whole thing carefully -- my Edge 500 is less than a year old so I have no plans to replace it at this time. But this jumped out at me, since it looks like a useful safety feature --

"A new LiveTrack feature shares your ride progress in almost real time. Data transfers at regular intervals from the Edge unit to a connected smartphone, which then relays it to selected recipients – or to all of your Facebook friends or Twitter followers.

This should be a boon for solo riders who would like to reassure loved ones they're safe..."

If this unit had been available a year ago, that feature would have made me strongly consider spending the extra money for an 810 instead of a 500 or 510.