This app was mentioned in 7 comments, with an average of 7.00 upvotes
There is a RoadID app that I use whenever I'm planning to ride more than 2 hours, or am riding somewhere unfamiliar. My wife appreciates it, and if I feel like extending my ride I can.
Google play link. https://play.google.com/store/apps/details?id=com.roadid.ecrumb.app
tl;dr we're making a crash sensor that texts people for you so you don't bleed out on the side of the road
LOL have fun with the false positives. Oh did I put my helmet down too hard and alert everyone?
What you are looking to solve is already solved better by free tracking apps. RoadId:
Appstore: https://itunes.apple.com/us/app/road-id/id569352341?mt=8
Android: https://play.google.com/store/apps/details?id=com.roadid.ecrumb.app&hl=en
Allow anyone, for free, to track a rider and that rider can setup alerts based on stopped time. This is a MUCH better approach than some half-assed who knows what sensor ... and it is free. No false positives, no MBA student created nonsense; it just works. FOR FREE
A couple free alternatives, in addition to others mentioned, for folks who aren't aware:
Strava has a beacon function but that only works if you're a premium subscriber. I use an Android app called Road ID that let's people know I'm biking, then if I stop in the trail for more than 5 minutes without telling the app, an alarm goes off for 60 seconds and then sends messages to my set contacts letting them know my exact location and to contact emergency services. https://play.google.com/store/apps/details?id=com.roadid.ecrumb.app&hl=en
The road id app is fairly savage for this kind of thing , presuming you have mobile data available to you. Its more aimed at alerting a friend that you havent moved in the case of an accident , but might help ?
https://play.google.com/store/apps/details?id=com.roadid.ecrumb.app