seshYou're at the trailhead.
Sesh is a downhill mountain biking app — see your friends live on the trail, replay your day lap by lap, and race the rider you were last week. It's free, with no ads and no selling of your location. Today it's in closed testing on Android; there's no iOS app yet.
Sesh is invite-only. Ask the rider who showed you this to invite you from the app — they type in your email and send you the link.
No invite yet? Get on the list.
Drop your email and it goes on a list a person reads by hand — there's no automatic reply. Or ask the rider who showed you this to invite you from the app.