I don't use strava, I use Map My Ride so I cannot comment on Strava but I can comment on using a phone for GPS. The primary issue I have had is battery life. I have a Nexus 5. I put it in a pouch so it can make it fine through a 50 mile or so ride from a full charge. I have also bought a battery backup but haven't used it yet. We ride in the open country so I have never had much of a problem losing the GPS signal. I am happy enough with using the phone I see no need to buy a purpose madebike GPS system.