I'm impressed with the "stock" fitness app. I used the "outdoor cycle" option on my watch along with my Garmin GPS bike computer to compare. The results were identical! The disadvantages (to using Apple's app alone) is that with the Garmin bike computer, it's in my face the whole time. With the watch I need to turn my wrist for readings. Also Apple's App doesn't "map" my rides. So, I've decided to use the watch, by itself, on short rides (under 20 miles). Then for longer rides (I usually ride 20 - 45 miles) I'll either use both or just the Garmin. I've also used Apple's Workout App for indoor cycling too. I'll be trying out the other options as well. Oh, I used (and ditched) Strava, on my watch, for cycling . It was a total disaster.