JAM Trail is a full-screen data field for trail running on the Garmin fenix 8 (43/47/51 mm AMOLED). It draws the elevation profile around your position at one fixed scale everywhere on the course, so the slope you see on the watch matches the slope you feel underfoot. Why: standard climb graphs (like ClimbPro) stretch every climb to fill the screen, so a gentle 5% hill and a brutal 25% wall look almost identical. JAM Trail never rescales a single climb. Every segment uses the same vertical exaggeration, so a steeper line always means a steeper trail. WHAT YOU SEE Elevation profile around your position, with your position marked. Choose a fixed window (500 m to 10 km) or fit the whole current climb or descent to the screen. Current grade in percent as a large, colour-coded number, averaged over 100 m (200 or 400 m also available). Grade colours in three bands (0-10%, 10-20%, 20%+), separate colour families for uphill and downhill. Automatic climb / descent / flat mode. On a climb or descent: average grade, steepest grade still ahead, remaining ascent/descent, and distance left. On flat ground: distance to the next climb or descent and how much it gains or loses. A marker where the current climb or descent ends, or the next one begins. Off-course warning with distance from the route. Large text throughout: nothing on screen is smaller than the watch's own menu text. HOW IT WORKS Convert a GPX course into a compact file and publish it to a web address (a converter and hosting setup are part of the open project). Open a trail-running activity at home with your phone nearby. The data field downloads the course through Garmin Connect and stores it on the watch, so it works with no phone connection once you're running. Your position is determined, in order of preference, from Garmin's own course navigation (if you loaded the same GPX as a Garmin course), GPS matching against the stored course, or elapsed distance. SETTINGS (watch data field settings menu) Vertical exaggeration: 2x, 3x, 4x Graph range: 500 m to 10 km, or fit to segment Current-grade window: 100, 200, 400 m Off-course threshold: 30, 50, 100 m Grade colours on/off Course: follow the server's current course, or pick a stored one Delete stored courses (with confirmation) to force a fresh download GOOD TO KNOW Independent, personal-use beta. The course server address is built in and currently points to the author's own server. On-screen labels are in Korean. First download needs a connected phone with Garmin Connect open; after that the watch works fully offline. Works best with the same GPX also loaded as a Garmin course for navigation, but runs on GPS matching alone otherwise. Requests only the Communications permission, used solely to download course files over a web request relayed through your paired phone.