OpenTrailPaper

OpenTrailPaper is the free companion app for the OpenTrailPaper e-paper bike computer — an open-source, sunlight-readable head unit you build yourself. The app handles everything that's awkward on a touch e-paper screen: planning routes, building offline maps, and reviewing your rides. Then it sends it all to your head unit over Bluetooth. No account, no cloud, no subscription. PLAN ROUTES — Search for any destination, preview the route on the map, and send it to your device as a GPX file. Turn-by-turn prompts guide you along the way — and your head unit follows the route even with no SD card and no signal. OFFLINE MAPS — Pick the area you ride and the app bakes offline map tiles straight onto the device's SD card. Roads, water, and parks render on the e-paper display wherever you go — no data connection required, ever. REVIEW YOUR RIDES — Pull your recorded rides off the device and see distance, moving time, speed, elevation gain, power, and heart rate, with your track drawn on the map. Every ride is a standard .fit file you can export and open anywhere. TUNE YOUR DEVICE — Adjust FTP, time zone, units, and backlight, and pair Bluetooth heart-rate and power sensors — all from your phone. Settings are saved to the device's flash so they persist across reboots. When a new firmware build is ready, update over the air with one tap. BUILT TO STAY OUT OF THE WAY - Works completely offline once set up — no phone or signal needed on the bike - No account and no subscription, ever - Nothing is uploaded; your routes and rides stay on your own devices - Fully open source WHY LOCATION AND BLUETOOTH — Bluetooth connects the app to your head unit to sync routes, maps, settings, and rides. Location (only while you're using the app) shows your position on the map, warm-starts the device's GPS so it locks on faster, and acts as a backup fix when the device can't see the sky. OpenTrailPaper pairs with the DIY OpenTrailPaper head unit. Build instructions, firmware, and full source are on GitHub.