OpenTrailPaper
1 commentThe first launch from OpenTrailPaper
OpenTrailPaper
Open-source firmware for a DIY e-paper bike computer
#3 of the day · 13 Sep 2026
OpenTrailPaper is firmware for the LilyGO T5S3 4.7-inch e-paper board that turns it into a bike head unit: offline maps, GPX route following, FIT recording at 1 Hz and Bluetooth sensors for power and heart rate. You buy the board and a case yourself. A companion app for iPhone and Android plans routes, builds offline map tiles and moves rides off the device, but once maps are loaded the head unit rides without a phone. No account, no subscription.
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A bike computer is a GPS, a screen you can read in sunlight and a battery that lasts a day, and e-paper is the screen that was always right for it. That the commercial ones never used it says more about supply chains than about cyclists.
What makes this a real product rather than a weekend firmware is the companion app and the flasher: the path from a bare board in a padded envelope to a working head unit is written down and short. The catch is in the tagline — you protect the board yourself, and rain is real.