Show HN: Open-Source eInk Bike Computer
Points and comments are a snapshot, not live.
OpenTrailPaper is DIY e-paper firmware for the LilyGO T5S3 board, functioning as a bike computer.
OpenTrailPaper is firmware for the LilyGO T5S3 4.7" E-Paper PRO board. It displays ride data and offline maps, follows GPX routes, records FIT files, and connects to Bluetooth sensors. An optional iOS companion app handles route planning, map building, ride transfer, settings, and firmware updates over Bluetooth. The device works without a phone during rides. Currently supported only on the LilyGO board, it is a development project with tradeoffs: no barometric altimeter (climbing derived from map tiles), basic GPS, no magnetometer, about 8 hours of battery life, weak hardware buttons, and no waterproofing.
What commenters are saying
Commenters praised the project as "great" and "really cool," especially for its eInk display and ANT+ support over BLE hardware. There was split sentiment: some appreciated a separate device to save phone battery and avoid damage, while others preferred using a phone with a mount. Multiple users raised concerns about weather sealing in rainy climates like the Netherlands, though one shared positive experience with proper DIY waterproofing. Several noted ANT+ is effectively dead in Europe due to encryption regulations, with new devices moving to BLE.
One commenter built a similar iPhone app with voice feedback and thermal management, though noting different tradeoffs versus eInk. Others discussed eInk's advantages in direct sunlight compared to LCD screens.