Show HN: Open-Source eInk Bike Computer

OpenTrailPaper is open-source firmware for the LilyGO T5S3 e-paper display that turns it into a DIY bike computer capable of GPS tracking, offline navigation, recording rides to FIT files, and connecting to Bluetooth sensors. The device works independently after maps and routes are loaded, with an optional iOS companion app for route planning, file transfer, and firmware updates. Currently a development project, it offers a sunlight-readable display and long battery life but trades off features like barometric altitude sensing and advanced GPS capabilities.