Show HN: Open-Source eInk Bike Computer

The device has a 4.7-inch e-paper display readable in direct sunlight. It includes an SD card slot for offline maps and ride logs. The hardware integrates GPS, capacitive touch, front lighting, a 1,500 mAh battery, USB-C, and Bluetooth 5 for heart-rate, power, and cadence sensors. Baseline runtime is about 7.4 hours with the light off. It lacks a pressure sensor, barometric altimeter, magnetometer, waterproofing, and its GPS module may struggle under canopy or between buildings. Interaction relies mainly on the touch panel, which can be difficult with gloves, and the hardware buttons are weak.