Open-source e-ink bike computer ships with GPS, skips altimeter
A Show HN post introduces an open-source bike computer built around a 4.7 inch e-paper panel that stays readable in direct sunlight. The board combines GPS, capacitive touch, a front light, a battery and USB-C on a single unit, adds Bluetooth 5 support for heart-rate, power and cadence sensors, and takes offline maps, routes, ride files and logs from an SD card. Firmware is installed from a desktop Chromium browser over USB, with no separate flashing tool needed.
The post is unusually candid about what the current hardware does not do. There is no barometric altimeter, so climbing is derived from elevation data baked into the map tiles rather than measured directly, which makes total ascent an estimate rather than a reading. The GPS receiver works but is a basic, single-band module; a modern multi-band module would lock on faster and hold a fix better under tree cover or between buildings. There is no magnetometer, so without a compass the map can only orient itself from the rider's direction of travel, meaning it cannot point the correct way while the rider is stopped.
On power, the measured baseline is about eight hours, and one specific build with a 1,500 mAh battery ran for roughly 7.4 usable hours with the front light switched off. The post notes that power-related work is ongoing, so newer builds may perform differently. Interaction leans heavily on the touch panel because the hardware buttons are weak, which the post says makes the interface fiddly to use with winter gloves or in the rain. Finally, the board ships bare with no seal or IP rating, so it needs its own case or bag before being ridden in wet weather.
No price, release date, availability or purchase channel is given, and the post does not name a specific replacement chipset for the GPS, magnetometer or altimeter, only that upgrades in those areas would help.
Key facts
- The board uses a 4.7 inch e-paper display that stays readable in direct sunlight, plus an SD card slot for offline maps, routes, ride files and logs.
- GPS, capacitive touch, a front light, a battery and USB-C sit on one board, with Bluetooth 5 support for heart-rate, power and cadence sensors.
- Firmware installs from a desktop Chromium browser over USB.
- Measured battery life is about eight hours baseline, with one 1,500 mAh build reaching roughly 7.4 usable hours with the front light off; power work is ongoing.
- The project openly lists its own hardware gaps: no barometric altimeter, a basic single-band GPS receiver, no magnetometer, weak hardware buttons, and no waterproofing or IP rating.
Why it matters
E-paper bike computers that stay legible in full sun and run for hours on a small battery are uncommon, and this one bundles that display with GPS, Bluetooth sensor support and offline SD card maps into a single open-source board. Just as notable is the format: the project's own post reads like an engineering changelog, stating what works alongside what does not, rather than a marketing pitch.
Who it affects
Cyclists and bikepackers who want offline navigation with long battery life and a screen that works outdoors, plus open-source hardware hobbyists who might build, modify or contribute to the design themselves.
How to use it
Maps, routes, ride files and logs load from an SD card, sensors connect over Bluetooth 5, and firmware is flashed from a desktop Chromium browser over USB rather than a dedicated tool. No price, release date or purchase channel is stated, so it is not yet clear how someone would acquire one.
How solid is it
The claims rest on the project's own measurements rather than third-party testing: a stated baseline of about eight hours, and a specific 1,500 mAh build measured at roughly 7.4 usable hours with the front light off. The post itself flags that power-related development is ongoing, so battery figures on newer builds may differ from these.
Risks and caveats
There is no barometric altimeter, so total ascent is estimated from map-tile elevation data rather than measured. The GPS is a basic single-band receiver that locks on and holds a fix more slowly than a multi-band module would, particularly under tree cover or between buildings. Without a magnetometer, the map can only orient from the direction of travel, so it cannot show the correct heading while stationary. Weak hardware buttons push most interaction onto the touch panel, which the project says is fiddly with winter gloves or in the rain. The board also ships bare with no seal or IP rating, so it needs a separate case or bag before riding in wet conditions.
“The board ships bare with no seal or IP rating, so it needs a case or a bag of its own before you ride it in the wet.”
— the project's Show HN post