Open source · ESP32-S3 · LilyGO T5S3 4.7"

Open Source E‑Ink Bike Computer

Offline maps, GPX routes, FIT ride recording and BLE sensors on a 4.7" e-paper panel — fully standalone, no subscription, no phone required.

Set up your device → See what it does View source

CI builds · open source

01 — Take the tour

See how it works, tap by tap.

Step through the real on-device screens and see exactly where you touch the panel to get around.

02 — The companion app

The phone does the typing. The bike does the riding.

A free iOS app handles everything that’s fiddly on a touch e-paper screen — planning routes, building offline maps, and reviewing rides — then streams it all to the head unit over Bluetooth.

Route preview after searching a destination — **Plan a route**Search a destination, preview the route it draws, and send it to the device as GPX.

Rides list in the app — **Review your rides**Browse every ride you’ve recorded, then open one for the map, distance, power, HR and ascent.

Settings with a firmware update pending — **Tune & update**FTP, timezone, units and backlight — plus a one-tap over-the-air update when a new build is ready.

03 — What runs where

Everything you need on the bike. The phone just helps you set up.

Once it’s loaded, the head unit rides completely on its own — no phone, no signal, no account. You only reach for the app now and then: to plan a new route, add maps for a new area, or change a setting.

On the device — every ride

GPS tracking with speed, distance and a live map
Records each ride to a .fit file on the SD card
Turn-by-turn prompts along a loaded route
Pairs with heart-rate & power sensors over Bluetooth
Runs fully offline — no phone or signal needed

In the app — now and then

Plan a route and send it to the device
Build offline maps for a new area
Pull rides off the device and review them
Change settings and update the firmware

Have the hardware?

Flash it and load maps — all in your browser.

Flash the firmware over USB and bake offline maps onto the SD card, no app or command line needed.

Set up your device →