OpenBikeComputer

An open-source GPS computer for bikepacking.

Live browser demo · Documentation · Contributing

[!NOTE] This project is developed with extensive use of AI coding tools. Don't get out your "AI Slop" pitchforks just yet though. Any text you read in the software or documentation that sounds AI generated will be replaced once we get closer to releasing this project. The goal is that all user-facing text is 100% human-generated!

OpenBikeComputer is a fully open-source, bikepacking-focused GPS cycling computer. The main features and capabilities we are aiming for are the following (roughly in order of importance):

• Reliable and simple map-based tracking and navigation
• Uploading a route from the companion app should work every time (no BLE connection issues, no unreasonably low limit on point count in GPX files etc.)
• No subscriptions or accounts required for any of the features of the device
• Long battery life, ideally 4+ days between recharges, if you need to recharge it should work reliably with dynamo hubs that provide 5V
• Helps you keep your phone in your pocket by providing all the info you frequently check on the bike:
  • POIS (Shops, water sources, campsites etc.) near you and along the route (including opening hours), with the ability to create a route there on the fly
  • And a fun one: Mountain peaks around you (PeakFinder style)

This repository contains all the software and hardware files needed to build the OBC and the goal is to eventually provide kits that allow you to build the OBC yourself. The project currently is an active prototype, not a finished product and you can read about the progress of development in our Blog. Here are some peeks at the software and hardware designs:

Try the simulator

The simulator is the best way to explore the project without hardware. It runs the real device application in a desktop window and downloads the map, route, terrain, and ride data for the Grimsel Pass demo on first use.

Install Rust, Git, Python 3.14+, uv 0.8.17+ and just 1.57+:

git clone https://github.com/timohueser/OpenBikeComputer.git
cd OpenBikeComputer
cargo install just
just sim

First builds take a few minutes; fixture downloads are cached. just --list lists tasks; just --show TASK shows a recipe. Run ./tools/obc setup for the obc alias and completion. See the simulator guide for controls and rendering.

Roadmap

This is the current direction, not a release schedule.

Stage	Status
Shared application, offline maps, routing, ride recording	Available in the simulator and browser demo
iOS companion and BLE/USB transfer flows	Working with the development platform
nRF54LM20 development-kit prototype with the 240 × 320 reflective display	Running on hardware
Custom PCB and enclosure	In development
Integrated, field-tested bike computer	Next major milestone
Reproducible hardware build, assembly, and flashing guide	Planned when the custom hardware is ready

Current development platform

The hardware build uses the Nordic nRF54LM20 development kit and a Sharp LS021B7DD02 240 × 320 reflective memory LCD. It reads maps and routes from microSD and connects to the companion software over BLE and USB. The custom PCB and enclosure are still under development. KiCad sources are in hardware/; CAD sources for the enclosure follow later.

Repository layout

Path	Purpose
firmware/	Device application, rendering, protocols, storage, board image, and bootloader
host/	Host tools, map bakers, fixtures, and test support
planner/	Router, build tools, service, search, and tile worker
sim/	Desktop, web and phone simulators, host core, replay, feeder and benchmarks
builder/	Web and desktop builder, Rust/WASM core, USB transport, presets, and server
companion-ios/	SwiftUI companion app and shared iOS package
specs/	Normative binary, wire, and vector contracts
fixtures/	Scenario registry, source provenance, and fixture builders
data/	External data sources with their licences, regions, and environments
docs/	Public documentation, website, and project blog
hardware/	KiCad schematics, PCB layouts, footprints, and component models
tools/	The obc command, repository tools, and verification console

Cargo.toml lists the root workspace crates. The nRF54L board image, bootloader, Tauri desktop app, and sensor simulator are standalone Cargo roots. The architecture guide explains the boundaries.

Other open bike computers

OpenBikeComputer is not the only open source bike computer project! Here is a (non-exhaustive) list of some other cool ones this project is inspired by:

• IceNav — an ESP32-based GPS navigator with multi-GNSS support and both rendered and vector offline maps.
• OpenTrailPaper — an ESP32-S3 e-paper computer with offline maps, ride recording, and an iOS companion.
• Pedal Guru — a work-in-progress bike computer project for Raspberry Pi, RP2040, and ESP32 platforms.
• Pi Zero Bikecomputer — a Raspberry Pi GPS and ANT+ computer with offline maps, navigation, and FIT ride logging.
• bike-computer-32 — a low-cost ESP32-C3 mini-map with offline OpenStreetMap data, GNSS positioning, and GPX track overlays.

Contributing

Contributions are always welcome! This project is in the very early stages and many things are still a little chaotic and not well documented in many areas. Code is written almost exclusively using AI coding agents, but all the hardware design is fully human-powered. Help on that front would be especially appreciated. Please just get in contact with me if you want to contribute.

License

Software is available under GPL-3.0-only, except host/obc-data, which is MIT OR Apache-2.0 and depends on no GPL crate. Hardware design sources are available under CERN-OHL-S-2.0. Third-party notices are in the notice file.