Cycle Star

A private e-bike savings tracker. One big START button on the phone, and a dashboard that adds up what riding instead of driving has saved: parking not paid plus fuel not burnt.

Dashboard overview with a goal progress ring, total saved, trip count, distance and the latest trips, using invented data — The dashboard overview, showing invented trips.

Android trip summary showing a saving of $1.77 with parking and fuel breakdown — The app's trip summary, from the debug simulator.

The pieces

Android appFollows a ride with GPS, finds the stops, and finishes the trip by itself when you get home.
- Kotlin
- Compose
- Room
DashboardA Worker and D1 database that stores trips, recalculates the savings and charts them.
- Cloudflare Workers
- D1
- JavaScript

How they fit together

The saving per trip is the parking you did not pay for, at a configured hourly rate for the time spent at each stop, plus the fuel a car would have burnt over the same distance, at the current fuel price.
The app records trips to a local database first and syncs them when there is a network. The Worker repeats the savings arithmetic on its own and ignores any figure the client sends, so the two cannot drift apart.
Sync needs two things: an edge credential for the Worker's Cloudflare Access policy and a Google sign-in that the Worker checks against an allow-list.

The screenshots use invented data.