---
title: "Gran Fondo, a cycling and running tracker for iPhone"
language: en
topics: ["AI", "apple", "bike", "creating", "data", "design", "gran fondo", "health", "heart", "minimal", "programming", "running", "sensors", "sport", "watch"]
full_article_url: https://willem.com/en/2024-05-11_developing-a-native-ios-app/
---
# Gran Fondo, a cycling and running tracker for iPhone

*A workout tracker without ads, accounts or data selling.*

> In 2024 I built Gran Fondo, a native iOS app that records rides and runs with Bluetooth heart rate, cadence, power and speed sensors, saves everything to Apple Health in full detail, and needs no account, ads or data selling.

I wrote Gran Fondo natively in Swift with SwiftUI, because a workout tracker must be extremely energy efficient and integrate deeply with iOS. It connects to heart rate, cadence, power and speed sensors over Bluetooth and supports multiple sensors, which helps if you ride different bikes.
Everything is stored in Apple Health in maximum detail, including routes and individual power, cadence and speed measurements, so apps like Strava, WHOOP and HealthFit can analyse the recordings. Mounted on the bars with QuadLock the iPhone works as a bike computer, showing live speed, power and heart rate plus graphs built with Swift Charts, switchable from the last minute to the whole workout.
There are no ads, no accounts and no data selling. The app is free to try and the payment screen can always be dismissed.