# HRM Heart Rate Monitor

> HRM is an iOS and watchOS app that streams heart rate data from your Apple Watch to cycling computers and indoor training apps via Bluetooth Low Energy — replacing a chest strap. Just your Watch and iPhone, gear you're already carrying.

## App

- [App Store](https://apps.apple.com/app/apple-store/id1671488058): Download HRM ($7.99/year, 7-day free trial). Requires Apple Watch (watchOS 8+) and iPhone (iOS 15+).

## Setup Guides

- [Guides overview](/guides): Choose your device — Garmin Edge, Wahoo ELEMNT, Hammerhead Karoo, indoor training apps, or other BLE-compatible computers.
- [Garmin Edge](/guides/garmin): Step-by-step first-time setup and per-ride procedure for Garmin Edge 130, 540, 840, 1040, 1050, Explore 2. Includes phone connection limitation workaround (terminate Garmin Connect before each ride).
- [Wahoo ELEMNT](/guides/wahoo): Setup for ELEMNT ROAM V1/V2/V3, BOLT V1/V2/V3, ACE. Same phone connection limitation — terminate Wahoo app before connecting.
- [Hammerhead Karoo](/guides/hammerhead): Simplest setup of any major cycling computer — Karoo has no companion app competing for Bluetooth. Covers Karoo 2 and Karoo 3.
- [Indoor Training Apps](/guides/indoor): Setup for Zwift, TrainerRoad, ROUVY, FulGaz, TrainerDay. Key constraint: HRM must run on iPhone; training app must run on a separate device (iPad, Apple TV, Android, or computer).
- [Other Devices](/guides/other): General BLE pairing procedure for Bryton, Sigma, Lezyne, Bosch, and other BLE-compatible devices.

## Compatibility

- [Device Compatibility](/compatibility): Full list of supported and unsupported cycling computers and training apps, with status indicators and notes on known limitations.

## Frequently Asked Questions

- Do I need to press Start on the Apple Watch? Yes — required for frequent heart rate sampling. This is the most commonly missed step.
- My heart rate shows "--". What's wrong? No recent data is reaching the app from Apple Health. Check Low Power Mode, Health permissions at Settings (Watch) → Health → Apps → HRM.
- Do I need to keep the iPhone app open? No — once your cycling computer is connected, HRM broadcasts in the background.
- Do I need to keep the Watch app open? Yes — the Watch app must stay on screen for consistent updates.
- How long does the battery last? Over 8 hours tested on Apple Watch Series 7 with ~30% remaining (no GPS used).
- Can I use another workout app at the same time? No — Apple Watch allows only one active workout session.
- Heart rate only updates when I look at my Watch? Enable Background App Refresh for HRM and Apple Fitness at Settings → General → Background App Refresh.

## About

- [About](/about): Why HRM was built — the developer wanted to ditch a chest strap and use an Apple Watch on rides instead.

## Legal

- [Privacy Policy](/legal/privacy)
- [Terms of Use](/legal/terms)
- [Imprint](/legal/imprint): Published by App Lane OÜ.