Setup Guide
Pair it once. After that, it's two taps before every ride. Pick your device below to get the exact steps.
Before Every Ride
Skip these and the first 5 minutes of your ride become a debugging session.
- HRM app installed on both iPhone and Apple Watch
- Low Power Mode off on both iPhone and Apple Watch
- Bike computer's companion app (Garmin Connect, Wahoo, etc.) fully closed on iPhone — swipe it away, don't just background it
Choose Your Device
Each guide covers first-time setup, the per-ride procedure, and device-specific quirks.
Not Sure If Your Device Works?
Check the compatibility list before you start — some older models can't connect, and it's better to know upfront.
How It Works
Your Apple Watch measures heart rate and sends it to your iPhone. Your iPhone broadcasts it over Bluetooth Low Energy — exactly like a chest strap — to your bike computer. Both devices are required. Neither works alone.
General Troubleshooting
Most connection problems have the same root cause: another app on your iPhone is quietly holding the Bluetooth connection to your bike computer.
Terminate the Companion App First
Close your bike computer's app (Garmin Connect, Wahoo, etc.) on your iPhone before starting HRM. Swipe it away completely — backgrounding it isn't enough.
Disable Background App Refresh for the Companion App
Go to Settings → General → Background App Refresh and disable it for your bike computer's app.
This stops it from silently reclaiming the connection while you're riding.
Connection Dropped Mid-Ride?
Go to your device's sensor settings and toggle the HRM sensor off and back on. Reconnects within seconds.
Frequently Asked Questions
My heart rate shows "--". What's wrong?
No recent heart rate data is reaching the app from Apple Health. Common causes: Low Power Mode is on, you just put the Watch on (give it 30 seconds), or Health permissions are missing.
Check at Settings (on your Watch) → Health → Apps → HRM. Grant permissions if missing. If it still shows "--", toggle the Heart Rate permission off and back on.
Do I need to press Start on the Apple Watch?
Yes — this is the most commonly missed step. Pressing Start begins frequent heart rate collection and keeps both apps running in the background. Without it, updates will be too slow or stop entirely.
Do I need to keep the iPhone app open?
No. Once your bike computer is connected, lock your iPhone or switch apps freely. HRM keeps broadcasting in the background.
Do I need to keep the Watch app open?
Yes. The Watch app must stay on screen during your ride for consistent updates. If it goes to the watch face, heart rate may slow or stop.
How long does the battery last?
No GPS means the Watch battery goes further than you'd expect. Tested on rides over 8 hours with ~30% remaining on Apple Watch Series 7.
Can I use another workout app at the same time?
No. Apple Watch only allows one active workout session at a time. It's HRM or another workout app — not both.
Heart rate only updates when I look at my Watch. How do I fix it?
Enable Background App Refresh for both HRM and the Apple Fitness app. Go to Settings → General → Background App Refresh on your iPhone and turn on both.