Heart rate sensor keeps disconnecting


Til the last weekend I used Zwift in my Tablet (Galaxy A7) and the Companion-App an my Android (Galaxy S10+).
My bike (ICG 8) was always able to detect my heart rate sensor (Polar H10) via Bluetooth, my tablet connected also to the heart rate sensor via BT und got the cadence and watts form the bike.
The Companion-App also got the infos.

Now, I upgraded my setup and connected my old TV to my Notebook.
So, I’m using my Notebook with an ANT+ Dongle, for the heart rate.
My notebook also gets the cadence and watts data from the bike.
The Companion-App still gets the cadence and watts.
But, the heart rate keeps disconnecting most of the time, even if I’m only sitting in front of my PC.
Also the Companion-App looses now the heart rate sensor
At first Zwift finds the heart rate sensor via ANT+ and BT, but after only a few seconds the connection is lost. Then, after some seconds or minutes it reconnects, only to loose it again.
This happens on the PC (no matter if I connect the sensor via ANT+ or BT) and also on my Android.
The bike has no issues whatsoever.
When I set Zwift to get the data from the Companion-App, instead of the build-in BT, this also happens.
The distance between the heart rate sensor and bike computer is approx 30 to 80 cm (sitting to cycling out of the saddle), to the Android also 30 to 80 cm and to the PC (incl. ANT+ dongle) approx 3 meters.
What have I tried so far?

  • putted the Notebook closer to the bike
  • changed the USB-Port for the Dongle
  • checked the power options
  • removed all other BT devices (mouse, headset, etc.)
  • changed the Wifi channel of my router
  • deactivated my Wifi
  • bought a new ANT+ Dongle
  • reseted my hear rate sensor
  • even tried to persuade the sensor and Zwift on PC

Any further ideas?

Look at these signal loss:

Do you have a USB extension cable for the ANT+ dongle so it can be closer to you?


Yesterday, I bought one and tried it just now.
Now the heart rate acts more strangely:

About the first 30 minutes, the heart rate sensor stays most of the time connected.
Thenceforth all goes downhill…
First the connection between the heart rate sensor and the ANT+ Dongle gets lost, as usual.
It reconnects and looses several times and has some drops in the HR…
Then the connection seems to be stable again but the heart rate keeps dropping continously till it reaches approx 95 bpm.
After staying there for some minutes, the connection gets lost again, only to reconnect with a higher, but still to low, heartrate and then, the heart rate drops again continously, but to an even lower value (see graph).

The heart rate sensor (Polar H10) is able to connect via ANT+ and up to two BT-devices via BLE.
It connects to the bike computer via BLE.
It should connect to the ANT+ Dongle with my Notebook.
It should connect with my Galaxy S10+ —> with which connection?

After the ride I tried some things:

First, I unpaired the HR-Sensor from my Android.
→ The Companion-App looses the signal, obviously, but Zwift still shows the way to low heart rate while my Android keeps getting pairing requests from the HR-Sensor.

Second, I deactivated Bluetooth on my Android.
→ The Companion-App looses all sensor connections (HR, cadence, watts), Zwift still shows all data.

Third, I deactivated the option to connect to two BT-Devices via BLE in the Polar Beat App, so the sensor can only connect to one BT-Device.
→ This seems to work. The Companion-App still gets all sensor data, just as Zwift on PC and the bike computer. Maybe the HR-Sensor tried to connect to Android and PC via ANT+, to the bike via BT and also was connected via BT to all three devices, which doesn’t work?
I don’t know, but will watch this now closely.

Finally solved the problem!

I had to start Zwift first on PC, connect all sensors via ANT+ and BLE, than the Companion App.
Now the connection is stable.

Hi Sebastian, could you explain your fix a bit more? I think I may be having the same issue since the last game update. My heartrate monitor is usually connected directly to my PC running Zwift using ANT+ (I have a 4iiii Viiiiva HRM) and I am now seeing repeated drop outs although when I analyze the log file afterwards on Zwiftalizer I am not seeing these recorded. Switching to BLE doesn’t seem to fix anything. Are you suggesting that connecting your HRM via Companion was the fix that worked in the end for you?


sorry for the delay.
Unfortunatly it was not the order I had to start Zwift and the Companion App.
It was a bit more complicated:

My Spinning bike connects via ANT+ or BLE with my HR-Sensor.
When starting the bike-computer it shows me my HR-Sensor three times:

First, as Analog Heartrate-Sensor
second, as Bluetooth Heartrate-Monitor.
and third, as ANT+ Heartrate-Belt 15823

I never choosed the first option.
It Doesn’t matter if I take the second or third option, the bike connects properly with the HR-Sensor.

But, when I choose the BT-Option (I usually did), the HR-Belt connects to the bike and also tries to connect to my PC and my Smartphone. (used an BT device and connection finder app)
Now the bike-computer sends the sensor data (HR,cadence and power) via ANT+ to PC and Smartphone and the PC and Smartphone also are also getting HR-Signals via BLE from the HR-Sensor.

So first,I deactivated the option to connect to two BLE devices in the Polar Beat App.
And now, I only have to select the ANT+ HR-Belt 15823 when starting up the bike computer and everything’s fine.

I also have the problem with my garmin harte rate monitor disconection and re connection all the time. 10 to 15 times during an 1 hour work out.

Hi Paul, welcome back. This is Juan from Zwift. I understand how essential it is for you to maintain a stable connection with your heart rate monitor. Don’t worry. Let’s bring you back on track.

Dropouts are often difficult to pinpoint. Troubleshooting may vary depending on how you are paired, Bluetooth or ANT. Please refer to this article to get ANT+ and BLE overview.

Bluetooth, unlike ANT+, is a one-to-one connection. Your heart rate monitor may be paired with another app or device. On the other hand ANT works differently. Weak signal or interference is by far the most common reason for ANT drops and is due to the inherent weaknesses of ANT+ as a wireless protocol.

I’d like to suggest you take a look at this article to rule out scenarios and isolate the issue. There you also find suggestions on how to fix each one. If the issue persists, please don not hesitate to contact our support colleagues. We will be delighted to help you.