Ant+ Garmin Heart Rate Strap connection gone after ~15 mins

Hi all,

I recently (last week) bought a new Ant+ dongle and a Garmin HRM-Tri heart rate monitor to also track my heart rate during Zwift workouts.

The initial pairing in the start screen works perfectly fine and I can connect the heart rate monitor easily via Ant+ (my Turbo is connected via Bluetooth). The two times I tried to use the heart rate monitor on Zwift, I lost connection to it ~10-15 minutes into my workout and could not get it back. When going back into the pairing screen after loosing the connection, the heart rate monitor is not displayed anymore.

I don’t think it’s a battery problem of the strap as it’s brand new. The strap also connects perfectly fine with my watch without any issues. Zwift also shows the Ant+ dongle as working/active.

Does anyone have an idea how I could fix the issue?

Thank you

Can it be that your phone is still connected via Bluetooth to the HR strap.

No unfortunately not, the HR strap only supports Ant+, so can’t connect to my phone.

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You mention that your strap connects with your watch. Is it connecting with your watch during your workout?

Doesn’t matter, ANT+ is a one-to-many connection.

@Jonas_Stenger I have used a Garmin Tri HRM for about 4 years with very little drop outs. You could be getting interference, how far away is your Ant+ dongle from your HRM. For reference I have mine right under the crank.

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Thanks Paul, that was what I was thinking too. The Ant+ dongle is ~ 3.5 ft/ one meter away from the HRM. Next time I can try moving it closer, but I guess I’m somewhat limited as it needs to be plugged into my laptop. Will give that a try and report back.

If anyone else has other ideas what the issue might be - please shout!

Thank you!

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Try a USB extension cable to get the dongle closer.

Thank you Paul! Quick update here: I used a USB extension cable and got the dongle pretty close (1.5 ft maybe) to the strap. Unfortunately, the issue persists.

Today, my HRM disconnected after ~6 minutes. Afterwards, Zwift showed the strap as connected, but without signal. I unplugged the Ant+ dongle and plugged it back in after a few seconds and the HRM reconnected with signal. I continued my workout, but ~15 minutes later it dropped again. I tried to unplug and plug back in, but no success this time and I continued my workout without the HRM (also because it’s a little interrupting to reconnect all the time).

One thing I noticed today during both dropouts (and also for the previous ones, but took it as coincidence): Zwift freezes/skips for a couple of seconds and then looses the HRM connection/signal. This makes me think that it’s rather an issue with either Zwift, the Ant+ dongle itself, or my laptop and not so much an interference issue?

Any other ideas/experiences?

Thanks all!

Not sure if any of this will help but…
even though it is new, it’s worth trying a new battery.
You could also try resetting the unit by removing the battery and touching the two contacts inside together. (often done by inserting the battery upside down. check on line first)
One other problem I have had in the past was my cycle clothing was causing static which was interfering with the signal. I have also had a HRM belt look perfect but was in fact faulty.

Thanks Troy - I tried that and actually also tried a different HRM strap, but both dropped after ~ 15 minutes. Again, right before loosing connection Zwift skips/freezes.

Not sure how to solve this now.

Hi Jonas,

I’m guessing that this may have something to with your issue. If you are able, can you hard wire your computer/device to the internet? This would hopefully stop the dropouts you are experiencing. I’m a bit out of my depth now really.

Thank you Troy - also digging this thread out again.

Unfortunately, hard wiring my computer to the internet doesn’t help either and the connection drops.

The skips I’m experiencing also only happen when connected to the HRM and seem more like in-game glitches than (internet) connection issues. For example, during these skips my avatar disappears and I’m seeing my bike only for a few seconds until everything stabilizes, the avatar re-appears and my HRM drops.

Interestingly, I noticed today that my Smart Trainer connected via Ant+ (and not Bluetooths as it usually does) and stayed connected the whole time without issues.

I don’t really know what else to do to fix this, but I guess getting a Bluetooth HRM might be a good first step, unless someone from the Zwift support team has an idea.

Thanks all for chiming in though!

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Hi Jonas,

Your not the only one getting this issue,
I am running a Samsung galaxy tab s7 with an ANT+ dongle & keep getting a HRM drop out at about 15-20 min of being on zwift,

When i use the same ANT+ dongle on my PC no issue as all so ruled out that it could be a fault with the dongle.

I never noticed until i read your post that the screen does seem to freeze up then jump forward by a few seconds just as the drop out happens.

Hopefully this is something we can find some answers too