Before I replace my Garmin HRM3-SS Ant+ Only

Hi Guys.

Bought a MEKBELT SM36 Indoor Bike which is awesome.
I really like that bike.

It has all sensors included for Cadence, Power (Watts), Speed and it connects directly and instantly to the Zwift App on my IPad.
Never had a connection problem.

I started to wear my Garmin Fenix 5X with my Heart Rate Monitor HRM3-SS, which I bought when I first bought my VivoSmart watch.
Yes, I know, it was a long time ago. It is ANT+ Only.

And then yesterday I saw that I can download my training into Garmin Connect, which is great.

Everything seem to be there…but the HRM results.
They are on a two separate training in Garmin Connect.

Is there a way to send my HMR3-SS ANT+ Only Data to Zwift on my IPad ?

I see that I can use a ANT+ to Bluetooth dongle
I’ve found one dongle on Amazon by searching “ANT+ to Bluetooth USB”
but they all say it is for “It is for Windows and Mac, but not Android or iPhone”.
So I think it wouldn’t work with IPad.

So do I really need to buy a new Garmin HRM-DUAL that actually have ANT+ AND Bluetooth ?

And will it work ?

Thanks guys.

As far as I know, iOS/iPadOS doesn’t have the necessary smarts to use ANT+. Beyond the hardware, the OS needs some kind of driver/stack to act as a go-between.

There are ANT+ to Bluetooth bridging devices (4iiii Viiiiva HRM and NPE-CABLE pod), or you could just buy a new HRM that has ANT+ and BLE.

I’m a fan of the Polar H10 for reliability and a replaceable strap. NOT a fan of Garmin HRMs as I’ve had several die long before they should have. (I do own a new HRM-Pro+ as it has a battery door that’s supposed to solve the reliability issues)

are you having a double entry in Garmin connect due to your HRM? I don’t really get how the HRM could create a double activity. That you would record the activity from your watch and have it uploaded from Zwift yes, that would do a double, but the HRM?

Nevertheless, yes you need another HRM, as the one you are currently using with ant+ won’t connect. The HRM Dual will do, or a Pro or a Pro+.

I have 2 Pros, 1 run and 1 swim and never had any issues after replacing the batteries several times they all work perfectly fine.
Good thing with the Pros you can start the activity on your watch and remove your watch it will save all data (including steps) on your HRM directly…

I wear my Garmin Felix 5X with my HRM3-SS, which work great.
So my watch sends my HR data to Garmin Connect.
When I start my watch at the same time as “Let’s Go” in Zwift, after the training, I can download the Zwift fit file and import it into Garmin.
I just discover that I can establish a “ Connection” with Garmin Connect inside Zwift so I have some exploration to do.
Once they are both in Garmin Connect, I’m trying to find a way to migrate HR data into my Zwift data I just imported inside Garmin Connect.
This way, I wouldn’t have to buy a new HRM.
We’ll see, I’m chatting with Garmin. Still waiting for their response.
I wouldn’t want to throw away myHRM, it is still good.

I’m still unsure…

So your HRM is connected with ant+ to your watch, and you record a running activity on your watch.

The HRM can’t send data to Garmin Connect directly.

When you cycle on Zwift, you don’t have any HR data displayed, as you can’t connect your HRM to Zwift, am I right?

I understand you want to have your HR data into the Zwift activity, but you mean, on Zwift, not on Garmin Connect?

Thing is, the fenix 5x can send HR data, so you can search in the HRM pairing menu your watch in order to get HR data in Zwift while you are cycling.

Migrating HR data in the Zwift fit file won’t bring you anything, you can ignore that. It won’t go in Zwift afterwards anyway. You need to record it while you are zwifting.

So either you set your watch to broadcast HR data and you pair then your watch to Zwift, or you get an ant+ dongle that will allow you to pair your HRM directly to Zwift… You wouldn’t need to change your HRM but just buy an ant+ usb dongle.

Weirdness can be encountered trying to merge Fit files. I tried to do some data analysis of two Fit files of the same workout, but the timebase was completely off for one of the files. For some insane reason one Fit file started at 0:0:0 for the ‘real’ time, and when trying to combine the files, I had one ‘ride’ that stated at exactly midnight, and the other than started at around 16:00. Comparison was impossible unless I based it on elapsed time, which I couldn’t using the software at the time. Yeah, weird…

In programming and data analysis, never assume something is ‘easy’. :anguished:

Which software did you use to merge fit files? Using FFRT it’s definitely going well, in doing that for more than 2 years now always working perfect!

I was looking for something ‘free’ as I didn’t need the functionality for more than a few workouts.

I was using DCRainmaker’s data analyzer to visualize the data. Great app but I couldn’t find anything to help me fix the timebase issue. I was aware of FFRT, and found a couple of other apps that claimed to allow Fit file repair, but none of them seemed to work, plus I’m on a mac, and the choices were very limited. I even tried an XML utility, and it was way more complex to get the data massaged enough to have it work. I should have bought FFRT I suppose. Life just moved on.

From the guy that wrote FFRT. Yeah, there are a lot of changes and weirdness that ends up in a Fit file from what I found. Like how to import Peloton Fit files into Garmin Connect. Peloton does some things that Connect chokes on.

I don’t live by this project but I think a reasonable price for the tool is a fair way of


Have you tried to use to move the time stamp?

You can use to analyze the data for free.

Thanks. I had no idea that ZP would do that. I’ll look into it.

It was a short ‘what the heck is going on’ type of question. I was able to do each file separately and see what was going on. It was very early this year so the details aren’t important. I got into the workings of Fit files and found the ‘rules’ were more like guidelines. Too funny…

I received a lot of answers.
And it seems that I didn’t explain myself the right way.
I have a MekBelt SM36 Indoor bike that already have cadence and speed sensors and Zwift detect them right away.
My HRM3-SS is only ANT+.
Yes it is connected to my watch ( Garmin Felix 5X)
So after a ride, I sync with Garmin Connect with my watch and download my fit file to be able to import in in Garmin Connect.
So I have 2 activities in Garmin Connect.
For the same activity.

I thought I could merge the HRM data to the Zwift data once in the Garmin Connect. Not before so I understand that the graph data won’t be synchronized by anyway.

Thanks to you all for all the support but I will buy a Garmin HRM-Pro Plus and it will be resolved. The goal is to ride not to spend hours coding, decyfering data, etc.

You have 2 activities in Garmin Conenct because Zwift is connected to Garmin Connect :wink: So from what you say, I understand you have for the same ride 1 activity from Zwift and 1 activity from the watch. That’s what I meant with double recording. Zwift sends the activity to Garmin, and because you record an activity with your watch, Garmin has another one in. I have the same :slight_smile:

But no you can’t merge the two datasource (ie the two fit files). If you want to do that, only FFRT can do it (and merge many other things too, like GPS trace).

But you are right, idea is to train instead of spending hours programming stuff haha. Enjoy the ProPlus (or a Pro, same tech inside, just the battery compartment is with screws on the Pro, no screws on the Plus, but the Pro might be less expensive :wink: )