DPM5 and Garmin - distance discrepancies wrt intervals

[Dwalin]

Hi.
I have recently purchased a Concept2 DPM5-machine (firmware 20) and have noticed something slightly strange when doing intervals while paired with a Garmin FR610.

The short version: The Garmin grossly overestimates distance rowed after any rowing session involving intervals/rest periods on the PM5.

It seems the Garmin either calculates distance for the rest period interval as if I had kept constant speed throughout the rest period or adds that particular distance to the next interval.

The other day I did 500m intervals with 3min rest and the Garmin watch reported interval distance of ~750m [*].
Is this a known issue when using Garmin watches with PM5?

Is this a known issue? Are there any known workarounds/tricks I can use to get proper data logging?

Are there other good and low maintenance alternatives for data logging?
I have tried ErgData for android and had some trouble connecting to the PM5/beginning training session.
Should I be looking at using laptop and RowPro?

[*] N.B.: I am disabled and thus row slowly, could this be a likely cause for this issue?

Thanks in advance.

--
D

[Dwalin]

Update: This is also an issue on PM4 when using FR610 (I'd expect it's all compatible Garmins, but the 610 is the only one I have access to).

I have found what appears to be a workaround for getting accurate distances per interval:

When using interval/rest-function of the PM, make sure to press lap-button manually at the beginning of every interval after a rest period, making a lap of 0-1s at the beginning of every interval.
This dumps the wrong distance data into a <1s lap and clears the data for the following interval bout.

In my experience you end up with a <1s lap of several hundred meters that can be removed in applications such as training center (or gets automatically stripped by Strava).

[jamesg]

If the Garmin uses HR data to estimate distances, there will be calibration problems and it will add in what your HR does during the rest periods, if it doesn't know you have stopped.

The C2 provides data based on the flywheel behavior and its engineering parameters. For mechanical information (speed, time, distance, power etc), suggest you use only the erg as source.

As basic idea, the erg tells us what we have done, HR meters however refined tell us only how we react to doing it. So best practice could well be to use both and see what they say. There is no need to try to make them coincide in some way. The erg has removed the need to use HR as a proxy for work done, speed, power or whatever, we have a direct measurement.

[dexterdom]

Update: This is also an issue on PM4 when using FR610 (I'd expect it's all compatible Garmins, but the 610 is the only one I have access to).

I have found what appears to be a workaround for getting accurate distances per interval:

When using interval/rest-function of the PM, make sure to press lap-button manually at the beginning of every interval after a rest period, making a lap of 0-1s at the beginning of every interval.
This dumps the wrong distance data into a <1s lap and clears the data for the following interval bout.

In my experience you end up with a <1s lap of several hundred meters that can be removed in applications such as training center (or gets automatically stripped by Strava).

Thanks for posting this! I recently started using my garmin 610 with my PM5 and noticed that the distances for intervals was way off when viewing in Garmin Connect and Sporttracks. I'll use your method in my next workout. My only goal is to get data out of the PM5 into Sporttracks and I can't believe how many hoops I need to jump through for this "simple" task...

If Concept2 is listening you need to implement export to FIT or TCX format straight from the Concept2 utility, instead of that weirdly formatted CSV monstrosity...

Cheers