Garmin 500 reports HR whilst not wearing HRM

dabber

I've just replaced my Holux gps with a Garmin 500 and so far I'm very pleased with it.

However a question... the other day I paired my Holux HRM and Cadence sensor with the Garmin. This was easy and seems to work fine. Today I went for a ride but never bothered to put the HRM on but on downloading the ride Garmin Connect showed a reading for HR. No graph but just the summary "Avg HR" and "Max HR".... just a couple of bpm between them.
Is this just an anomaly because I never bothered to turn off the pairing. Of course, these spurious readings have transferred across to Strava as well. No big deal but I'm just interested.

monkimark

Could you have picked up somebody else's HR as you rode near them?

dabber

No chance of that, I was riding on my own.

clogg

Did you re-set the unit before your ride today ?. It may be just the residual readings from when the hrm was paired if a new ride was not started.

dabber

I guess that's a thought but (I never reset it)... the actual Avg/max numbers it gave were 137/139 and when I paired it I was just sitting down in the lounge and I'm pretty sure I was down in the 60's

stevewj

I think 500's are developing a sense of humour - mine has begun to randomly turn on a new lap - not a prob on a steady run but not helpful when in the middle of a session of intervals. I've just re-booted it to see if I can get rid otherwise back to Evans/Garmin as I have only had it six months and used for a month or so.

dabber

I've done a bit more investigating....
Although the HR chart on the summary page showed no activity, when I expanded it there appears to be a spike at about 13.76 to 13.77 miles going from 139 to 137 bpm. This is the only registered HR activity but enough to create the summary numbers.
I'm not sure what would have caused this. The bit of road is not among housing but is probably about quarter of a mile from crossing over the M3 motorway... phone masts etc?? who knows.
The only other thing I vaguely remember is that I would have been going up this hill at the time and there was another cyclist coming down the hill (we acknowledged each other) at about this point. Could I have got a signal from him? The road is reasonably wide so we never passed close to each other.
It's a mystery. :?

dabber

I tried it with the HRM on today and all was fine. I had a couple of spikes (220+bpm) but other than that all was fine.

I see that I can sort of correct those spikes in the Garmin Connect summary but the 220 pluses show in Strava as my max HR. I can't see anyway to fix that?

dw300

I've heard people say the spikes can be cause by static caused by cycling jerseys. Usually early in the ride before you get a sweat on which might make the sensor contact better. Not sure how to avoid it though.

Do you wet the sensors pre ride? The other cyclist could have been the cause but you'd expect the device to not search if you has already paired with a specific sensor. ANT+ has a pretty decent range.

sungod

^ this

really wet the sensor pads before fitting, also make sure the strap is tight enough, if it is loose and dry the readings can be all over the place

range is typically 10-30m, picking up other riders' sensors is not unusual, the likelihood of spurious pairing depends on implementation, if the garmin uses non-extended device numbers there are only 65536, so there will be many sensors with duplicate numbers

dabber

Thanks dw300 and sungod. In the past (using the Holux) I have wetted the sensor pads but on this occasion I must admit I didn't. In fact I have got a tube of electrode gel. The spikes I got were early on in the ride. I'd like to have been able to correct the entry on Strava but I can't see anyway to do that. Perhaps by asking the helpline folks but I don't want to pester them with this.

Interesting you say the range is 10 -30 metres. When I passed the other rider it would have been within that range but that would have for an extremely short time as we were going in opposite directions... him downhill at probably 30mph, me uphill at around 13/14 mph. A very short for the sensor and gps to have linked.

dw300

Spikes that Ive seen are almost always in the first 5 mins.

You can crop a Strava ride, but you'll loose all the data that you crop.

You can manually edit the file from the Garmin in a text editor (you might have to upload to Strava and download and edit a GPX or TCX), but there will probably be data for every 1-3 seconds of the ride and knowing what to change can take some patience.

There might also be repair tools .. https://www.google.co.uk/search?q=editing+a+.fit+file&oq=editing+a+.fit&aqs=chrome.1.69i57j0l5.4730j0j7&sourceid=chrome&espv=210&es_sm=119&ie=UTF-8

dabber

Thanks for that... much appreciated.
Yes, the spikes I referred to pretty much match your experience... the first was after about 2 mins and the second at 7min 30secs. I realise I could crop in Strava but I don't really want to do that.
I've looked at the files witha text editor but that looks like a painful exercise. However, I have had a look at the link you provided and I saw a couple of options although one looks a bit expensive. Thanks again.

Oh, btw, I went for a ride this morning, put on plenty of electrode gel and had no spikes.