A strange thing happened the other evening on my commute home. The heart-rate alarm went off on my Garmin. Now I’ve been reading fellow cyclists blogs and tweets talking about heart-rate based training – basically riding in zone 1 (50%-60% of max heart-rate) and zone 2 (60%-70%) to aid fat burning. I struggle with staying in these zones at weekends so have resolved to try and do it on my commute instead, which is easier to control on my fixie. Anyway, the alarm goes off when my heart-rate is above 190bpm! And I was pottering along at a very easy pace. Looking at my Garmin the HR was registering in the high 180’s and 190’s. After quickly discounting having a heart-attack, I adjusted the premium heart-rate strap in an attempt to correct it. In fact it went up to 225bpm – see graph above.
I’ve done a number of experiments now with the strap and have concluded that it is faulty. The problem is repeatable but unpredictable – you can ride for some time with a seemingly sensible reading and then it will spike upwards. But it is consistent in that it now happens every ride. Sometimes it reads 155bpm without the strap on.
A quick search on the Garmin forums and the internet proved the issue is not unique to me. It seems that plenty of people have reported the same problem. Note that this is the premium Garmin soft strap with the transmitter that clips onto the front via two press-studs that comes with the 800 (I think also the 500, 410 and 310 but I’m not sure), and not the hard plastic fronted one that come with the 705 or 305. It seems that Garmin will replace the straps – so I’ve contacted them and we’ll see how that gets on.
In the meantime the threads suggested that a better solution was to buy a replacement strap from Polar – the Polar Wearlink+ strap. It uses the same press-stud connectors and the transmitter from the Garmin just snaps right on. The Polar strap is good quality and more comfortable, and so far my real-world tests have proved that it is reading sensibly. The strap itself was £11 or so from Wiggle and well worth it, regardless of whether Garmin replace my original strap.
Hope this helps if you are noticing erratic Garmin chest strap HR readings.
Here is somebody else’s findings on the subject in a bit more detail, including pictures of the relevant items.