Over the years I’ve put up with wildly inaccurate heart rate numbers in dry “windy’ weather (think long descents) where Polar, Garmin, and Wahoo would show my hr wildly high, 220+ where my max is 176. Never happens with a heavy jacket or if I’m soaking wet from sweat or rain. As soon as the descending is over, the hr goes to where it should be within one minute. I’ve tried dielectric grease all over the sensor with little improvement. The one commonality is that I have always worn wool sleeveless, tight lightweight base layers under my jerseys. I do have a couple of synthetic base layers on the way as a test. Does not matter if the jersey over the base layer is fully or partially zipped or zipped at all. I cannot be the only person to see this behavior? Anyone find a solution besides dealing with inaccurate max hr numbers?
I think this is static electricity building up. I could get it occasionally during the dry winter months wearing a synthetic base layer, but I haven’t tried wool before. I think some fabric softeners will reduce static, but I don’t know much about their effect on wool
Fabric softeners are generally a bad idea for performance fabrics for athletic wear. The coat the fibers and keep then from wicking as designed.
I’d think electrode gel would work better than dielectric grease.
Yip….almost certainly static electricity. Electrode gel won’t help much because the static electricity is between the HR pod and the clothing, not between you and the strap….but i can help a bit.
You can try wetting that area of your kit with water and that should help. You can also try rubbing the HR pod with a dryer sheet right before your ride. I have seen some reports of that helping, but never tried it myself.
A classic problem. Try an optical HRM.
We used to call this “flappy jersey syndrome”, back in the mid 2010s when the Garmin HRs were particularly guilty of this offence.
I’ve got a V1 Wahoo HRM that is still going strong after 10-ish years and it has never read high, like my old Garmin used to. Not saying it’s not possible and sounds like the OP has an unusually high electrostatic “aura”. Experimentation sounds like the way to go but as others have suggested, its probably just easier to get an optical HR that completely avoids the issue but not relying on electric signals.
I get this a lot with flappy jerseys. My answer has been a tight baselayer … I don’t wear wool, so can’t relate to that aspect.
A classic problem. Try an optical HRM.
Except that introduces different issues that can result in inaccuracies. Chest straps detecting the electrical pulses of an heart beating are well establish as the most accurate method of measuring heart rate during exercise.
Until, as experienced repeatedly above, it isn’t.
Until, as experienced repeatedly above, it isn’t.
Nothing is perfect. My point was that optical sensors are known to be more susceptible to issues than chest straps. In my experience, chest strap issues, when they do occur, tend to be more dramatic and obvious (way over, way under, or nothing), whereas optical seems to be more subtle in its inaccuracies, and so I question the reading all the time as failure isn’t as clear. I’d rather have something work correctly majority of the time and then when it doesn’t be able to say ‘well that’s clearly wrong’ vs ‘that looks a bit odd, but is it?’.
I guess this is one area where wearing a bra is an advantage 
To anyone that may come across this post I believe I’ve found my answer and it comes down to material. If I’m wearing a wool base layer (granted I have half a dozen all from the same manufacturer) that are 53% wool and 47% polyester, my HR readings go nuts as described in my first post. I’ve tried two other base layers that are mixes of polyester, Lyocell, and Spandex and the HR numbers are what I would expect. Certainly not a scientific experiment but again, I can turn the behavior on or off by changing base layers.
This!
I haven’t suffered the described problem but always found the traditional garmin / wahoo chest strap HRMs last 2 or 3 years. I now use a Polar Verity arm optical sensor has it’s never missed a beat. Also rechargable, so no landfill batteries.
Simon
I wear wool base layers regularly in the winter, but they are usually under a winter jacket or gillet, so I’ve not had any problems.
I’ve found that optical sensors on arm bands are worthless, especially in winter. I would get readings of HR in Z1 or below even as I was going up a long gradient in high Z2 or Z3. Maybe they’re more effective for runners who are swinging their arms.
It could be the case of the poly in the wool as a blend, but high % wool shouldn’t have anywhere near the static electricity problems because it’s hygroscopic, so it will hold on to a small amount of moisture while still feeling totally dry and that moisture will make the wool slightly conductive allowing charges to dissipate. Polyester is a great electrical insulator, because it doesn’t absorb moisture… the blend of the two together may make the situation worse. Use 100% wool, if you like wool base layers/warmers.