Huge heart rate zone discrepancy due to weather

Hey everybody,
so I went out yesterday for a 3h high Z2 power ride and my heart rate was 20! bpm higher than on the trainer for the same wattage (a real steady Z2 ride, not just comparing avg. power). The weather was a windy 5°C, but I still had a tent-effect due to waterproof jacket. The decoupling though was as low as 2.2% and my RPE was just on point maybe even lower than for the same trainer ride. I would expect maybe 5-10 bpm higher outside than inside due to traffic, more muscle activation because of bike stability control. So has somebody made the same experience with this huge mismatch in the heart rates. Would you say this is due to the cold weather or more due to my tent-like climate.

Thanks and have a good day!

I’ve never closely looked at HR but I have looked at the watts in blustery conditions and felt I was putting in a lot more effort to achieve them compared to indoors :thinking:

Yeah this is what I read most of the time and is the reason why I made a new topic. Because I think this doesn’t fit to something I have read here before.
Even despite this ride being 2000kJ it felt easy all the way to put the power down. Also my respiratory rate was not elevated compare to this insane high HR response.

I’ve never experienced it, but I’ve seen people say that a flapping jacket has driven their HR monitor crazy (static, perhaps?). Maybe that explains your data?

This is a very general observation over decades…All things equal the colder the temps the lower my HR.

Yup this is pretty much what I thought, what happened was the opposite… So maybe @old_but_not_dead_yet is right with false readings of HR strap. Might try this indoors on the trainer with the shirt I used yesterday. Or I actually overheated under the cloths and did not really notice it.

1 Like

Yes, cold weather is one thing. Body temp is another.

I’ve never experienced HR error other than very temporary spikes under high power lines. Nothing that would lead me to think the HRM was reading high/low for hours. JME

1 Like

Yes I think you are right. It would rather be spikes with the HRM.
Then I guess I boiled in my own sweat and this is why I had such a high HR. Rain jacket not a good Idea I guess. Lets try what a ride with colder clothing shows.

1 Like

@wlcycling if the battery in my HR monitor is low & I go out in cold weather sometimes it will give bad readings. Always too high or just nothing. Before the battery goes…always get some high readings. Sometimes alarmingly high. :smiley:

Maybe it’s time to replace the HR strap battery?

Significant cold drains batteries. As noted above, I’d try changing the battery before anything else

So coming back after looking at the data a bit more it just seems like I have a significant higher HR outside. During VO2Max intervals im holding 190+ easily. Inside my HR seems to be supressed by 10-15bpm. Im doing high Z2 stuff, it is feeling pretty easy also after 3h, still my HR is averaging 150-160 for this stuff. So seems normal for me. Maybe after covid stuff I get a proper lab test as im interested in it.

1 Like

That’s a whopping big difference if the work rate is the same. Wow. Very interesting.

Do you use the trainer’s power meter inside?

Inside it is a wahoo kickr core, outside it is a power2max spider. As my RPE and fatigue is quite same I guess they are pretty close but I still wan’t to test the PMs against each other. And a discrepancy of like ±10W would not rise my HR that much.
But hope I find time to compare PMs soon.

I have a Kickr 2017 (wheel off), it was the model before the Kickr core. After some testing I determined there was a discrepancy between the Kickr power and Stages power meter. Therefore inside on the trainer I only record the Stages power meter. If you are using Erg then TrainerRoad’s PowerMatch will record P2M power.

My guess is that part of your HR discrepancy is due to using 2 different power meters. I agree that a 5-10bpm difference between indoor and outdoor is acceptable, however you really should use the same power meter in order to use that rule of thumb.

Checked if this is the fault and compared my two powermeters. They are very very well in spec with each other. Work and TSS is within under 1% difference, with the P2M on the higher side, which I say is logical due to origin of data. I did not use the powermeter comparison tool, made it with comparing lap data on So yeah I guess my cardiac system just goes havoc outside, maybe the high discrepancy is because I still carry a decent upper body musculature from my gym background (meh, bad for cycling, but they are shrinking lol) or due to traffic. So I will just ignore heart rate and go by power and feeling and watching my fatigue status. As long as those kJ are flowing all is good I guess haha.