I have a Wahoo Tickr, which works well 99 % of the time. If I ride all day, the strap tends to slip. And every now and then I get erratic readings where the Tickr gets stuck at 204 bpm or something crazy. (When I have a heart rate of 204 bpm for real, I hope I’m in the hospital.) That doesn’t happen very often. Overall, I’m very happy.
I’d ideally like something like an Apple Watch, which also has an accurate heart rate sensor.
Ive not read the whole thread but how do you know 204bpm isn’t your max?
Iam 45 and the maximum I’ve hit this year 199bpm (96-98% of that is regular on turbore sessions and TTs on regular rides though I only hit a circa comfortable 170bpm) and my mate (the same age as me) regularly hits 200bpm +
Conversely though when I was about 30 my younger mate had a max HR of 170 something and he’s a phenomenal climber. We are all different and formula calculated methods can be way out.
IME, optical HR monitors don’t work very well during exercise, especially if they move around easily. That might be why your apparent HR seems high. It seems that it might be at least worth ruling this out before pursuing other explanations.
God no. That’s about 24 bpm too high. 
The Wahoo Tickr I use is a traditional electrode-based breast strap sensor, not an optical one. Heart rate getting stuck happens during exercise, so after the electrodes have been wetted with sweat.
That’s a fair point. I have a Praxis Zayante Carbon 1X on my gravel bike, and a SRAM NX1 on my MTB. I don’t think I’ll be upgrading that MTB to a carbon crankset in the future, though.
I find Heart Rate zones to be very valuable for outdoor riding without a powermeter.
From two seasons of working out inside with power & heart rate, I find my heart rate does not vary much at all from day to day etc for a given power. So I find going by just heart rate and RPE is plenty good outdoor on my mountain bike, pacing climbs etc
If this were the case, I would expect to see some HR data that gets above 190. As it stands right now, I have lots of data in the range of 42-189. Nothing 190+.
I do remember having my HR go above 200… in middle school.
It wouldn’t need to be both carbon, but the way the crank arms attach needs to be the same, obviously. And with MTB’s the cranks are often a different length than road/gravel bikes - stock mtbs usually have 175mm, and stock road 172.5mm.
I know what you mean, seeing the figure after a nice long steady build up like a TT is understandable but in the middle of a ride for a second or two is most likely a spike
Looking at your HR data below, periods of 90 mins in Zone 4 are not out of the question. But a lot depends on how you feel at that pace. If it’s comfortable and you could go on, then it’s probably Tempo.
I trained using HR up to this year. HR zones are just theoretical/ statistical abstractions. But you have loads of good HR data, plus the experience of knowing how it feels to ride that way.
I would say forget the formulas and develop your zones to be meaningful to you. With stop/ starts, hills/ flats, winds/ draft, not to mention cardiac drift - I think the actual bpm is less important than how you feel, and how you know a given HR is going to impact you.
Besides lactate threshold, I think the other important marker is your 2-4 hour pace. Call that the top end of Tempo. Then the range between them is steady state/ sweet spot (SS). LT is, say, equivalent to FTP (your notional 1-hour pace), so SS is hard but do-able. Experience lets you relate the do-ability to HR - at 170 I can last x mins, but if i drop to 168 it’s x+n.
If you do this you can customise the zones to meaningful things in your cycling.
