I rode a very hard century ride today. A lot of solo gap bridging and some horrible starting position led me to push very hard for a lot of the race. I was very surprised with the info from my HRM, which I paid zero attention to throughout the race. Here's my zone stats based of Friel's lactate threshold zones for me:

Max HR - 188, LTHR - 175
Zone 1 - 00:20:45 60-75% MHR
Zone 2 - 01:01:23 76-82% MHR
Zone 3 - 01:33:07 83-88% MHR
Zone 4 - 01:47:46 89-93% MHR
Zone 5 - 00:17:39 94(LTHR)-100%
Avg HR - 160, Max HR for the ride - 181

I was surprised by having 17 almost 18 minutes above lactate threshold. There was a lot of pacelining which would explain Zone 2 times. I had a good amount of stop and start time at the beginning and toward the middle, so that explains zone 1 times. The first 10km was a high zone 4 and occasional zone 5 sprint to catch the lead group when I'd look down at the HRM. And a lot of climbing (just over 6000 feet).

I rode a very hard century ride today. A lot of solo gap bridging and some horrible starting position led me to push very hard for a lot of the race. I was very surprised with the info from my HRM, which I paid zero attention to throughout the race. Here's my zone stats based of Friel's lactate threshold zones for me:

Max HR - 188, LTHR - 175
Zone 1 - 00:20:45 60-75% MHR
Zone 2 - 01:01:23 76-82% MHR
Zone 3 - 01:33:07 83-88% MHR
Zone 4 - 01:47:46 89-93% MHR
Zone 5 - 00:17:39 94(LTHR)-100%
Avg HR - 160, Max HR for the ride - 181

I was surprised by having 17 almost 18 minutes above lactate threshold. There was a lot of pacelining which would explain Zone 2 times. I had a good amount of stop and start time at the beginning and toward the middle, so that explains zone 1 times. The first 10km was a high zone 4 and occasional zone 5 sprint to catch the lead group when I'd look down at the HRM. And a lot of climbing (just over 6000 feet).

Aren't Friel's zones based on "LTHR" and not max heart rate? Do you really know your max heart rate? Basing zones on LTHR accounts for changes in fitness.

1 - 65-81% LTHR
2 - 82-88% LTHR
3 - 89-93% LTHR
4 - 94-100% LTHR
5a, 5b, 5c - 101-106%+ LTHR

In my case this difference is significant at around threshold. Zone 4 going by % max (186) would be
165-173 bpm. However, uising % LTHR (167) I get 157-167 bpm.

Having said that, it does sound like a hard ride, averaging ~92% LTHR for ~5 hrs.

Yes, they are based on LTHR. Perhaps my combination usage was confusing. The numbers I'm using are off what you listed, but for those that aren't as familiar with Friel's methods, I guess I posted the ones I did. Probably dumb of me, since the folks I'd want info from are the ones that are familiar with Friel's zones. I should have used actual HR numbers, which are:

Zone 1: 111-141
Zone 2: 142-153
Zone 3: 154-162
Zone 4: 163-174
Zone 5(a, b, c): 175-188

My numbers aren't exactly the percentages, about 1 beat below because most of my zones I based off an original test of 172 LTHR. I've re-done LTHR tests (both the 2x20 and the 40k TT) and found it closer to 174-175, so I just bumped the top of zone 5. I have a two day 300k race this coming weekend, and after that I should re-adjust everything and see how the efforts change for time in zones.

VW