The theoretics of Zone 2 riding

I just did a 20 minute FTP-test (resulted in 295W) and was checking my power- and heart rate details on Apparently, my threshold heart rate was calculated as 176 bpm, resulting in below scheme following the Friel method:


Whilst I can relate to the upper zones, i’m having some trouble interpreting the zone 2 power and heart rates i.e. 56-75% of power and/or 81-89% of threshold heart rate. Nowadays, when I do an endurance ride and keep the average power around 190 (for average heart rate of 135-140), I feel tired afterwards.

If, let’s say, i should train in the upper half of zone 2, then my power constantly needs to be around 210-220 W (heart rate app. 155). I know I can hold this for 1.5 hour, but i also know this will be quite taxing on my body, let alone that I ride 5 hours in that zone. Even the lower range of this zone seems very high. In the end, it seems that it won’t feel like an endurance ride because of the too high pace.

Is this a matter of training? Should I be building up in the endurance zone: not only in time, but also in percentage of power output? Or is this something that i’ll get used too by just going by my power numbers?

1 Like

I believe if you click that link the Friel protocol is to do a 30-min solo time-trial effort and then use the last 20 minutes average HR to estimate your LTHR.


You cannot use a 20min test for LTHR. Too high. So either do as @bbarrera suggests, or if you have Training Peaks (or something similar), do you have a “max HR for 1 hour”? That number would be close.

1 Like

^ that works too, my LTHR from 30-min Friel protocol is 161bpm and my all-time HR for 60-min in TrainingPeaks is 161bpm. I did another 30-min Friel protocol this year and LTHR was 161bpm. My LTHR has been the same for 4 years.

And after getting LTHR using Friel 30-min solo TT protocol, I then tell TrainingPeaks to use LTHR with Coggan zones calculation to set my heart rate zones.

The Friel HR zone for aerobic endurance (81-89% LTHR) is too high for my zone2 work. The Coggan HR zone for aerobic endurance is just right as verified by talking test, breath test, and INSCYD.


Ok, so most probably there is an overestimation of LTHR because of the above-mentioned reasons, but if you look at power alone then I find the upper end of zone 2 (let’s say 70-75% of ftp) a very daunting figure for a multihour ride, one that I know I will have trouble with to sustain, although my facts and figures tell me otherwise.

So theoretically, if I choose to ride for 3 hours this weekend with an average of 215W (again ftp = 295W), I should be relatively fresh afterwards?

1 Like

With zone2 from 56% to 75%, I’d rather target 65% on long 3-6 hour training rides. Less than that I’ll go upper zone2.

Coggan HR zone2 on TrainingPeaks appears to be 69% to 83% of LTHR, which is much lower than Friel’s 81-89% LTHR. I’m using Coggan zone2 for the reasons stated above.

1 Like

It’s ok to work the edges of that “zone”. Do what’s best for your current fitness level. Nothing wrong with riding at the bottom end of that zone if that’s what allows you to push out to 3 hours or however long you want to go. Also, you can dance around that zone during a ride. 30 min high Z2, 1 hour low, 30 min high Z2, 1 hour low. There are infinite possibilities.

If you’ve ever heard Team USA coach Jim Miller talk, he’ll say something to the effect of: “Long Z2 is what makes you a warrior”. It’s being able to hold those wattages–that seem daunting to you now–for hours on end.

1 Like

No, not necessarily. At 295W, maybe try 190W first, but don’t be afraid to “move around” in the zone as @anthonylane says (especially outside, where you’ll likely have to). You could do it like he suggests, or let the terrain dictate it, as I do with the rolling hills where I live.

So do most riders who have under-developed endurance and tempo abilities, even with high FTP. Keep at it with a focus on increasing duration (as opposed to intensity) and it will improve.

Rather than thinking in terms of a zone, maybe just think it terms of a cap (power or HR). Always pressure on pedals (except when not safe to do so), and don’t go over the cap (even on hills). Try to come back with very little coasting or near coasting (Coggan Active Recovery zone or high Variability Index). You’ll have little surges/spikes of power (standing to get up to speed after stopping at a light, for example), but other than that, steady pressure. Come back with what you do.


I think I’m feeling similar to you, @TmDrssrt - I started a block of Z2 training 3 or 4 weeks ago, and set an informal HR cap based on MAF, but essentially its just Z2. I started training at the top of Z2 (75% FTP based on ramp test, or 79% of a realistic T60), and it was killing me at durations over 2 hours.

I have now backed off from 75% to about 67-70% (depending on FTP protocol) and its easier, but nowhere near easy. My legs are pretty fatigued, and a 4 hour ride at this (on the trainer) is daunting. At about 3 hours in, my HR starts to drift up (by about 10bpm at the end). I feel I have been seriously misled in terms of how hard extensive Z2 blocks are!!

It’s definitely not easy, even though the workouts don’t have big spikes so don’t look intimidating. However it’s still 2+ hours of nonstop pedaling if done as prescribed, something most of us don’t get in the real world. If I ride flats there’s still coasting and intersections so I don’t think you can get that type of prolonged nonstop effort outside, unless you’re climbing a super long steady climb which I don’t think most of us have access to anyway once we get into the 2+ hour range

2 Likes uses 98% of the highest HR you have held for 20m for LTHR or 100% of 1 hour whichever is higher. It’s just a suggestion because you might have been dehydrated or whatever. So you decide to update your zones or not. You can look at the HR duration chart for inspiration:

I agree that riding for long in Z2 is tough. There is no such thing as metabolic steady state really (tx Dr Seiler) :slight_smile:


If you work at it you can get close… on Saturday I had a 2 hour zone2 ride. Removing the 10 minutes of one-leg pedalling drills, there was only 114 seconds (less than 2 minutes) of coasting. That is ~ 1.7% coasting on a ~1.83 hour ride. That ride has about 45 minutes in the city, and so I often taking right turns at red lights in order to keep pedaling. A little bit of luck with green lights that day, so targeting less than 5% coasting might be more realistic if you truly get stopped at 2-minute red light or two.

98% or 95%? 98% seems high. 98% puts me almost 10bpm above reality.

With the way my area is I don’t dare try to nail intervals outside, feel like I’d get into an accident paying more attention to my wahoo than the road. If I’m just doing z2 outside I’ll just ride around z2 power but if I really want to nail intervals my behind just stays home.

Where is this in Intervals.ICU?

You get a notice on the ride timeline page if it looks like your threshold HR might have gone up:

This is also shown on the calendar. You can click the note to update your zones (or not).

98%. I started with 95% but found better results (my data and a couple of others) with 98%. But it is quite likely that it won’t work out for everyone.

1 Like

My understanding is that if you do a proper three hour endurance ride, you should definitely not be feeling fresh by the end of the third hour.

The accumulated fatigue will be that much greater in the latter part of that third hour than the first or even the second hour.

1 Like

That goes for any duration which is your limit/max. Summer 2019 I did a lot of Z2, started with 2hr rides and maxed out at (repeatable) 5hr sessions (and a single 6hr ride). Was always the same when increasing to a new duration, I really had to work the last ~20min.

Unfortunately, it was the 5hr Z2s that had the most impact on my fitness, much more noticeable than 3 or 4hr rides (which weren’t that much different from each other).

1 Like

So what if you do two z2 sessions in a day? 1,5h in the morning and 1,5h in the afternoon/evening (for example). If the “magic” happens in those last hour(s) is it stupid to split or does it still happen because you are not completely fresh for the second workout?

Do a long ride. My longest z2 this year was 5+ hours and I didn’t feel fatigue until 4.5 hours into it. Not too long after that I had a big bump in FTP. That same story has played out in previous years (with respect to 5+ hour rides, not all were z2).

1 Like