Source
r/cycling•
EhGoForIt

What power zone calculator?

I just started my first structured training using an 8020 Endurance plan. I have taken 2 FTP tests that put me at about 230 (and both within measurement error). I used the 8020 Endurance calculator (https://www.8020endurance.com/8020-zone-calculator/) and my zones are fairly high based on perceived effort and my heart rate. My Zone 2 is 161-191, and being right in the middle makes my HR like 170s - pretty hard!

When I use other calculators like British Cycling I get a radically different Zone 2 at 128-177. The center for that is a whole 20 watts different!

So...what power zone calculator do y'all use and why?

Posted Feb 10, 2022, 3:45 AM UTC

513
OhOkOoof•

How long have you been riding with power? Once a couple weeks of rides pass with hard efforts, you should upload your data into intervals.icu (free with Strava integration). It will calculate your HR and power zones from there. I’ve had them professionally measured via metabolism and they were very close to the intervals.icu predictions. Highly recommend

5
lotr_office•

I definitely second the intervals.icu recommendation. Lots of great tools and a good way to know how hard you can train.

2
[deleted]•

One caveat being that the model needs a max effort, and people with strong anaerobic contributions probably need to set the minimum interval length higher. If he's used a ramp test to determine FTP, intervals.icu eFTP will be within a few %.

2
EhGoForItOP•

This is awesome! Thank you!

2
[deleted]•

Zone 2 should be 50-75% FTP, not whatever that is. So 130-170ish (mental math). Without knowing your max HR/LTHR it's impossible to say, but 170bpm sounds awfully high for a Z2 effort.

2
SharkyFins•

Totally agree about the heart rate aspect. My max is heart rate is 206 and my zone 2 HR tops out around 160 under normal training load

1
janky_koala•

If this is an 8020 plan wouldn’t it be using a three zone model?

1
[deleted]•

Maybe? If so, they should do some rebranding.. it’s pretty well accepted at this point that when we’re talking power zones, we’re talking about something derived from Coggan’s work.

Edit: and no. Looked at his link, and they have a very janky looking 7 zone model.

2
janky_koala•

Yeah I checked that too. OP has botched it though, as the result doesn’t match the FTP they stated and your maths is right.

3 zones is coming more common with the raise in popularity of polarised training, hence me questioning it.

1
MoonPlanet1•

FTP tests vary - if you're relatively good at anaerobic stuff, a 20' test will overestimate your FTP slightly, and a shorter test (e.g. ramp) will overestimate it by even more. The textbook Z2 (in the textbook 5-7 zone model) upper-bound is 75%. I think what the 80-20 website is looking at is slightly different - they put threshold at the top of Z3 whereas most schemes put it at the top of Z4.

Ultimately ride by feel - Z2 should be an easy, all-day pace. Don't slave away at 74% of FTP just because a calculator says you "can".

2
Cyclist_123•

These are the zones that most people refer to https://www.trainingpeaks.com/blog/power-training-levels/

1
janky_koala•

There’s multiple different zone definitions used by different plans. Are you looking at a 3 zone or 6 zone model?

1
Madrugada_Eterna•

I use the British Cycling calculator. That gives more sensible power zones than the calculator you linked to.

1