# How to apply Stryd’s Critical Power to 80/20 Zones?

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• #10258

So I just got my Stryd and want to make sure I can use it right away for my 80/20 power based training. Stryd allows you to set your own Critical Power by using a recent 5k time (as an alternative to their auto calculated CP, which requires at least 3 runs for a first estimate). So I used my 5k time from last Tuesday’s time trial (the one we also used for setting HR and Pace zones) and let Stryd determine my CP based on that. According to them my CP is 268w. Now, is it fair for me to use that value and put it straight into the zone calculator/TP? My understanding is, that I only need to multiply by .95 if CP was auto-calculated by Stryd. Am I missing something or does my approach and these power zones make sense?

Here’s a screen grab of my power zones in TP.

#10402
David Warden
Keymaster

Christoph,

Unfortunately, Stryd does not yet define what “Critical Power” means. There is no industry standard on “critical power.” Could be CP30, CP20, CP60…

For now, athletes who take 95% of the auto-calculate CP value get close to threshold pace. However, a more accurate test is still going to be 95% of an actual 20-minute TT.

David

#10404
MartinH
Participant

I got a Stryd for Xmas and am still learning how to ‘drive’ it 🙂

From the FB group, their ‘definition’ of CP is that it’s CP somewhere between 30 and 70 minutes – depending on the athlete.

Steve Palladino who seems to be the group’s go-to guy for power-based plans reckons it’s only elite athletes at the longer durations, and most Stryders at the lower end.

As it’s that variable, I would say certainly as David suggests, 95% of an actual TT is the best plan.

I ran a flat out 10k a few weeks ago, so at least on that occasion, my HR,Pace and Power all tied up , so I’ve based mine on the 30 min peak according to Training Peaks for that run.

I think it’s going to be ok – but the last couple of weeks here have been cold, and frosty or snowy, so currently I’m finding that despite executing the workouts ok on power, I’m spending a lot of time in zone x / low Z3 for HR. I’m hoping that it will sort itself out when conditions improve (even though it was cold for the 10K, it wasn’t this cold and I wasn’t struggling for traction in places)

#10412

Thanks, Martin. I appreciate your input. I will just do a 30min TT and go with the 95% of estimated CP for my zones in TP. Sounds like that has worked for you and that’s also what David advised to do. So far loving the responsiveness of power-meter running. But Stryd’s Apple Watch app is unusable at this moment. No support for audio cues… makes it completely useless for me.

Good luck with the weather! Temperature definitely has an effect on HR, and that’s another reason why it’s better to run based on power and not on HR.

Happy running!

#15143
Participant

Hi – I am also a new Stryd user. I have manually set my CP in Stryd using the 8020 rFTP figure (from a 20 min TT), but the 5 Stryd zones now calculated from the new CP/rFTP in no way match the 8020 zones. Should I manually edit the zones in the Stryd app, and if so how should I map the 7 8020 zones to the 5 in Stryd.

Matthew

#15145
David Warden
Keymaster

Dad, see the Q&A from our document Understanding Your TrainingPeaks Structured Workout Plan

Q: My Stryd zones and 80/20 Zones are not aligning in the Stryd app. Why?

While 80/20 uses a fixed duration to determine run power threshold – 95% of a 20-minute trial, or 95% of CP20 – Stryd uses a dynamic method to determine critical power. This could be CP20 for one athlete, or CP40 for another. Therefore, the two methods may not completely align as the Stryd method is fluid. To resolve this, disable Auto-Calculated CP in the Stryd mobile app and manually set your Stryd CP to match your 80/20 run power threshold.

If the run power threshold set in TrainingPeaks is the same as the critical power manually set in the Stryd app, the two applications will align.

David

#15146
Participant

Yes I have read all the linked articles and followed the instructions in them. I have disabled the Auto-Calculated CP in Stryd and manually set the CP to match the 8020 run power threshold. What is different is that the 5 zones in the Stryd app do not match the 7 zones in the 8020 system. Is there a way to reconcile them? I can manually change each of the 5 zones in the Stryd app, but how do they map to the 7 zones in the 8020 plan.

#15148
David Warden
Keymaster

No, we don’t provide a way to map the 5-zone Stryd system to the 7-zone 80/20 system, because it is not necessary if you disable auto CP and manually enter your FTP. Then, TP pushes your custom 80/20 7-zone system (or 3-zone, or 10-zone system, whatever you have setup in TP) and bypasses the Stryd 5-zone system. When you choose the 80/20 system, you abandon the proprietary Stryd, Garmin, Polar, Coros or TrainingPeaks zone systems.

Think of 80/20 as the Metric system and Stryd as Imperial. Both are equally valid to measure distance, but you should commit to one or the other when building a rocket. Having one foot in each system could cause the rocket to crash.

David

#15503
Participant

Hi, I got a Stryd a few weeks ago. The documentation (or lack of) is appalling, but Stryd support pointed me at the Garmin Stryd Workout App (https://apps.garmin.com/en-US/apps/1df63e9d-f886-4541-b188-2406a3bf5be0). If you have a Garmin watch this allows you to sync the 8020 structured workouts in Training Peaks and run using the 8020 Power zones. I prefer it to the 8020 Garmin data field.

• This reply was modified 2 years, 2 months ago by FatDad.
#16057
Newdent
Participant

Another new stryd user here.

The auto-calculated CP from my run today was 187W and this is basically the power I ran at for my top of Z2 endurance run and if I’ve understood correctly, matches my talk test heartrate.

Can I get from this power value to my rFTP? I’ve played about with values in the running power calculator and a FTP of 212W gives a value of 187W at the top of Z2. Would you say that in this instance I can use 212W as my FTP?

It would be very convenient if this relationship was linear as it would mean you could get to FTP using a talk test.

#16067
David Warden
Keymaster

Newdent, any use of the auto-calculated CP automatically disqualifies that value in the 80/20 zone system. Remember, the auto-calculate in Stryd is dynamic. It could be CP20, CP30, CP60… it’s an unknown. It’s not a bad method, it’s just not compatible with 80/20 as we need a fixed value to determine zones.

So, no, I can’t take your auto-calculated value and convert it in any way. I can use the other 3 options in our documentation (20-minute TT, plateau test, or talk test). Those are all static, consistent tests.

We currently recommend you turn auto-calculate CP off in Stryd and manually put in your known field test results.

If Stryd would share what CP value they used, I can work with that. If the auto-calculate came back with “200 watts based off of a CP30” I can convert that for you. But, because we don’t know that the CP value is, I can’t use it.

David

#16070
Newdent
Participant

Thanks for the reply David. I read on a separate post that as a rule, you’re unable to use auto calculated CP but how about in my situation, where I have a power value that corresponds to my talk test heart rate? Can I use the power calculator to get to FTP by entering values into FTP until the power value at the top of Z2 matches my talk test value?

Thank you

#16071
Newdent
Participant

I’m such an idiot, I’ve just realised that talk test is an option in the power calculator. Perfect!

#16078
Participant

If you do a 20 min simultaneous test (as described on the same page as the other tests) then you can get HR, Power and Pace zones all from one test. Even if using only Power this may help as, for example, my Power has not gone up much but my Pace has due to my getting more efficient at running. If I was only looking at Power figures then I might be less encouraged.

#16089
David Warden
Keymaster

Newdent, not an idiot! This is complicated stuff. So many options! I’m really grateful you’re posting here and hope you’ll continue, as it helps hundreds of athletes.

David

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