No Vo2Max value after 40+ days of use

Alex0007 said:

I'm doing cycling activities without powermeter.

With the 265, you need a power meter to get a cycling VO2 Max.

"This feature requires a power meter and wrist-based heart rate or a compatible chest heart rate monitor. The power meter must be paired with your watch (Pairing Your Wireless Sensors)."

https://www8.garmin.com/manuals/webhelp/GUID-F41EAFB3-6CC9-42DE-9C6C-9E358DBB0671/EN-US/GUID-3E971364-A756-4057-B22D-C41250B2A82B.html

See also:

https://support.garmin.com/en-US/?faq=lWqSVlq3w76z5WoihLy5f8

I'm talking about general vo2max, not cycling vo2max

Funny, could you provide a link where this information comes from?

The screenshot doesn't make it clear, and I can't find such information through Google.

support.garmin.com/.../

Thanks, it seems that this is not about forerunner. You need to work hard with him, with extras enabled sensor or GPS or power meter. Here  @Etupes25 answer is accurate, about what actually works.

Why Instinct 2 Solar was able to set value then? What difference it have in specs that allowed vo2max to be filled from there?

Alex0007 said:

Why Instinct 2 Solar was able to set value then?

To be honest, I don’t understand how you can estimate VO2Max simply by measuring your heart rate without knowing what kind of load your body is experiencing.

Conditionally - if I just lie down for a month, walk, eat, drive a car, lift the tablet as much as possible, but freak out, wave my arms and my heart rate changes because of this - will I get the correct VO2Max estimate?

Of course I believe in the power of science, but in my opinion it’s not serious.

If we are talking about some kind of average monthly load model, then the accuracy of the assessment based on it is not clear to me.

Cycling power can be estimated with sufficient accuracy (10% error). But Garmin not doing it. Also it ignores power calculated by side-loaded data fields. 

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All I'm asking: why Instinct 2 Solar was able to provide vo2max value and Forerunner 265 can't (under same usage patterns). Where can I see this functionality difference in specs of both watches? 

Alex0007 said:

I'm talking about general vo2max, not cycling vo2max

Did I understand correctly that this topic is clear and closed?

As for the rest.

The difference in specifications is easy to view on the website, compare option.

The functional difference is a vague formulation. 265 measures vo2max(running) vo2max(cycling) as stated in the specification, details in the manual.

On the chart you posted in your OP, there is a VO2 Max value for May. What watch was this?