It isn't capable. The only reason is that Garmin don't enable it in this watch as it's a lower end watch and cycling VO2Max is considered a higher end function. You would need a Fenix3, a 920XT or an Edge to get cycling VO2Max
CW
So I can expect the Forerunner (or Edge) won't be able to estimate power from HRM and cadence sensor?
you could try a CIQ data field such as https://apps.garmin.com/en-US/apps/2e20bb58-e8de-474e-b200-c78d6110060f
you are not however going to get a cycling VO2 Max even if the device supports it without a real PM