I've started doing some indoor cycling on a Watt Bike and I've noticed it doesn't seem to calculate a VO2 Max after my workout so I'm wondering if it's just that the watch doesn't calculate VO2 Max for indoor activities or if I'm not giving it long enough. I normally do 20 to 30 minutes cycling and I always connect my watch to the Watt Bike sensors as well as wearing a heart rate strap and I generally keep my average HR during the workout fairly high (in the aerobic or threshold zones) so I would have expected it to calculate the VO2 Max for me - with running I can do a short easy run and it will give me the VO2.