That’s similar to my own experience.
Also, virtually every athlete I’ve met. It’s a very interesting issue. There’s many reasons for it.
- Cooling
- Climbing pedaling physics
- Bike movement
- Motivation
- Zero ambient C02 build up
The fascinating part, is this effect on your yearly training. Hypothetically, if every threshold or above session was done under optimal outdoor conditions, what are we talking, 100 sessions per year?
From my experience, I gain approx 10w. I’m a small 62kg rider. Larger riders sometimes gain more like 20w. Add this 10-20w stimulus over 100 training sessions. That’s a massive increase in load. One applied in all your key sessions. I cannot imagine it not having a substantial benefit, long term.
Obviously, you need the weather, the geography and time to train in this manner. Not many folk have that combo year round.
However, it’s definitely something to think about.
Certainly, when you get the chance to do your harder sessions outdoors, jump at it.