Normal? What to do?

[OakLeaf]

It doesn't make sense that your conditioning would have anything to do with it if you're already doing workouts that are more aerobic than cycling at a moderate pace.

The one thing that occurs to me is that your workouts are indoors. What's the weather like where you are? Is it possible you have asthma triggered by cold, humidity, pollen, car exhaust?

Fainting isn't good, and especially not on two wheels in traffic. Maybe get it checked out with your doctor?

[Wahine]

While Crossfit is intense, it's not really the same kind of aerobic work required on a bike. So it might just be a getting back into it thing.

However, I have to say that something doesn't seem right here and I would have to agree with Oak, you should talk to your doc about it. In fact, if you were a client of mine, I would insist on it.

[zoom-zoom]

Could you be dealing with vertigo or inner-ear issues?