It is absolutely risky. Easily black out. EDIT:: added my experience I was riding mountain bike, and went to competition here and there. And then I stopped fo

It is absolutely risky. Easily black out. EDIT:: added my experience I was riding mountain bike, and went to competition here and there. And then I stopped for many months, got back and rode the same speed. For real I thought I was going to die, it was almost a black out and panic. Never again risking with "coming back with intensive training" .. just no.