Downhill skiing. I would say that I’m still a better skier than mountain biker… maybe it’s because the cost of a mistake when mountain biking is far greater than when skiing. I love deep powder and back bowls, but we don’t get much of that here on the east coast. I wouldn’t think twice about skiing a double black diamond. I think if I did a real double black mountain bike trail I’d have to walk a few sections.
My sister and brother in law got me in to mountain biking, since there is a lot of overlap with skiing and mountain biking they thought it would make sense. It is quite common for a lot of the winter sports enthusiasts to hit the trails on their bike during the summer months.