>I would not have thought that. Coming from a mountain and road biker who very often bikes above 20 mph, but very often bikes much slower than that as well.

Downhill skiing (as opposed to cross country skiing) is done going only downhill. So the speeds will tend to be higher than an average for cycling that includes flat and uphill regions.

I’m a casual skier, and I know I’ve hit 50 mph for short stretches. It’s very easy to pick up a lot of speed under the right circumstances. In contrast, when I cycle it’s on flat ground at a pace that evidently is slower than Google maps expects, so presumably quite a lot slower than my skiing speed.