Thank you, guys!
Rojo is right, this was filmed using the awesome Insta360 One X. I firmly believe 360 is the future of action cameras. With the invisible selfie stick you can do even more spectacular shots, although it would look weird mounted on a bike. Check this out:
With a 360 camera, you don't worry about pointing it anywhere in particular. You can do all the panning and zooming on the computer (or phone) after the ride.
Another benefit of 360 cameras is the amazing image stabilization. Because the camera sees everywhere, it can stabilize any shot without cropping. You can actually throw the camera up in the air, letting it spin uncontrollably, and still get perfectly stable video!
I'm not using any gimbal, the camera is simply mounted to a GorillaPod on the handlebar, as you can see 8 seconds into the video. It looks flimsy, but it stayed solid for the entire 19 hours.
Yes, traffic was never an issue. Norway is thinly populated to begin with, and much of this ride was through rather remote areas. The ride was last Saturday, but it was the day after the Norwegian Constitution Day, with plenty celebrations, and that may have had an effect too.