Dewy
member
Bindings hold the boot onto the ski. They are connected to the ski.
On downhill skis, the boot is held onto the ski at both the toe and heel end of the boot, and when you fall, you can give yourself a nasty injury (eg broken leg or horrible knee injury) because you are rigidly connected to the skis. To avoid this the bindings are set to release the boot from the ski when you fall.
If you set your bindings on a loose setting to ensure they release you when they should, they may sometimes release when you are skiing, but if you set them tight, there is a risk that they may not release when they should.
On cross country skis, the bindings are much simpler and only hold you in at the toe, so you don't need the quick release.
On downhill skis, the boot is held onto the ski at both the toe and heel end of the boot, and when you fall, you can give yourself a nasty injury (eg broken leg or horrible knee injury) because you are rigidly connected to the skis. To avoid this the bindings are set to release the boot from the ski when you fall.
If you set your bindings on a loose setting to ensure they release you when they should, they may sometimes release when you are skiing, but if you set them tight, there is a risk that they may not release when they should.
On cross country skis, the bindings are much simpler and only hold you in at the toe, so you don't need the quick release.
United States
