These skis are ideal in cold deep snow and breakable crust. They are not fast in temperatures around zero or above. Also, because of their width and no metal edges, they are not suitable on ice and hard packed downhill slopes. And please note that they are not jumping skis.
In olden days each ski maker used the wood found in their area. In Telemark. Ash, birch and pine was most frequently used. Next to elm skis, ash skis have always been considered the fastest. Good elm is very hard to find and the wood tends to move, twist or warp. Ash is much more stable and a lovely wood to work with.