Behind a gentle mountain saddle near Brixen im Thale it reaches the ski resort of Kitzbühel, which is also the district capital and lies on the federal road (Bundesstraße) to Salzburg.
Two peaks almost reach 2,000 metres in height: the Hohe Salve (1,828 m, also called "the Rigi of the Tyrol"), visible from a long way off, and the Gampenkogel (1,957 m).
Other large villages are not found until the upper reaches because, there, the valley floor is wider (see picture): Brixen im Thale (794 m), where several headstreams unite, and especially Kirchberg in Tirol (837 m), where the Spertental joins the Brixental not far from Kitzbühel.
In its lower reaches - between Westendorf and Hopfgarten - the Ache flows through a narrow gorge, through which only the Bundesstraße snakes - the railway line branches away in the so-called Windau bend.
Its larger side valleys are (listed from Wörgl upstream): The catchment area of the Brixentaler Ache covers about a third of the district of Kitzbühel, most of which is due to the Windauer and Kelchsauer Ache tributaries.