Tronåsen on a BMW R1200 GS Adventure

The road over Tronåsen was built between 1840 - 1844 as a part of the main Western route. This was the first purpose built road for horse carriages between Oslo and Stavanger. Prior to this, there had only been a horse track. Bakke bridge, built in 1844, was designated as a National historic monument in 1959 and the remainder of the road in 2009. The road over Tronåsen is about 5 km long. Along this stretch there are eleven 180 degree curves or 'switch backs' : Eight on the western side, and three on the eastern side. The eastern side of the hill is steepest with a gradient of 1:4. The road is 2.5 - 3.5 m wide.