The Vario-Geo Concept for Rondoforks:
The ‚lo‘ position of the axle (resulting in higher stack, slacker angles, etc) is the optimum setup for going fast in rough, technical terrain or long distance endurance riding and touring on flat gravel roads.

The ‚hi‘ axle position (that puts you in a more aero position and gives the bike a steeper head angle) is appropriate for going fast on smooth tarmac or fast, flat gravel roads.