Originally Posted by tuz

You could calculate the precise change in length (and consequent HT angle change) but you'd need to know the original fork length & rake, as well as the radius and location of the bend. I made a rough calculation using triangles and, for 20mm of rake increase you'd loose about 10 mm of fork length (and tire clearance or brake reach). This document by Matchak tends to agree. By loosing 10mm the HT/ST angles would increase by approx 0.6 degrees, and the BB would drop 5 mm.