Stigenfossen (or Heggheimsfossen, Støylsfossen) is a big waterfall just north of Klakegg. When driving from Skei to Byrkjelo over road E39, you will see the waterfall at the east side of the valley. There is a fence where you can park the car.
I am not sure if this waterfall has a consistent flow. Probably after heavy rainfall or with warm weather when there is a lot of melted snow (early summer) you will see the Stigenfossen on its best.
When I drove by May 2015 the weather was very cold and the flow of the Stigenfossen was low. I am sure a month later the Stigenfossen is much more impressive.
July 2017 I visited the waterfall again and the volume of Stigenfossen was more impressive.