Fun bouncy run. The harder drop is about halfway down as the banks close in. Watch out for fences.
Takeout at the small bridge in Heolyrhedyn (just north of Ystradfellte) at the confluence with the Llia. To reach the putin head south up a steep hill and take a small road on the left upstream. Head up here for a few km and then park and walk down to the river.
Rainchasers is best experienced as an app.