It is a better track than Afon Arban though a climb either direction and some unrideable bits on top. Possible but not easy.
(Afon Arban going E is at least downhill)
I have never done the (multiple) climb approach from off the Tywi track though.
When I’m out that way looking for a route I usually go over Foel Drygarn and down Nant Paradwys.
At present I`m thinking of doing Llyn Brianne dam to Llangurig via Abergwesyn, Bwlch y Ddau Faen, Nant Paradwys, Elan, Rhayader. Things may change.
Been up Plynlimon then, Pistonbroke?