There is gold in them hills….
One of the best rides in snowdonia is along the north Wales path from Conwy to Aber falls (don ride down the road, ride the FP to the west) Then onto the beach to llan fairfechfechan, up onto the national cycle path then up synchnant pass and down Conwy mountain for a very fast win.
Eluded to above by @breninbeerner
Or….
Llyn cowlyd – instead of going down the road, go over the dam, but of hike a bike over the ridge and take the path down in to Llyn crafnant.
You can ride over to Llyn geironnydd And take miners path to Trefriw.