To be really honest, there are more beautiful parts of Wales. If I were you I would ride up over the Beacons and then via Rhayader > Elan Valley > take the Aberystwyth road at the top of the Elan Valley. That would really be the most stunning ride - the loop around the Elan Valley is one of my favourite routes anywhere in the world.
I know you're a really strong rider, but I've ridden extensively in Wales (my Mum has a house there and half my family is from there) - it is really tough. 100k there is like a very hard 170k in Surrey/Kent.
To be really honest, there are more beautiful parts of Wales. If I were you I would ride up over the Beacons and then via Rhayader > Elan Valley > take the Aberystwyth road at the top of the Elan Valley. That would really be the most stunning ride - the loop around the Elan Valley is one of my favourite routes anywhere in the world.
I know you're a really strong rider, but I've ridden extensively in Wales (my Mum has a house there and half my family is from there) - it is really tough. 100k there is like a very hard 170k in Surrey/Kent.