Would help I guess if I gave you the route..
Cardiff-River Taff Trail to Merthyr Tydfil (Cycle path), Merthyr Tydfil to Brecon (Cycle path)
B4520 to Upper chapel, B4519 to Garth to Glandulas, B4358 to Newbridg-on-wye.
Cycle path LLwrthwl, Cycle Path to Rhayader NCN 8, Cycle path to Llanguric NCN 8
Cycle Path to Llanidoes NCN 8, Cycle Path to Staylittle NCN8, B4518 then B road NCN 8
B road to Machynlleth NCN 8, A487 the B 4044 the Minor Road NCN 8, To Corris NCN 8
To Dolgellau NCN 8, Barmouth NCN 8, A496 to Dyffryn Ardudwy
Then Minor roads NCN 8, To Harlech NCN 8, Penrhyndeudraeth NCN 8
Porthmadog NCN 8, A487 to Penmorfa NCN 8, Minor roads to Dafarn Faig NCN 8
Then disused Railway line to Caernarfon NCN 8