A large part of the first half of the 200k is on a segregated and well-surfaced cycleway. Traffic on the "A" roads is never a problem, the busiest sections are probably briefly through Conwy and Bangor and then the road between Criccieth and Penrhyndeudraeth and the short stretch on the A5 at Betws Y Coed but none of these provides anything unpleasant. As far as the extra sections of the 300k are concerned, I have never pedalled the old A5 across Anglesey but it's bypassed, so must be quiet and the A470 between Dolgellau and Trawsfynydd is not busy but expect some high speeds. However, the road is wide and as with most A roads in Wales, in good condition. All in all these are great rides, on good roads and well worth the effort, especially as they're in Wales, where sunshine is guaranteed.