Today, I have driven from Holyhead to Swansea, right down the length of Wales. Mostly the roads are single carriageway, no wider than urban streets. Many are bounded by stone walls and have no 'escape' room at all. I saw about 15 cyclists during my journey. Because most traffic is doing 60 mph and the bikes are doing about 15 mph, the disparate speeds cause severe risks for the cyclists. Many of these roads have been modernised in the past 10 years and it is blatantly obvious that no thought at all was given to cyclists.
Frankly, it would be safer for the cyclists to ride on the right hand side of the road and face oncoming traffic, as is recommended for walkers.