Hi: When I walked the Coastal Way in July, I was not looking at it from a biking perspective, but I do remember thinking that about 75% of it would have been on boardwalk, cobbles or pavement. The cobbles in Portugal might make for a bumpy ride, but it would be doable. There was one section, on the way into Baiona, where we stuck to the main road along the ocean, but there was a fairly wide bicycle/pedestrian path that made for a pleasant walk. When we got into Spain we repeatedly saw an extended family walking the route with two physically impaired members that were non-walkers. The non-walkers were in a one-wheeled device that could be pushed from the rear and pulled from the front. It was truly inspiring to see the love and caring within the family. If they could get up and down the trails, I believe you could do most of it on a bicycle.