What route did you use for Barcelona to Valencia? Main roads or backways? I ride in the surroundings of Barcelona very often, but the way out towards the south is almost impossible. All freeways trapped between hills and mountains.
We came into Barcelona on the C245. We had to use the bridge to get across the river. There is a scenic highway that hugs the coast just south of the city, and secondary roads also going south along the coast.
With the right gear, you'll be fine even below 0 C if not raining/sleeting. Even that's doable but miserable.
Having the right gear is everything. Also, having a wife who enjoys the same things I do helps
However, we were a little younger and tougher when the bottom picture was taken.
Our new winter tent
Sorry, a little OT, but I couldn't resist. My excuse is that we have not had any good skiing until last week, and I'm getting cabin fever.