Puerto de San Isidro has little traffic (except in its low end), better views, and more kilometers of fun than the more crowded N-630 between Leon and Oviedo through Puerto de Pajares, so its a good alternative to it.
As an alternative to the main road between Burgos and Bilbao
you find this fantastic road. Curves start in Oña, and going
north between trees and mountains you find Puerto de Angulo
(it has a good view point). At the bottom of it you will find
Carretera de estar ocupado todo el tiempo, miles de curvas
de todo tipo y paisajes extraordinarios, pocas rectas
para apretar el mango. Velocidad media baja pero te hará
El Escorial - Robledo de Chavela (por la Cruz Verde) -
Valdemaqueda - Cebreros - El Tiemblo - Navaluenga.
Starting from San Vicente take the N634 before turning off onto the N621 to Unquera. Starts off a nice low level road with sweping bends & scenery before it starts to climb into the Picos de europa Mountains. A fantastci run along a mountain gorge with tight bend after tight bend before the road cal...
A really good selection of tight hairpins, fast sweepers and a nice view as the road rises up from sea level to around 1000m. As this is rural Spain, you may need to pay some attention to farm animals straying into the road (although I didn't see any on the way). This route is ideal if you've just g...