To get to Roncesvalles from Madrid on the bus, take the bus from the Avenida de Americas bus station to Pamplona and then get the bus from Pamplona. The website movelia.es will help you with timetables. There's lots of information here on the bus from Pamplona to Roncesvalles -- I haven't paid too much attention, but I think there's been a bus added to the daily 6 p.m. trip. Hope this helps. Laurie
2002 CF: 2004 from Paris: 2006 VF: 2007 CF: 2009 Aragones, Ingles, Finisterre: 2011 X 2 on CF: 2013 'Caracoles': 2014 CF and Ingles 'Caracoles":2015 Logrono-Burgos (Hospitalero San Anton): 2016 La Douay to Aosta/San Gimignano to Rome:
Madrid doesn't have a central bus station as such. Barajas is an enormous airport but if you follow the signs - down the many escalators - to the Metro you will be able to get a fast trip into town to Estación de Avenida de América where the Alsa and Continental Auto buses leave from for Pamplona. Take a bus from there to Pamplona - about a 5 hour journey.
In Pamplona you then take another bus to Roncesvalles.
just went online and printed a great map of the Metro. I can see clearly how to get from airport, to hotel, to bus station. looking forward to the journey. thanks to those of you who helped with details. great help.