Hi
As far as I know there is no direct bus or train from Madrid to Roncesvalles. It is, however, easy to get from Madrid to Pamplona either by train (www.renfe.es) or bus (www.alsa.es).
Many people just take taxis or hitchhike from Pamplona to Roncesvalles but I did find one link from 'fiona' on another site for Pamplona to Roncesvalles as follows:
"After much google-ing I have found the official online timetable of the bus services between Pamplona and Roncesvalles: [
www.autocaresartieda.com] . I think it works with "pop-ups" as once you reach this page you then have to click on "linaes regulares" and then select the Jaurrieta-Pamplona service. Lots of services are listed; clicking on the details button at the far right edge gives the info about the days of the week that the service runs and the dates between which the details are or were valid. The site is only in Spanish and Euskara, but I found the Spanish version OK to follow. "
You have to follow her directions carefully but it does give a schedule. Please note that the above email was written in June 2008. Thanks to Ivan at [
www.caminodesantiago.me] for the above information.
Buen camino, Cecelia