The Globe and Mail just picked Slovenia as one of the top Adventure Travel destinations for 2011. So, why not make it a biking trip? Check out this tour by Sacred Rides:
ALPS AND ADRIATIC: Croatia + Slovenia
Discover two of Europe’s hottest new destinations: Croatia and Slovenia. Old World charm meets new world adventure as you spend 9 incredible days exploring the world of the Balkans: spectacular snowcapped peaks in the Slovenia Alps, underground mountain biking in a 400-year-old mine, sailing on the Adriatic, wine tasting in Istria, and plenty of amazing mountain biking.
More info here