From Le Bourg-D'Oisans take the D211 to L'Alpe D'Huez, this road is 14kms long, has 21 hairpin bends and rises 1100 metres up the side of a mountain. As it's a special section of the Tour de France the road surface is kept in tip top condition. If you can take your eyes off the road for long enough the views are pretty spectacular.