Local knowledge is more important for interesting mountain bike routes than for road bike routes. And the internet is full of useful little local web sites detailing this knowledge. This brilliant mountain bike loop has been used as a local “rando” for three decades: “Les Balcons du Lac.” See here for the official site.
The highlight is climbing Montagne de la Biolle and riding along the top ridge with occasional stunning views of Lac du Bourget – the deepest and largest (although only in summer) lake entirely in France. This 3D video illustrates the brilliance of the ride.
Starting in the village of Biolle, it’s not just the high parts of this route that are fun. The entire loop is full of local knowledge linking unpaved farm roads and very rideable trails while almost completely avoiding paved roads. Fantastic throughout.
There are a few stretches where I carried my bike, both going up and down. But the entire route is surprisingly rideable, even high along the forested rocky mountain ridge.
At Col de la Chambotte (see map) the route heads up to the Belvédère and the first lake views.
See here for a superb 4-col road bike loop that includes Col de la Chambotte as well as a gorge traverse.
There is a good 10 kilometres along the mountain, descending part way down the lake side.
Descending the lake side of Montagne de la Biolle:
Lac du Bourget is less well known by cyclo-tourists than its smaller neighbour Lake Annecy. But the cycling here is equally good. See here for a post detailing several rides in the region including both sides of Mont du Chat.
Local knowledge takes over again as the route cleverly avoids civilisation and loops through the forest around the south side of the mountain, finally taking some fun farm roads back to the start. I loved this loop. Challenging, fantastic views, and full of great trails linked together by a local expert.