There is a cycle path that starts to the south of Chambéry and continues along the Lesse river to the Lac du Bourget finishing at the port of Aix les Bains. About 20km one way. I decided to explore this path from just outside of Chambéry to the north on a fantastic autumn day. Sunny but not too hot at 10 am.
The main problem with the path is a 5km section that is concrete to the north of Chambéry where pole points, even super hard carbide roller ski tips, won't bite. The route is generally flat. There are a couple of wooden bridges to cross. These were a bit damp and slippy early on and the gaps in the wooden slats can break rollerski poles. There are a couple of gentle and very short downhills before reaching the Technolac campus. Here you have to be careful to avoid students and just after the campus there are two underpasses with gratings to catch rain water, a quick jump will get you nicely over these but there is a shortcut via a bridge over the Lesse which avoids these.
You then traverse across the southern end of the Lac du Bourget. On a cyclepath but beside a busy main road and under the airport flight path. Just light planes in the autumn. Reaching the end of this road there is another pole eating footbridge then a choice of traversing a parking lot or continuing on the cycle path which climbs a hump back with further bridges. You now join the lake path proper with fantastic views of the Dent du Chat and lake. After 5km of superb rollerskiing you traverse around the Lido, take a bit of road to arrive at the Petit Port and you can continue along a wide promenade to the Grand Port of Aix les Bains. Here you can stop for a drink beside the lake before returning via the same route.
The most interesting section is the cycle path by the lake. Arrive early as this gets busy in the afternoon with walkers and cycles and dogs! It is very scenic and often used in advertising of both rollerskis and cars, including are a couple of photos from Decathlon.