I’d scoped this route out on my bike. It seemed to me it would be possible to climb to the Col des Mouilles in the French Belledonne mountains then take a really quick descent on foot back to the starting point.
The first 3k of the climb rise 200 meters in a series of hairpins. In the woods it is not too hot but it is quite steep. Things ease up afterwards with a further 200 meters climbing over 5 km to the col. It was pretty hard on the last section but largely due to heat then the gradient. From the col you descend North through the woods back to the road you climb up on then on a nice path to the pumping station where the parking is. Just 2.5km so a very good climb/descent ratio. Route finding on the top section is not straightforward with a bit of bushwhacking in an open forest.
The road surface is not bad and traffic is very light. Today was very hot, average of 28 C but 30C at the col (36C on the south side!) Hotter than in the valley! The route is largely in the shade but the segment from la Boutiere to the Col was hard in the middle section - full sun and 10% ramps.
