I edited it in a way so you don't see my 25 year old ugly red Ortliebs, so you can imagine i was riding with $2000 boutique bags strapped all over my bike :)
I did the trip last September. It's mostly on asphalt, but i do absolutely love the calm small asphalt roads in France. I love gravel too, but being able to just look around and not just in front of you looking out for potholes and bumps, having a silent ride is really just as nice i think. On the small roads towards the end i hardly encountered cars ever, it was almost strange. Just the post woman.
It starts in Interlaken, and i take the cable car from Gsteig up to Sanetschsee. Sanetsch is not ridable from the north, maybe it is hike-a-bikable but from what i saw it will be a really tough hike or climb i think 800m up too.
The route follows a lot of the 'Route des grandes Alpes'.
Personal highlight was the Galibier, i had camped about 1000m below the pass and started going up real early, hardly anybody on the road, just the marmots and me on this beautiful morning. Was incredible. You can hear the marmots briefly in the clip.
This is the route if you're interested.
Interlaken - Gsteig (cable car to Sanetschsee) - Sanetschpass - Col de la Forclaz / des Montets - Col de Saisies - Cormet d'Arêche - Col de la Madeleine - Col du Télégraph - Col du Galibier - Col de l'Izoard - Col (tunnel) du Parpaillon - Col de la Cayolle - Gorges de Daluis - Gorges du Cians - Col de la Couillole - bunch of small cols in Provence - Nice