The longer route off the Tende and onto the dramatic Via del Sale (VdS). The Via del Sale is a long, quite remote section of track through a karst limestone landscape. It's one of the most incredible mountain roads in Europe. The Refugio Don Barbera isn't too far from the Col Tende itself, a couple of hours ride on a good day.
The descent off the Via del Sale via the Pas du Tanarel / Monte Saccarello area is very rough for a couple of kms – rocky MTB terrain, though rideable with care on 650B 'Road Plus' type bikes – and it’s a long, arduous descent to La Brigue with some rolling terrain in the woods.
At the time of writing (July '21) there are roadworks in the Roya valley, related to the damage caused by Storm Alex.
Between Saint-Dalmas and Fontan you have a 6 km long portion (downhill, on gravel track and tarmac) where traffic is one direction at a time.
At night and on week-ends, traffic can pass every hour between h00 to h15 from Saint-Dalmas to Fontan, and between h30 to 0h45 in the other direction. On weekdays the road is closed for works and only one crossing at 12:00 downwards and 12:30 upwards is allowed from 07:00 to 17:00.
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After La Brigue is the big climb to the Fort de la Forca and the Col de Turini, using a new road for the TNR. It's a tunnelled, balcony road that change into a dirt road and onto the Circuit de l'Authion towards the top.
You can see the sea from the top if it’s a clear day. You can even smell the sea air sometimes... the coast isn't that far away now.
The Roya valley between the Col Tende and the start of the climb to the Fort de la Forca is another potential supplies desert if you arrive there late. Restaurants are the main options though there is a Spar shop in Tende itself if you back-tack up the valley on this route. Worth studying the options on the map perhaps.