I did this trip in August of 2022. I write this now on 1/2/23, four months after the trip but my memory of this great experience is just as fresh as ever.
The total trip took me 7 days (and a 8th day to return back to the Atlantic side). I picked up the trail in Peyrehorade and finished at St. Marie La Mer. I would second what the other reviewer stated that this is may not be a great choice for a first tour, as there are sections that are rather difficult, particularly on a fully loaded touring bike. Fortunately, there are a number of relatively flat sections which allow you to rest between climbs.
Additionally, the signage is inconsistent and only present at parts of the route. You definitely need a GPS to complete this trip. I used my Garmin Edge Touring bike computer with preloaded GPX file from this website and it worked very well. There were a couple of parts, notably just before Pau, that were under construction and closed but it was relatively easy to find my way around in these cases.
The scenery is varied throughout the route and really pretty. You get nice mountain views throughout and will see lots of wildlife and farm animals and lots of agriculture. The beginning does start off relatively flat, but does begin to ascend quite a bit, particularly in the region just before Mourenx, again before Capvern-Les-Bains in the Baronies region, and again once you get into the Pays Cathare in the Pyrenées Orientales (Eastern Pyrenées).
I did almost exclusively wild camping and there are plentiful locations to pitch a tent. The route fortunately passes by supermarkets where you can resupply. I brought water disinfection tablets (in French: pastilles, available at any pharmacy) to be able to refill my water bottles without a risk of getting sick. I also packed a water filter to drink water from streams. I had several days that were above 40 degrees C during the trip so being able to refill your bottle anywhere is an absolute must if attempting this during the summer. Much of the route is sparsely populated so there are long stretches where you won’t be able to easily resupply. Many rural villages do not have any stores so when you see one, be sure to stock up!
The route was overall of good quality. The rail trails were amazing and well restored, especially passing through the old railroad tunnels and one part where you pass on an old railbridge just before Foix. The only part of the route that was of really poor quality was between Lourdes and Tarbes. Luckily, I did not destroy my tires or get a flat here but I easily could have!
Les Grottes de Bétharram was an amazing cave system I visited which is right by the route. There are also many places to visit on this trip that are actually not directly on the route. St.-Bertrand-de-Comminges has an outstanding cathedral and is a medieval town just a few km off the route. Le Chateau de Mauvezin in the Baronies region is a well restored fortress reminiscent of Carcassonne. The climb to get to it is grueling but well worth it. Another highlight is visiting the Chateau de Queribus, a Cathare castle near Perpignan (also another epic 8% climb). I was surprised that the medieval city of Foix was not a part of the route even though you pass so close to it which is a must see location. If you just stick to the V81, you really do miss out on so much of what there is to see in this region.
It was so interesting to see how the Pyrenees change as you go from west to east. After St.-Bertrand-de-Comminges, east of Montréjeau, the landscape gets progressively more arid where the western Pyrenees are very lush and green. I loved the eastern Pyrenees and found the Pays Cathare and Roussillon regions to be the most breathtaking of all. I loved the section which had the Gorges de Galamus on it. I did the hike off of the Col du Linas to the Pic de Bugarach which had an amazing view.
Here is how I broke down the route:
Day 1: Peyrehorade -> just past Pau.
Day 2: Just past Pau -> just past Lourdes.
Day 3: Just past Lourdes -> Lac de Montréjeau.
Day 4 : Lac de Montréjeau -> Foix.
Day 5 : Foix -> near Esperanza.
Day 6 : Esperanza -> Somewhere near Chateau de Queribus.
Day 7 : Chateau de Queribus -> St. Marie La Mer.
Day 8 : Return home.
This route definitely deserves more visitors! As the previous reviewer had stated, I saw very few long distance cycle tourists on the route.
Thanks for the great website!