I also agree: the trail between Lake Palü and Cavaglia is much more difficult than the 3 out of 6 technical points given here. Rather 4-5. Otherwise tip top.

Tour done on 17.08.25.
But I pedaled from Poschiavo itself to the Bernina Pass. Very beautiful and easy to pedal ascent.
The scenery is an absolute highlight and the trail is just awesome (official route 673).
Simply brilliant :)

Relatively soon after the Cavaglia gorge, you can turn left onto the "Ciak si gira" trail. It is well signposted. It has short S4-S5 sections that you can push (mine) and is otherwise a very successful, racy alternative to the marked route.
Highly recommended for very good riders.

I rode the tour last Tuesday - clearly my personal highlight of 2 weeks of summer vacation in the Engadin! Many thanks to everyone involved...

I can only confirm the aspects mentioned in the previous comments:
During the high season, you can expect a lot of (oncoming) traffic, especially in the section from Diavolezza to Bernina-Ospizio.
The section after Lagh da Palü is largely impassable => take route 673 here

Detail by the way: according to my Garmin, there were about 150 meters more uphill than indicated in the tour description

I rode the tour twice last fall. Simply amazing, great panorama & fantastic scenery. It's best to get off at the Bernina Pass on the way back and ride back towards St. Moritz

If you still have energy, you should definitely do the same tour from Bernina back to Pontresina, easy but very flowing trail

In my commentary from September 26, 2019, I described my ride from Pontresina over the Bernina Pass to Poschiavo and also included the link to that tour video: https://youtu.be/Pb-j2hBAbw8

Now I was back on the Bernina Pass and rode in the opposite direction to Pontresina with a detour to the Morteratsch Glacier. A fairly easy tour but with a great nature experience in this glacier world. My video is on: https://youtu.be/SaUq_ekoGrE

Great tour. We rode this on 10.09.2023. Based on the many comments (thank you!), we skipped the detour to Lagh da Palü and followed the official red bike trail signs. This is by no means boring - i.e. nothing like the smooth flow trail / hiking trail we were afraid of - but it's consistently moderately challenging and therefore enjoyable to ride. To our taste, the variant via Alp Grüm (in the aforementioned less demanding version) is more beautiful than via La Roesa, which we also rode.

Cool Day . https://youtu.be/exRuVvY7aVw?si=Nl9lOfek5HJxh0DU

Very nice tour, I left out the detour to Lagh da Palü due to the previous comments. The rest was in very good condition in August 2023.

Beautiful tour. Side trip to Lagh da Palü omitted due to the hike the day before. Respect to those who can ride the stretch directly after the lake. From Pontresina to Lago Bianco (and in the opposite direction) everything on 2 wheels is on the road (& hikers). It's worth taking the off-peak times in the main holiday season! At the Corviglia glacier garden, a look into the gorge/short visit is recommended.

We rode the tour today! Top class! I highly recommend the Ristorante al Crott, just behind the train station in Poschiavo! As for the tour, I would recommend everyone (not named Camille Balanche) to stay on the signposted bike trail after Alp Grün and not ride down to Lagh da Palü as suggested here. It says crisp single trail. That's a gross understatement and definitely not 3rd level riding technique for 30-50% of the route. Don't know who rides this at all except Camille 😉. Otherwise great and definitely 5 stars!

Something of the most beautiful that connects the Upper Engadine with Poschiavo !!! : https://youtu.be/uvQAE326Khs

Rode the tour on 10.09.2022. Very nice tour. I would also classify the trail between Lake Palü and Cavaglia as S4. Steps with coarse stones. Rest of the descent easy to ride. Highly recommended.

Top tour
Especially the part from Lac Palü down to Cavaglia is brilliant. More of a 4* descent than 3*... but highly recommended.

The route is great - the variants that deviate from the 637 are highly recommended.

I rode the tour on July 16, 2022. For riders with heavy enduro bikes like me, I recommend the train to Bernina Pass. Very cool route with beautiful views. Don't forget to eat pizzoccheri in Poschiavo! Attention: the last post bus back to the pass rides at 8.05 pm. From the Bernina Pass it's a flowing descent into the valley. I really like this tour.

I did this tour on 02.07. Very nice trails are fun. Will do the tour again. I rode everything from Samedan 76km 2300hm.

Wonderful tour with great views and lots of single trails. I wouldn't recommend the "detour" via Lagh da Palü, the path below the lake is extremely rocky, I don't know if anyone can ride it at all, but we walked a large part of it. Perhaps the heavy rainfall in recent weeks/months has made it even worse. Down at Cavaglia, part of the trail has been completely washed away by the river. So I would definitely just follow route 637 next time, and there will definitely be a next time! :)

Great fun and fast descent to Poschiavo. The route past Lagh da Palü to Cavaglia is technically very demanding and only recommended for technically experienced bikers. We enjoyed this section of the route.

We rode the tour today. It was actually a great tour that we were really looking forward to. Today I realized for the first time that the classification of a tour is not correct. Because the part down after Alp Grüm where you leave the official route, past Lagh da Palü down to Cavaglia, is not a riding technique 3 trail. It is very rough, very stony and very steep. We recommend following the official route 637 at the top.

I got lost on the way from Alp Grüm to Poschiavo. After the Cavaglia train station, I came to a barrier and a general driving ban and no more mtb route 673 sign. Instead of ignoring this barrier and continuing on the road (as I later learned from others), I rode back onto the tarred road to Poschiavo and missed an interesting and challenging part of this route. But even with what I did, the route was super beautiful; I have part of it on video and share this on the youtube link: https://youtu.be/Pb-j2hBAbw8

The video is all from the rider's point of view (helmet camera with stabilizer) without seeing the rider or parts of his bike. The video is therefore also suitable for watching the tour during home fitness (training on the treadmill or bike) on a monitor or large screen and it is then as if you were doing the tour yourself. (virtual reality)

We rode the route at the beginning of September 2019.
We really enjoyed the scenery and the riding.
The detour to Lagh da Palü is not recommended from our point of view, because from the lake to Cavaglia the path is very rough and only partially rideable. We would follow the official route 637 here another time.

A very scenic tour. The section directly after the small reservoir is quite challenging - some riders will have to push here. The remaining meters in altitude are all the more flowy and you are quickly down in the valley.